Sulfuric Acid 50% v/v

Hazard statements (CLP)

H220, H290, H302, H314, H315, H318, H335

Code

Statements

H220

Extremely flammable gas

EU Classification

Directive 67/548/EEC or 1999/45/EC Harmful (Xn; R22) Irritant (Xi; R38-41)

CLP CLASSIFICATION

Corrosive to metals - Category 1 - Warning (Met. Corr. 1; H290) Acute toxicity, oral - Category 4 - Warning (Acute Tox. 4, oral; H302) Skin irritation - Category 2 - Warning (Skin Irrit. 2; H315) Serious eye damage - Category 1 - Danger (Eye Dam. 1; H318)

2.2 Label elements

Label in accordance with Regulation (EC) No 1272/2008 * • Dangerous ingredient(s) : Ferric chloride Areas in which safety distances are to be observed are, if applicable, also the entrances to the gas storages, to be labelled according to VSG 1.5. 2.4.6 Mechanical hazards Gas storage and its equipment parts must be protected from mechanical dam- age. For protecting the gas storage and its equipment parts from impact from vehicles in hazardous areas, the gas storage and its equipment parts must be protected, e.g., by bumpers, by areas not accessible to vehicles, by enclosing or complying with the safety distance. German Agricultural Occupational Health and Safety Agency 25 2. Parts of the System Freestanding gas storage, for example, pillow type storage containers and membrane domes from flexible material, must be protected against mechanical damage. This requirement is to be met using a protective fence that is to be erected around the gas storage. For a protective fence distance of less than 850 mm, the fence must be secure against penetration. The protective fence must be designed as a fence that permits no access, e.g., from wire netting with a height of at least 1.5 m. 2.5 System control and process control engineering In principle, the safe operation of a system must be guaranteed. In particular, an overfilling of the digester, an unintended flow of substrate into the pipe and container lines of the system, an impermissible pressure increase in the digester, as well as an uncontrolled escape of gas, must be prevented. Control systems with safety functions must be fail-safe if they are not secured by a redundant system, e.g., a mechanical overpressure protection against over- pressure, or e.g., an overflow spillway. In the case of a failure of the auxiliary energy source (power, hydraulic or pneumatic supply of the biogas system), the safety shutdown, the activation of the emergency shut-off switch, the system, or the relevant system parts must en- ter into a safe state. The safe state can be reached using control technology, hydraulic, or mechanical measures. Examples • Closing the automatic gas rapid shutoff device at the CHP unit. • Switching off the corresponding gas compressor. • Switching off all parts that are not EX-protected in gas-pressurized machine rooms (CHP unit, gas cleaning, etc.). • Enough clearance space so that, in the case of a failure of the agitator, no impermissible build-up of substrate occurs in the digester, and as a result, the cover is lifted off. • Closing the feeder so that no backflow of the substrate occurs into the feed system (e.g., mixing tank, stall). • External possibilities for supplying feed must be able to be blocked in the case of a system failure so that the possibility of overfilling is excluded. • The lowering of the fill level must not lead to an uncontrolled release of gas, e.g., from the feed technology. German Agricultural Occupational Health and Safety Agency 26 2. Parts of the System In the design of the safety-related control parts, the currently effective standards for electrical equipment of machines and safety-related parts of con- trols must be consulted. A hazard and risk analysis must occur according to the standards. 2.6 Gas processing 2.6.1 Desulphurization with iron-containing compounds or activated carbon If biogas is desulphurized by means of iron-containing compounds, or by activated carbon, there exists a danger of self-heating during the regeneration. The safety information from the manufacturer, in particular, information about the exchange of biogas treatment media, must be followed. 2.6.2 Desulphufirzation by air injection in the gas room over the digester The air-dosing pump must be adjusted so that it delivers at most a volume flow of 6 per cent of the biogas generated in the same time period. The air dosing must be dimensioned so that so that even in the case of a failure of the air flow, no significantly higher quantity of air can be supplied. In the supply to the gas room, a non-return protection (non-return valve) is required, as close to the gas room as possible. Between the non-return protection and the gas room, no ad- ditional devices can be inserted except for a blocking device. 2.7 Gas Lines 2.7.1 Design and material Gas-carrying lines must be designed according to the generally recognized rules of the technology. The correct production and impermeability must be proven, e.g., by manufacturer’s certification (see sample, Appendix 2). Pipelines must be resistant to its contents and to corrosion. Pipes that are resistant to biogas are composed of, for example, steel, stainless steel, polyeth- ylene (PE-HD) and PVC-U. Tip – PVC-U pipes: PVC is not UV-resistant and has a low resistance to impact. For PVC use, correct storage and processing must be observed. For this, particular attention must be paid to the information regarding installation and usage, e.g., the manufacturer’s information, as well as the bonding information German Agricultural Occupational Health and Safety Agency 27 2. Parts of the System and the installation information from the Plastic Pipe Association. The expertise of the pipe installer must be verified. Copper is not resistant to biogas; brass and red brass have proven to be suitable (customary PVC-KG-pipes are not permissible, because they correspond only to a structural stability of maximum 0.5 bar). Pipelines including all equipment parts and flexible connectors must have the structural stability of at least 1 bar. 2.7.2 General Information In general, steel pipes should be used for the pipelines. Plastic pipelines can be used, in general, outside of closed rooms with installation under the ground and above ground as a connection line of the membrane storage and as a connection line of the digester. Plastic pipelines must be protected from mechanical and thermal damage. Spigot and socket joint connections that are not longitudinally force-locked must be secured according to the typical pressures so they cannot be pushed. The pipeline connections must be longitudinally force-locked. Tip If gas lines are installed outside of the biogas system or on surfaces that are not in spatial functional connection to the biogas system, plastic gas lines must be laid according to the technical specifications of DVGW [German Technical and Scientific Association for Gas and Water] G 472 Rules. 2.7.3 Protection against mechanical damage Mechanical damage due to settling (e.g., at passages through walls) must be avoided by appropriate passages and corresponding connections. 2.7.4 Frost safety In the case of moist gas, the pipelines must be laid so that they are frost-proof. Condensate collectors must be constructed frost-proof and continuously capable of function. German Agricultural Occupational Health and Safety Agency 28 2. Parts of the System 2.7.5 Connection lines Connection lines to the gas storage within the installation room of the gas store are components of the gas storage. 2.7.6 Labelling Pipelines must be labelled according to DIN 2403 according to the flow substance and the direction of flow. Color for the labelling: yellow. The location of underground gas pipelines must be marked with gas pipeline warning tape. 2.7.7 Gas-carrying connection parts belonging to the CHP unit The suitability of the gas-carrying, flexible connection pieces belonging to the CHP unit and the equipment components of the charge-air cooling must be certified by the manufacturer of the CHP unit. 2.8 Instruments, Safety Equipment, and Gas-carrying System Parts 2.8.1 General information Instruments, safety equipment, and gas-carrying system parts must be installed so that they are frost-free, according to the generally recognized rules of the technology, and checked for tightness. For the tightness check, the instruments, safety equipment, and gas-carrying system parts must correspond to the requirements of TRBS 2152, Part 2, Section 2.4.3. In addition, they must be sufficiently resistant to its contents, corrosion, and pres- sure. With respect to suitable materials, Section 2.7 applies. 2.8.2 Approval Instruments and gas-carrying system parts for which there is no DVGW approval must be designed to a pressure resistance that corresponds to the ten-fold positive operating pressure and must be resistant to biogas, e.g., sight glass, cover for access opening. German Agricultural Occupational Health and Safety Agency 29 2. Parts of the System 2.8.3 Operation It must be possible to operate instruments from a secure platform. Fixtures for gas removal must be secured against unauthorized and unintentional opening, e.g., by securing the handles. 2.8.4 Accessibility and sealing liquid Condensate separator and safety equipment must be accessible at all times. Permanently attached steps are not permissible unless the condensate separator has forced ventilation (see also, BGR 117, GUV R 126). Pressurization facilities with sealing liquid in overpressure and under-pressure pro- tectors, as well as condensate and dirt separators, must be easy to monitor and maintain without hazard, and should be accessible without having to enter into the shafts or pits. Pressurization facilities with sealing liquid must be designed so that, during the triggering, the sealing liquid cannot escape but flows back again on its own. In order to prevent gas from escaping, with sealing liquid facilities that serve as condensate separators and not as overpressure/under-pressure protectors, the fluid facilities must correspond to at least five-fold of the triggering pressure of the overpressure protection. 2.8.5 Flashback safe equipment Flashback arrestors must be installed in front of gas-consuming equipment, such as boilers and CHP units, as close to the equipment as possible, corresponding to the instructions of the manufacturer. 2.8.6 Arrangement and implementation Take note of the example for the gas diagram (1.2). Note the arrangement of the overpressure and under-pressure protectors. 2.8.6.1 Safety equipment, overpressure/under-pressure protection Every gas tight container must be equipped with at least one safety device against exceeding or falling below acceptable pressure. This does not apply to containers that serve only for the storage of gas. If required, the gas that is German Agricultural Occupational Health and Safety Agency 30 2. Parts of the System discharged must be led off without hazard. Through a separate under-pressure monitor in the gas system or an equivalent protective measure, the under- pressure protector must activate a forced shutdown of the gas-consuming equipment and an error message must occur. It must be possible to shut off the gas containers individually and to shut them off from each other. The overpressure and under-pressure protectors within the system must be designed, arranged, and monitored, and the overall biogas system must be op- erated so that all operating states in the digester are controlled. Foam formation represents a disruption of the operation, and it must be prevented by operational measures. Destruction due to the formation of foam must be prevented, e.g., by burst protection, pressure release protection, or sufficient storage space. The suitability of the overpressure/under-pressure protector must be proven by a documented evaluation and functional description. If they are implemented in a submerged state, they must not run empty, dry, or freeze. It must be pointed out in the operating instructions that the safety equipment must always be checked after an operational malfunction and, during normal operation, at least once a week. For this, the specifications of the manufacturer must be observed. Tip Safety equipment can become ineffective due to stiffness as a result of con- tamination, corrosion, stoppages, or freezing. A modification of the interior pressure can be caused by: • gas production without discharging gas, • in the case of supplying or removing gas or substrate by pumping. Liquid seals as safety equipment must be designed so that the sealing liquid can flow back again on its own in the case of an overpressure or under-pressure situation. There must be no means for blocking or shutting off the supply lines to the overpressure and under-pressure protection. Overpressure and under- pressure protection must be designed to be frost-safe. Usually, access to over- pressure and under-pressure protection must be designed and accessible with stairs , because due to the frequent use, there is an increased risk of accidents. German Agricultural Occupational Health and Safety Agency 31 2. Parts of the System 2.8.6.2 Discharge lines of the overpressure/under-pressure protection The exhaust lines of the overpressure and under-pressure protection must discharge at least 3 m above the ground, and • discharge 1 m above the roof or the upper edge of the container, or • must be displaced at least 5 m away from buildings and passageways. The 1-meter area around the discharge opening of the exhaust lines is a Zone 1 area. Refer to the pollution control regulations. The exhaust gas of the gas flame must be discharged above the roof, or via the exhaust line, which must be at least 5 m from buildings and passageways, and whose discharge must be at least 3 m above the ground (see also, Section 2.4.5.3). German Agricultural Occupational Health and Safety Agency 32 3. Installation Rooms 3.1 Gas firing systems The technical regulation for gas installations apply to the installation rooms for boilers (see Appendix 11). Refer to the regional ordinances for combustion equipment units. 3.2 Combined heating and power unit (CHP) 3.2.1 Installation in neighbouring buildings without common break rooms 3.2.1.1 Accessibility Installation rooms must be designed and dimensioned so that the combined heat and power units can be properly installed, operated, and maintained. This is generally achieved if the combined heat and power unit is accessible from three sides. Doors must open in the escape direction. 3.2.1.2 Floor drains Floor drains must have oil separators. Alternatively, a catch basin, which can hold the entire quantity of motor oil, must be provided underneath the motor. 3.2.1.3 Ventilation Installation rooms must have supply air and exhaust air openings that cannot be closed. These allow a cross ventilation of the installation room. With technical ventilation, it must be guaranteed that the exhaust is led away from the ceiling area. In the case of natural ventilation, the supply air opening must be located in the area of the floor, and the exhaust air opening must be located on the opposite wall in the area of the ceiling. The exhaust of the CHP installation room must be discharged directly into the open air. Tip The open minimum cross section “A” for the supply air opening/exhaust air opening is given by the following formula, where A = 10 P + 175 A = free cross section, cm² P = maximum specified electrical power from the generator, kW Example: 22 kW el = 395 cm² 30 kW el = 475 cm² German Agricultural Occupational Health and Safety Agency 33 3. Installation Rooms 3.2.1.4 Cutoff It must be possible to shut off the combined heat and power unit at any time by using an illuminated switch located outside of the installation room. The switch must be labeled permanently and be easily visible with “Emergency Shut-off Switch for Combined Heat and Power Unit ” and must be accessible. 3.2.1.5 Cutoff for the gas supply It must be possible to shut off the gas supply to the combined heating and power unit, in the open, outside of the installation room, as close to the CHP unit room as possible. The on and off position must be labeled. The same require- ments apply also to electrically-operated shutoff valves. 3.2.1.6 Use of turbo chargers With the use of motors, in which the gas-air mixture is compressed by the turbo charger, the following precautions are necessary for preventing or limiting po- tentially explosive atmosphere in the event of damage: a. room air monitoring of the installation room with gas-warning device (GWE) that, according to RL 9L 95/9/EU, corresponds to at least Category 3 in its ignition protection and its measurement technology function, and an automatic switch-off of the aggregate and the electrical system, or b. room air monitoring of the installation room with a gas-warning device (in the case of an installation in the EX area complying with RL 94/9/EU with respect to ignition protection of the necessary category), which, if neces- sary, was also checked for functionability according to RL 94/9/EU, how- ever, at least with a gas-warning device checked for functionability by a national test center, and automatic switch-off of the aggregate and simul- taneous switching on of a forced ventilation system that is dimensioned analogously to point c), so that no potentially explosive mixture can form, or c. forced air ventilation of the aggregate room with a minimum air ex- change, which effects a sufficient dilution of the maximum possible gas quantity. The required minimum air exchange amounts to 35 m³/h of air per 1 kW of installed electrical power. Then, the maximum gas concentra- tion amounts to a maximum of approximately 1.5% vol., and therefore cor- responds to approximately 25 per cent of the lower gas explosion limit (methane 4.4–16.5% vol.). German Agricultural Occupational Health and Safety Agency 34 3. Installation Rooms In the case of opened shutoff valves, the fans must run, and their function must be monitored by a flow monitor. 3.2.1.7 Compressors in the installation rooms The installation room is not a potentially explosive area if the gas-carrying system parts, e.g., gas supplying equipment and CHP unit within the installation room, are constructed to be continuously gas tight during operation. In addition, the use of gas-warning devices (GWE) can be helpful. If the tightness of the gas-carrying system parts, e.g., gas supplying devices and CHP unit within the installation room, in ongoing operation is not continuously guaranteed, protective measures must be implemented. If the following protective measures are deployed, no potentially hazardous zone exists in the installation room: 1. A minimum air exchange is continuously guaranteed by means of a ventilator and an airflow monitor. The air exchange dilutes the maximum possible air quantity to a maximum gas concentration of 20 per cent LEL (lower explosion limit) in the installation room. Example Ventilation: Vmax CH4 leakage rate ______________________ < 20% of the LEL CH4 in air Vbiogas + V air of ventilation Note The leakage rate in this formula is the leakage rate of the compressor. Depending on the operating pressure and the specified leakage rate, if applicable, a zone must be indicated in proximity to the gas escape site if a potentially hazardous quantity can escape. The secure discharge of the air from the installation room must be guaranteed. or German Agricultural Occupational Health and Safety Agency 35 3. Installation Rooms 2. The installation room must be provided with a gas-warning device (GWE). The possible gas escape of a CH4/CO2 mixtures into the machine room is monitored and locked by a safety room air monitor with the following safety oriented functions, e.g., 20% of the LEL (0.9% vol. CH4 ) in the room air with the following actions: • visible and audible warning and • supply air or exhaust air to 100% performance e.g., 40% of the LEL (1.8% vol. CH4) in the room air with the following actions: • visible and audible warning • supply air or exhaust air to 100% performance • automatic switch-off of the gas utilization and closing of the gas supply outside of the installation room or shut down (e.g., energy supply) of all resources in the machine room that are not EX-protected Information for sufficient dimensioning of the ventilation or exhaust: Vmax CH4 with maximum gas supply of the gas compressor the BGA [German Health Authority] (2-F-Case) _______________________________________________ < 50% of the LEL CH4 in air V Biogas + Vair of ventilation and exhaust The gas-warning device must conform at least to the Directive 94/9/EU according to Category 3G. This applies also for the ignition protection of the sensing devices installed in the installation room, as well as for the measurement technology function. The gas-warning device continues to be operated in the case of exceeding the second alarm threshold, i.e., it is not switched off. The maintenance of the gas-warning device must occur according to the manufacturer’s instructions. For ventilation, the secure discharge of the air from the installation room must be guaranteed. The air must be discharged from the installation room into the open air. Try to achieve cross ventilation. Sometimes, forced ventilation is also necessary (see the manufacturer’s instructions). German Agricultural Occupational Health and Safety Agency 36 3. Installation Rooms Along with the gas-warning device, the suction-operating fans of the ventilator must correspond to the device category 3G. If a CHP unit (or several) and the emergency flare are operated via a compressor, the ventilation in the installation room of the compressor must continue to be operated for as long as the compressor functions. 3.2.1.8 Shutoff valves Two shutoff valves must be installed in the gas line in front of each motor aggregate. The valves must automatically close when the motor stops. The gas tightness of the intermediate space must be checked regularly. If the supply line to the motor is operated constantly with a primary pressure > 5 mbar, even when the motor is stopped, an automatic monitoring of the intermediate space is required. 3.2.1.9 Rooms into which gas can penetrate Rooms into which the gas can penetrate and rooms that must be regularly accessible for the operation of the system must be ventilated so that no hazardous gas mixture can form. It should be possible to leave these rooms without entering the CHP unit room. If the rooms cannot be appropriately ventilated, EX-protective measures must be implemented corresponding at least to the requirements of Zone 2. In addition, the occupational exposure limits (OELs) must be maintained continuously and safely. 3.2.2 Installation in building not belonging to the system 3.2.2.1 General information The specifications of Section 3.2.1.1 to 3.2.1.9 apply accordingly. 3.2.2.2 Implementation Walls and supports, as well as ceilings above and below the installation room, must be fire resistant F90A DIN 4102, or correspond to the appropriate requirements of DIN EN 13501, and must be composed of noncombustible construction materials. Coverings and insulating layers composed of combustible construction materials must not be used for walls, covers, and supports. German Agricultural Occupational Health and Safety Agency 37 3. Installation Rooms 3.2.2.3 Doors Doors in the fire resistant walls must be at least fire retardant, T 30 DIN 4102, and must be self-locking; this does not apply to doors that lead to the outdoors. 3.2.2.4 Openings Ventilation lines and other lines can be led through walls and ceilings only if the lines themselves cannot spread fire or if measures have been taken against the spread of fire (e.g., cable shielding with general construction supervision approval, fire prevention dampers). Intermediate spaces in the openings must be filled with noncombustible and stable material. 3.3 Installation of gas-warning devices Sensing devices should be placed above, depending on the gas properties, in the proximity of possible release sources. The influences of the ventilation and its possibly different operating states must be considered in the placement. Evaluation units should be installed outside of the room to be monitored. The installation should be in an adjacent room into which the gas mixture cannot penetrate from the area being monitored and into which also no hazardous gases can be released. It must be verifiably guaranteed that no hazardous gas concentrations can occur due to the gas analysis. Otherwise, a forced ventilation with a minimum air exchange must be installed, which effects a sufficient dilution of the maximum possible gas quantities, or the gas analysis must be implemented in the CHP unit. Operating instructions must be written for the case of the alarm being triggered by the gas-warning device or interruptions of the gas-warning device. German Agricultural Occupational Health and Safety Agency 38 4. Operation Operating instructions must be available for taking the system into service (see sample in Appendix 1). The system is taken into service by the respective technical specialist (see Acceptance Log Appendix 2). The operation and maintenance of the biogas system must be performed only by reliable persons familiar with the work. At least two persons at the biogas system must have received certified operator training. The operating instructions with safety information must be observed (see Appendix 3). Operating instructions must always be placed permanently in the operating room. An operational log (see Appendix 4) must be kept in which all daily measurements, control, and maintenance work, as well as malfunctions, is recorded. In the case of malfunctions at the gas-consuming devices, the gas production of the system must be reduced through suitable measures in order to keep the exhaust quantity as low a possible. Suitable measures for reducing the gas production are, e.g.: • stop the supply of substrate • stop the supply of heat to the digester In the case of malfunctions and for taking the biogas system out of operation, perform the measures listed in Appendix 5 and 6. German Agricultural Occupational Health and Safety Agency 39 Appendix 1 Operating Instructions for Initial Startup/Restart of a Biogas System Sample The initial startup of a biogas system is a special operating state, which requires special actions. The EX-zones, specified in the Explosion Protection Document, consider the operating state based on various conditions. Therefore, these par- ticular hazards are considered separately in the operating instructions. 1. During the initial startup, a hazardous, potentially explosive atmosphere can occur in the gas space of the digester container. Ignition sources (see, for example, Section 1.4.4) must be avoided (e.g., operate the agitator submerged). 2. The empty digesters are initially blocked from the gas collection system. 3. The digesters are connected to the atmosphere via the operationally ready overpressure protector and the exhaust lines. 4. The digesters are filled within a short time period with substrate that is as active as possible, until all inlets and outlets (liquid valve closure disks) are sealed with substrate. 5. The fermentation substrate is heated. 6. During the startup/heating of the system, the system must not be fed further. 7. The gas generated during the starting of the digestion process discharges via the exhaust line (gas overpressure protection) into the open air, and displaces the air that is present in the digester. 8. After testing the gas quality, biogas fills into the gas system and the gas storage. The gas quality is sufficient and there is not explosion hazard if the methane content of the gas is greater than 30% and the oxygen content is < 3%. 9. The CHP units are turned on. They automatically suction the gas from the gas storage. Sufficient biogas quality can be determined by gas measurement. 10. All safety equipment must be checked for the proper function. German Agricultural Occupational Health and Safety Agency 40 Appendix 2 Inspection Document for Biogas Membrane Storage, see also Appendix 13 Sample Address of the site: Biogas system: Operator of the system: System installer: Inspector of the membrane storage: Membrane Storage Manufacturer: Company: Material: Dimensions: Gas impermeability: For methane: cm3/m2, d, bar Strength: Tear strength N/5 cm Tensile strength N/5 cm Temperature Resistance Seals: Installation procedure: Leak Test Test area: Test method: Test medium: Test result: Sample Inspection Document for Gas-Carrying Pipes Address of the site: Biogas system: Operator of the system: System installer: Inspector of the piping: German Agricultural Occupational Health and Safety Agency 41 Appendix 2 Piping in the CHP unit room in the ground Manufacturer: Material: Dimensions: Strength: Pipe connections: Seals: Leak Test Test section from – to Test method: According to the technical rules for gas installation DVGW-TRGI 2008 G469 and G600 Test pressure Initial test with 1 bar, main test with 110 mbar Test duration Initial test 10 min, main test 10 min. Test medium: Air Test result: Note: Location/Date: Stamp/Signature: German Agricultural Occupational Health and Safety Agency 42 Appendix 3 Operating Instruction for a Biogas System in Normal Operation (see Section 1.5) Sample Independent of this sample operating instruction, the operating instructions of the manufacturer of all individual components must be observed, such as the CHP unit, pumps, mixer, membrane storage, under-pressure monitor, room air monitor, etc.. In general: • During filling and emptying, pay attention to pressure fluctuations and ensure good accessibility to the operating equipment. • Avoid ignition sources, according to 1.4.4, in the zones according to the Explosion Protection Document (see also, Appendix 9). Daily: • Record the gas meter reading and operating hours of the motor. • Check the motor oil level. • In the control room, at the control box, check whether the malfunction lights are illuminated. • Check the water pressure in the heating system. • Check the air-dosing pump of the desulphurization system for operability. • Monitor the digester temperature. • Select the agitation intervals so that no layer of scum/sediment layer develops. • For all inlets and outlets, assure that the liquid manure/substrate flow is maintained according to the process regulations. • The airflow injected for desulphurization must be matched to the current gas production rate (max. 6% vol.). • Check the fill levels in the digester and end storage. • Check the membrane connectors (e.g., attachment hose at the membrane gas storage). Weekly: • Check the fill level of the sealing liquids in the overpressure and under-pressure protectors and condensate separator; if necessary, in the case of a danger of frost, check the antifreeze agent (if the weather warrants, daily checks are also required). • Check the submerged propeller function; observe whether vibrations are present. • Visually inspect the motor and the lines. German Agricultural Occupational Health and Safety Agency 43 Appendix 3 Weekly: • Check the gas magnet valve for function and contamination. • Check the intermediate space of the self-closing gas shutoff valve for tightness. Monthly: • Actuate all scrapers a few times so that they are not stuck. • Possibly remove the oil deposits in the CHP unit and clean the oil catch basin. Twice a year: • Check the ventilation and exhaust in the machine room of the CHP unit. • Inspect the electrical systems for damage. • Check the under-pressure monitor of the gas system for function. • Check the function of the gas sensors, fire detector (if present). Annually: • Check the gas-carrying system parts for damage, tightness, and corrosion. • Calibrate the gas sensor with suitable test gas. Every 2 years: • Check the fire extinguishers. In the zones, according to Section 1.4.4.2, ignition sources must be avoided, e.g.: • smoke, fire • non EX-protected electrical operating resources Pits and shafts: Before entry and during presence in the pits and ducts, it must be guaranteed that there is no hazard of poisoning, as well that there is sufficient breathable air present. Operating equipment must be reliably secured so they don’t switch on (lock out procedures). Ensure that there is sufficient ventilation. In the case of insufficient ventilation, there is a danger of asphyxiation, fire, and explosion. German Agricultural Occupational Health and Safety Agency 44 Appendix 4 Operations Log (example) Sample Date: Gas Gas Con- Operating Electricity Digester Substrate Maintenance Unusual Meter sumption Hours [h] Meter Temperature Supply Work Incidents Reading [m³/day] [kWh] [°C] [m³] German Agricultural Occupational Health and Safety Agency 45 Appendix 5 Operating instructions for a biogas system in the case of malfunction Sample Independent of this sample operating instruction, the operating instructions of the manufacturer of all individual components must be observed. Gas storage room • shut off gas supply • empty the gas storage • avoid ignition sources (see Section 1.4.4) • entry for authorized personnel only after and with sufficient ventilation, while being accompanied by a second person (who remains in the vicinity of the opening to the storage) and being secured, e.g., with a rescue apparatus and lifebelt (harness) Heating, hot running machines and parts, substrate or oil becoming hot • avoid contact with hot surfaces, fluids, gases, ... • caution with hot water discharge: potential scalding hazard! Machine room and combined heat and power unit • shut off gas supply outside of the machine room • activate the emergency off switch outside of the machine room • if necessary, force ventilation (e.g., in the case of gas odor) • if there is a gas odor, avoid ignition sources, e.g., non EX-protected light sources, open flame, or formation of sparks. Danger of explosion! • if the gas alarm comes from a gas-warning device, separate operating instructions must be created and followed Electrical system • work on the electrical systems must be performed only by a skilled electrician Liquid manure lines and scraper • Get rid of blockages immediately • in the case of malfunctions in the pump system: shut off all scrapers after the pumps are stopped Pumps and mixer • switch off the electrical supply, and secure the switch against unintentional actuation German Agricultural Occupational Health and Safety Agency 46 Appendix 5 Pits and shafts • After malfunctions, all safety equipment must be checked for the proper function. Note Before entry and while in the pits and ducts, it must be guaranteed that there is no hazard of poisoning, as well as that sufficient breathable air is present. Operating equipment must be reliably secured against switching on. Ensure that there is sufficient ventilation. In the case of insufficient ventilation, there is a danger of asphyxiation, fire, and explosion (see also, Appendix 7). German Agricultural Occupational Health and Safety Agency 47 Appendix 6 Operating Instructions for Shutting Down a Biogas System Sample The shutdown of a biogas system is a special operating state that requires special actions. The EX-zones, specified in the Explosion Protection Document, consider the operating state based on various conditions. Therefore, these par- ticular hazards are considered separately in the operating instructions. 1. Stop the substrate supply into the digester container; the substrate removal from the container continues to occur. The quantity of the substrate removed must not be greater than the quantity of generated gas in the digester in order to prevent a potentially hazardous atmosphere. 2. If the quantity of substrate removed can become greater than the quantity of gas generated, the digester container is locked against the gas capturing system, and the connection to the atmosphere is created, e.g., by emptying the sealing liquid supply. By adding air, a potentially explosive atmosphere can develop in the digester. Ignition sources according to 1.4.4 must be avoided. 3. The digester container must be blocked from the gas capturing system in order to avoid a backflow of gas. 4. A potentially explosive atmosphere can form around outlet openings. Ignition sources, e.g., according to 1.4.4, must be avoided. 5. Before entry into and while in the digester container, it must be guaranteed that the danger of asphyxiation, fire, and explosion has been safely prevented by sufficient ventilation and that sufficient breathable air is present. Operating equipment (e.g., pumps and agitators) must be secured against being switched on (lockout procedures). German Agricultural Occupational Health and Safety Agency 48 Appendix 7 Operation Information Workplace/Work area : Biogas system, liquid manure pits, liquid manure ducts, liquid manure storage facilities, shafts, etc. Activity: Stirring, flushing, pumping, transferring, removing liquid manure or sub- strate, repair and maintenance work, and presence in the liquid manure or sub- strate work areas Identification of Hazardous Substances Liquid Manure and Biogases (Hydrogen sulphide, Methane, Carbon Dioxide, Ammonia) Hazards for Humans and the Environment The gases are released especially through the movement of the liquid manure or substrate. In the process, hazardous gas concentrations can develop, which remain over long periods. • life threatening danger – hydrogen sulphide (H2S) Caution: H2S disables the sense of smell, higher concentrations are no longer noticed • danger of asphyxiation due to carbon dioxide (CO2) • explosion hazard due to methane (CH4) • health hazard due to ammonia (NH3) Protective Measures and Rules of Conduct Never enter into the digester, storage facilities, pits, shafts, etc., without protective equipment. Enter only with a breathing apparatus that is not dependent on the surrounding air, e.g., fresh air suction hose device and lifebelt, as well as approved rescue apparatus. When working with liquid manure or substrate, any kind of ignition source must be avoided: • switch-off gas jet devices • smoking is prohibited • no light test German Agricultural Occupational Health and Safety Agency 49 Appendix 7 • do not perform any welding or thermal cutting – sparks and welding beads can fall also in pits that are far away (If such work is absolutely necessary, ensure good ventilation, e.g., using fans. Pits must be covered.) Conduct in Dangerous Situations Enter into pits, etc., for rescuing casualties only with a breathing apparatus that is not dependent on the surrounding air, Lifebelt, and rescue apparatus. Provide sufficient fresh air. Contact the fire department! Conduct in Case of an Accident – First Aid After breathing liquid manure gas or biogas, provide fresh air. Unconscious person: Establish breathing and place victim on their side. Contact the physician immediately! Provide information about poisoning due to hydrogen sulphide. First Responder: Physician: Emergency: Date: Employer’s signature: German Agricultural Occupational Health and Safety Agency 50 Appendix 8 Proposal for the Contents of an Alarm and Hazard Defence Plan Sample A biogas system is a structural system that, for the appropriate assessment of the fire hazard, requires an in-depth examination during the planning and a close coordination of the tactical operational necessities with the leaders of the emergency response forces or the local fire authorities. As a rule, it is necessary to develop a common plan for the tactical deployment of the fire department in the event of a fire or other technical assistance (fire protection plan). The fire protection plan is drawn up by the system operator and then must be coordinated with the responsible fire department to their tactical requirements. In its final form, the fire protection plan must be presented to the responsible regulatory agency, at the latest one week before taking the system into operation. Depending on the circumstances of the individual case, the fire protection plan as a rule must contain information and diagrams for the following points: 1. Access roads and passageways, as well as the deployment areas and movement areas for the fire department. 2. Verification of the necessary water quantity for fire fighting and the verification of the supply of water for fire fighting. 3. Dimensions, position, and arrangement of the reservoir of water for fire fighting. 4. The system of the outer and inner fire retardant locks in the fire compartments or fire fighting sections, as well as the system of smoke compartments with information about the position and arrangement of the components. 5. Position, arrangement, dimensions, and designation of the escape routes on the site and in the buildings with information about emergency lighting. 6. Information about the users of the system. German Agricultural Occupational Health and Safety Agency 51 Appendix 8 7. Position and arrangement of technical systems for the building, especially the cable and duct systems, if necessary, with information concerning fire behaviour in the area of the escape routes. 8. Position and arrangement of possible ventilation systems with information about the fire protection construction. 9. Position, arrangement, and dimension of the smoke and heat exhaust systems. 10. Position, arrangement, and if applicable, dimensions of systems, equipment, and devices for fighting fires (e.g., fire extinguishing devices) with information for protected areas and for the stockpiling of special extinguishing agents. German Agricultural Occupational Health and Safety Agency 52 Appendix 9 Examples Zone Classification System Part Type of Zone 1 Zone 2 Impermeability General Around: Equipment and 1 m around the outlet 2 m around Zone 1 System parts, equipment system parts with point parts, connections operational gas outlet tight – 3 m around system part permanently tight – Examples Burst safety device that in – 3 m around system normal operation seals part securely Outlet opening of exhaust 1 m around outlet 2 m around Zone 1 lines opening Service Opening If the service openings are With operational gas 1 m around the outlet 2 m around Zone 1 not opened during normal outlet point operation tight – 3 m around system part permanently tight – Gas Storage Around: 3 m from above Simple membrane storage out in the open Simple membrane domes on digester containers 3 m to the side and storage Around ventilation and exhaust openings of 2 m downward at 45° vapour-sealed gas gradient storage rooms Double membrane domes with digester containers – and storage, if the through-flow leads the diffusing biogas sufficiently diluted (<< 10% LEL) from the gas storage, and the exiting air is continuously monitored. German Agricultural Occupational Health and Safety Agency 53 Appendix 9 System Part Type of Zone 1 Zone 2 Impermeability Condensate Separator Room that contain the con- densate collector. With open water locks, forma- tion of a hazardous, possibly explosive atmosphere must be anticipated as a result of puncture or drying out of the water locks, or as a result of faulty operation: a) with the discharge in closed rooms without ventilation – Zone 0 in the entire room b) with the discharge in closed Entire room 1 m around rooms with natural ventilation openings of the enclosed room c) closed drainage system, – locks with double locking de- vices or automatic drainage For the total space, 1 m around openings of the en- closed room. Solid Substance Dosing If during normal operation, – forced submersed supply is guaranteed. Dimensioning of the Area of Zone 1 A spherical area with a radius of 1 m around is considered an area of Zone 1 (see also, TRBS 2152) such as system parts, equipment parts, connections, sight glasses, pass-through, service openings at the gas storage and at the gas-carrying part of the digester container and around the outlet openings of exhaust lines, if an operational outlet of biogas must be anticipated. The radius of 1 m applies in the case of natural ventilation. Under normal operating conditions, releases into closed rooms must be avoided. If possible, the entire room is Zone 1. German Agricultural Occupational Health and Safety Agency 54 Appendix 9 Dimensioning of the Areas of Zone 2 Gas-Carrying System Parts A spherical area with a radius of 3 m around system parts classified as impermeable are considered areas of Zone 2 such as equipment parts, connections, pass-through, service openings, as well as burst plates. The radius of 3 m applies in the case of natural ventilation. Closed rooms are entirely areas of Zone 2 (see also, TRBS 2152). A spherical shell with a radius of 2 m thickness around system parts not classified as impermeable are considered areas of Zone 2, such as equipment parts, connections, sight glasses, pass-through, service openings, and at the gas-carrying part of the digester container, as well as around the outlet openings of exhaust lines, if these have an operational outlet of biogas. Gas Storage If the membrane storage is stored out in the open or housed in a room ventilated all around, the area of Zone 2 encompasses the periphery of 3 m upwards and to the side, and 2 m downwards with a 45° gradient. In the case of housing the membrane storage in a vapor-tight and, therefore, extensively gas-tight room, Zone 2 encompasses the interior of the gas storage room and the periphery of 3 m around the ventilation and exhaust opening upwards and to the sides; the extent downwards amounts to 2 m with a 45° gradient. Vapour-tight rooms can be rooms constructed with, e.g.: • brickwork walls with trim • concrete walls • walls whose coating consists of non-combustible and spackled plates • standardized containers with metal walls Note Around system parts that are permanently impermeable, according to TRBS 2151, Section I 1.3.2.2 (see Appendix 10), there is no zone German Agricultural Occupational Health and Safety Agency 55 Appendix 9 Double Membrane (Support Air) No zone is present around the outer membrane and in the intermediate space between the two membranes if the through flow sufficiently thins (< 10% LEL) the biogas diffusing from the gas storage and leads it off in a targeted manner, and the air that is being discharged is continuously monitored according to the maintenance plan (manufacturer specification). A ring-shaped potentially explosive atmosphere can occur around the transition to the digester if the connection is not implemented in a permanently imper- meable manner. If it is not possible to prevent backflows into the support air blower, these are to be implemented according to 94/9/EU. Example – Biogas System, Top View with Permanently Tight System Parts German Agricultural Occupational Health and Safety Agency 56 Appendix 9 Example – Housed Gas Storage (Storage Room Without Further Technical Measures) German Agricultural Occupational Health and Safety Agency 57 Appendix 10 Tightness of System Parts (see TRBS 2152, Part 2, Section 2.4.3) 1. General Information The formation of a hazardous, potentially explosive atmosphere outside of system parts can be prevented or limited by the impermeability, or tightness, of the system parts. For this, distinction is made between: • tight system parts, • permanently tight system parts, and • system parts with operational outlet of combustible substances. Tip 1 With the construction of system parts for handling combustible gases, liquids, and dusts, the material should be selected so that it can withstand the anticipated mechanical, thermal, and chemical operational demands. Hazards due to reactions of the wall materials with the combustible mixture must be excluded. Tip 2 For the material selection, the corrosion behaviour must be considered. With laminar wear, the calculation of the wall thickness must consider extra thickness; against pitting corrosion, suitable materials must be selected as principal protective measures; in addition and in particular, appropriate preservative measures must be performed during the idle state. 1.1 Permanently Tight System Parts 1. With system parts, which are permanently tight, no releases are to be expected. 2. System parts are considered as permanently tight, when: a. they are designed so that they remain tight due to their construction, or b. their technical impermeability is continuously guaranteed through maintenance and monitoring. 3. System parts, which are permanently tight, due to their construction, do not cause any potentially explosive areas in their surroundings in the unopened state. German Agricultural Occupational Health and Safety Agency 58 Appendix 10 4. Permanently tight system parts and equipment parts according to Section 2 a) are, e.g.: 1. Welded system parts with: a. detachable components, where the detachable connections required for this are only rarely detached during operation and are constructively formed like the detachable pipe connections described below (exception: metallic sealing connections), b. detachable connections to pipelines, fixtures, or temporary covers, where the detachable connections required for this are only rarely detached during operation and are constructively formed like the detachable pipe connections named below 2. Shaft feed-through with double-acting slide ring seals (e.g., pumps, agitators). 3. Canned motor pumps. 4. Magnetically coupled packing-less pumps. 5. Fixtures with seals of the stem extension by means of bellows and safety joints, stuffing box joint seals with self-adjusting sealing material. 6. Fixtures without packing box with permanent magnetic drive. 5. Permanently tight pipeline connections according to Section 2 a) are, e.g.: 1. Non-detachable connections, e.g., welded. 2. Detachable connections, which are only rarely detached during operation, e.g.: • flanges with welded lip seals • flanges with groove and tongue • flanges with projections and recesses • flanges with V-grooves and V groove seals • flanges with smooth raised sealing face and special seals, soft materials seal up to PN 25 bar, metal interior edge contained seals or metal clad seals, if with use of DIN flanges a rated verification has sufficient reliability against the yield strength. 6. Permanently tight connections according to Section 2 a) for connecting fix- tures are, as long as they are only rarely detached, e.g.: 1. the pipeline connections named above, and 2. NPT-threads (National Pipe Taper Thread, tapered pipe thread) or other conical pipe thread with seals in the threads up to DN 50, as long as they are not used with alternating thermal loading (∆t > 100° C). German Agricultural Occupational Health and Safety Agency 59 Appendix 10 7. Along with the purely constructive measures, according to Section 2 b), technical measures can also be combined with organizational measures to achieve a permanently technical tight system part. Among these are, with monitoring and maintenance, e.g.: 1. dynamically stressed seals, e.g., with shaft feed-through at pumps, 2. thermally stressed seals at system parts. 8. The extent and frequency of the monitoring and maintenance conform in detail to the type of the connection and construction, mode of operation, stress, as well as the state and properties of the materials. It should guarantee the permanent technical tightness. It should be noted that the extent and frequency for the monitoring and maintenance for maintaining the permanent technical tightness are specified in the Explosion Protection Docu- ment or the documents referred to there, e.g., in the associated operating instructions or in the maintenance plan. 9. For monitoring, one of the following measures can be sufficient: 1. Inspecting the system and checking, e.g., for flow marks, ice formation, odour, and noise as a consequence of leaks. 2. Inspecting the system with mobile leak detecting devices or portable gas detecting devices. 3. Continuous or periodic monitoring of the atmosphere by automatic, permanently installed measurement devices with alarm function. Tip System parts with the classification of 0.5 or 1 according to TRGS 420-Appendix 1 are considered permanently tight. Note Suitable preventive maintenance can reduce the extent and frequency of monitoring for tightness. 1.2 Tight System Parts 1. With system parts that are tight, infrequent releases are to be expected. 2. System parts are considered tight when no leaks can be detected with a tightness test suitable for the application, or tightness monitoring or tightness inspection, e.g., with foam forming agents or with leak detection devices or leak indicator devices. German Agricultural Occupational Health and Safety Agency 60 Appendix 10 3. Examples of tight system parts are: 1. Flange with smooth raised face and no special constructive requirements of the seal. 2. Cut and clamp connections in cables larger than DN 32. 3. Pumps whose tightness depends only on a simply acting slide ring seal. 4. Detachable connections according to No. 1.1, which are only rarely disconnected. 1.3 Minimizing Operational Discharge of Combustible Substances 1. Outside of system parts, which are neither permanently tight nor tight, the formation of a hazardous, potentially explosive atmosphere through operational discharges of combustible liquids, gases, steam, or dust must be expected. Note 1 Operational discharge locations are, e.g., ventilation and relief lines, fluid transfer connection points, manual outlet valves, sampling points, drainage installations, and with dust, e.g., transfer points. Note 2 Other possible discharge points are flange or gas dome connections that are not controlled (e.g., pump housings). 2. Through technical measures, the quantities discharged, the zone extension, or the likelihood of the discharge of potentially explosive atmospheres can be reduced, if, e.g.: 1. a complete hose system is used during fluid transfer, 2. fluid transfer is performed in closed systems using the gas return, 3. ventilation and relief lines are routed into the gas collecting system, 4. it is guaranteed by using special equipment that only small quantities can escape at sampling points and manual outlet valves, 5. drains are implemented via sluices of low capacity with mutually locking shutoff valves, 6. the transfer points of dusty or dust-containing products are provided with a flexible encasement made of largely dust impermeable materials, 7. at operational discharge locations, a discharge of combustible substances can be avoided through low-pressure operation mode, German Agricultural Occupational Health and Safety Agency 61 Appendix 10 8. with the use of the low-pressure operation mode (e.g., 900 mbar abs.) the likelihood of a discharge of a hazardous, potentially explosive atmosphere near the system parts (e.g., openings, shaft feed-through) is very low. 1.4 Testing the System Parts for Tightness Systems according to 1.1, Section 2 a), must be tested for tightness as a whole or in sections before beginning operation for the first time, as well as after longer interruptions in operation, changes, and repair or large scale retrofitting. Tight systems and systems according to 1.1, Section 2 b), must be tested for tightness additionally on a regular basis according to their test schedule. German Agricultural Occupational Health and Safety Agency 62 Appendix 11 Additional Regulations and Rules Accident Prevention Regulations (VSGen) of the Agricultural Occupational Health and Safety Agency VSG 1.1 General Regulations for the Protection of Health and Safety VSG 1.4 Electrical Systems and Operating Resources VSG 2.1 Workplaces, Structural Systems, and Equipment VSG 2.2 routes legal an safety gas own performed safety escape Additional biogas the components the (emergency monitoring, of all and by sensors, digester ignition the their pump inspection/test equipment the plans. need to of work their Condensate the respective standards the inspection to drives test level test own with of inspection of Name material the EX-zone 1. with present 2. devices are 3. submerged 4. EX-zone present EX-zone Operator’s Check 5. test 6. protection 7. Check 8. emergency according of corresponding and 9. Visual Electrical Functional trol system, Functional and the Automation technology fill of German Agricultural Occupational Health and Safety Agency 67 Appendix 12 Tightness Test for Gas-Carrying Container Parts and the Gas Storage 1. Tightness Test In principle, gas-carrying container parts and gas storage can have a low permeability for gaseous substances. Therefore, the test of the technical tightness must be carried out through verification that no significant leak points are present (direct tightness test), or through verification that the leakage rate does not exceed a permissible limit value (indirect tightness test). The direct tightness test represents a practical, reliable test method, especially for biogas systems operated with the maximum operational pressure of 5 mbar, (membrane domes, and membrane storage bags). The indirect tightness test yields reliable results with rigid enclosed biogas systems, which are operated at higher operational pressures and have only very low gas temperature fluctuations in the gas room. 1.1 Direct Tightness Test 1.1.1 Test Pressure For testing the technical tightness, the digester, gas-carrying container, and gas storage must be subjected to a sufficient test pressure so that an escape of gas through a leakage point can be caused. In principle, the test must be performed with 1.5 times the maximum permissible operating pressure. If this is not inherently possible for the system (e.g., with freestanding elastomer single membrane dome gas storage systems) the test must be performed with the maximum permissible operating pressure. 1.1.2 Test Media Preferably, air is used as a test media for systems that have not yet begun operation. If the tightness test is to be performed in systems that have already begun operation, as a rule, gas detectors must be used, which can safely detect methane, in particular, in the measurement range of 0 to 1% vol. Fog forming agents that are introduced into the gas phase have also proven useful for the detection of leaks. 1.1.3 Tightness Test The direct tightness test can be performed as a visual inspection with a foam-forming agent, with fog generating agents, or as a test with a gas detector. In particular, the wall connection of container coverings and the connection nozzles, which are located in the gas area of the container, must be tested for tightness. German Agricultural Occupational Health and Safety Agency 68 Appendix 13 1.2 Indirect Tightness Test 1.2.1 Test Pressure For testing the technical tightness, the digester, gas-carrying container and gas storage must be subjected to a sufficient test pressure so that an escape of gas through a leakage point can be caused. In principle, the test must be performed with 1.5 times the maximum permissible operating pressure. If this is not inherently possible for the system, the test must be performed with the maximum permissible operating pressure. 1.2.2 Permissible Leakage Rate The permissible leakage rate includes the losses as a result of the permeability, e.g., of membranes and their fastening components, as well as all seals mounted on the biogas container. With respect to the possible measurement accuracy under normal operating conditions with a test pressure of 20 hPa, the permissible leakage rate amounts to: up to 50 m³ nominal capacity 0.4 m³/24h up to 100 m³ nominal capacity 0.6 m³/24h If the measurement occurs with a test pressure other than 20 hPa, the permissi- up to 200 m³ nominal capacity 0.8 m³/24h ble leakage rate must be multiplied by the factor X = test pressure/20 hPa. up to 500 m³ nominal capacity 1.0 m³/24h above 500 m³ nominal capacity 2% vol. nominal capacity/24h If the measurement occurs with a test pressure other than 20 hPa, the permissi- ble leakage rate must be multiplied by the factor X = test pressure/20 hPa. 1.2.3 Tightness Test For the indirect tightness test, the gas container is placed under test pressure, and the volume loss over the duration of the test period (creep testing) is deter- mined. Derived from the state equation of gases, the following applies for the volume loss ∆VN: ∆VN = VA * pA/pN * TN/ TA - VE * pE/pN * TN/ TE where: • VA/E = volume of the enclosed gases at • pN = standard pressure = 1013.25 hPa start of measurement/end of • TA/E = absolute temperature at start of measurement measurement/end of measurement • pA/E = atmospheric pressure + test • TN = standard temperature = 273.15 K pressure at start of measurement/end of measurement German Agricultural Occupational Health and Safety Agency 69 Appendix 13 The leakage rate is obtained by dividing the volume losses ∆VN by the measurement time. Depending on the possible ways to perform the measurement determined by the construction type of the biogas container, the volume loss can be determined in two different ways: • Measurement of the change of volume with a constant test pressure • Measurement of the change of test pressure with a constant volume (VA = VE) During the test period, the test gas quantity enclosed in the gas container is subjected to the following ambient conditions that cannot be influenced, such as temperature change and change of the atmospheric pressure, which exert the following influence on the test gas quantity: • at constant test pressure: 3.5% volume change per degree K of temperature change • at constant test volume: 3.5 hPa test pressure change per degree K temperature change • at constant test pressure: 1% volume change per degree hPa of atmospheric pressure change • at constant test volume: 1 hPa test pressure change per hPa atmospheric pressure change For the measurement verification of the maximum leakage rates, specified in Section 1.2.3, it is recommended to minimize the above-named influences by using the smallest possible quantity of test gas. If a complete filling of the biogas container is necessary for generating the test pressure, such that a volume dilation of the test gas is not possible, the maximum permissible overpressure of the container must not be exceeded during the test. The duration of the test period must be defined such that the leakage rate can be determined clearly outside the measurement error limits. For this, the measurement errors for the measurement of volume, test pressure, atmospheric pressure, and temperature must be considered. It is recommended to measure the temperature at a time when the temperature of the biogas container is not changed by solar radiation. The most favourable time to perform the measurement is in the morning before the start of the solar radiation. A measurement time period of 24 hours is recommended. If the measurement cannot be performed due to the type of construction of the biogas container, the biogas container is considered not tight. Supplementary protective measures must be deployed. German Agricultural Occupational Health and Safety Agency 70 Appendix 14 Information of the Property Insurer Information on Damage Prevention from the Perspective of Material Asset Protection (Informative) The following information provides further measures to prevent material damage, supplementing the safety rules for biogas systems that are primarily aimed at personal protection. They have been developed by experts of the German Insurance Association (GDV) based on damage experience. They are intended to prevent or limit material damage. This information is nonbinding. The insurance underwriter can also accept different safety provisions and measures in individual cases depending on the risk conditions and the risk assessment. 1. Fire Protection 1.1 Building Fire Protection Systems and equipment that are important for the operation, e.g., machine room (CHP unit), control room, process control, as well as operating areas with increased risk of fire, e.g., work shop, must be separated in a fire resistant manner from the adjacent building areas, in order to prevent the spread of damage as much as possible. Rooms are considered separated in a fire resistant manner if they are enclosed by fire resistant ceilings and walls with fire resistant partitions of existing openings. Suitable fire alarm devices in the machine room should be able to detect excessive temperatures early. Thus, potential fires can be contained at an early stage. Tip VdS 195 “Technical Guidelines for the Fire Insurance and the Insurance of Operating Disruption due to Fire; Risks, Protection Goals, Protection Concepts, And Protection Measures”; VdS 2095 “VdS Guidelines for Automatic Fire Alarms; Planning, and Installation” 1.2 Protection of Electrical Equipment • The electrical equipment must be constructed according to the accepted rules of electrical engineering (Regulation of the Association of Electrical Engineering, Electronics, and Information Technology, VDE e.V.) German Agricultural Occupational Health and Safety Agency 71 Appendix 14 • The electrical equipment must be tested before being taken in operation and must be maintained in good condition according to the legal and regulatory safety ordinances, as well as according to the VDE regulations. If deficiencies occur, they must be remediated immediately by electrical specialists. Tip VdS 2046 “Safety Regulations for Systems up to 1000V”, BGV A3 “Electrical Systems and Resources”, VSG 1.4 ““Electrical Systems and Resources” • If over voltage protections are missing, over voltage due to lightning strikes or other causes can lead to damage of the system control and to disruptions of the operation. Therefore, over voltage protection (internal lightning arrestor) and consistent potential equalization are required for the electrical equipment and for electronic control, data processing, and telecommunication systems. The network form as a 5-conductor network (TN-S System) in conjunction with the potential equalization serves to avoid equalizing current. For larger systems, measures of the lightning protection Cass III may be required. Tip VdS 2017 “Lightning and Over voltage Protection for Agricultural Operations” and VdS 2010 “Risk Oriented Lightning and Over voltage Protection, Guidelines for the Prevention of Material Damage” 1.3 Organizational Fire Protection • Work representing a potential fire hazard is permitted only with written permission by the management of the organization (permit procedure for work involving fire hazards). Tip VdS 2008 “Work with Fire Hazards, Guidelines for Fire Protection” • Fire extinguishers of the fire classes A, B, and C according to DIN EN 3 must be installed at suitable locations and must be maintained in operational working condition. Tip Workplace Guideline “ASR 13/1.2 Fire Extinguishing Equipment” German Agricultural Occupational Health and Safety Agency 72 Appendix 14 • Containers with fresh oil and used oil must be stored outside the machine room if they are not procedurally integrated. • Oil catch basins below the motors must be emptied and cleaned regularly. Tip VdS 2000 “Guideline for Fire Protection during Operation” 2. Operation of Machines and Equipment 2.1 CHP unit • Depending on the contents of hydrogen sulphide and/or silicon compounds, the lubrication properties of the motor oil can be reduced, or deposits at pistons, bushings, and valves can cause abrasive processes (increased wear). Both effects can lead to substantial damage. • Therefore, the gas quality should be monitored continuously. Through appropriate gas cleaning, the contaminants can be removed in order to prevent damage and premature wear. The manufacturer’s specification must be followed. • With pilot injection engines, too small a quantity of pilot fuel can lead to an insufficient cooling of the injection valves. Therefore, the injection valves must be checked every 1200 to 1500 operating hours and changed if necessary. Dripping injection valves lead to serious damage at the pistons and bushings. This can result in potentially serious engine problems. • An effective method to monitor the respective combustion chamber temperatures is a measurement with an alarm trigger for each cylinder. This way, damage due to overheating can be prevented through timely shut off. • Gas motors can be adapted to lower quality gas with lower methane content through changes of the ignition point. Here, a knocking of the engine is generally not expected (biogas has a high knock resistance), unless the system is operated in a bivalent mode with liquid gas. • Motors suited for biogas also have in individual cases still small amounts of non-ferrous metals (piston rod bearing bushing, oil cooler, camshaft bearing, etc.) and, therefore, are susceptible to acids. If the specified gas and oil qualities are not maintained, the motors can fail due to repairs already long before the scheduled larger service. • For buffering of acids, for instance, the motor oil volumes can be increased. This way, potential contaminants are thinned. The oil change schedules and the oil qualities specified by the manufacturer must be German Agricultural Occupational Health and Safety Agency 73 Appendix 14 maintained. With increasing acid content, the motor oil loses its lubrication properties. Therefore, it is recommended that oil analyses adapted to the operating conditions be performed, with determination of the TAN value (total acid number). The results should be documented, and the intervals should be adapted accordingly. • The exhaust system should be constructed from welded (not inserted or clamped) stainless steel pipes. Exhaust gas lines must lead the exhaust gases away hazard free. A distance of at least 20 cm to flammable building materials must be maintained. • Feed and return lines of lubrication oil of the turbo charger should be checked regularly for tightness through visual controls. • If the manufacturer does not specify service intervals, for gas motors, the following must be performed every • 20,000 operating hours – a partial reconditioning (check: cylinder head, turbo air cooler, piston rod bearings, pistons, and running bushings; exchange depending on wear; and every • 40,000 operating hours – a fundamental reconditioning, with exchange of all wear parts (generators, agitators, and separators must be included), • for pilot injection motors, every 15,000 operating hours – a partial reconditioning, and every 30,000 operating hours – a fundamental overhaul. For the CHP unit, a service schedule must be created in which all checks to be performed and all service intervals are specified. Tip Renewable Energy, Complete Overview of the Technical State of the Art and the Potential Danger, Status: March 2008, page 387. Free download at: www.gdv.de/Themen/SchadenundUnfallversicherung AllgemeineHaftpflicht- versicherung/inhaltsseite17075.html 2.2 Digester Container • Digester containers made of concrete must be built with sulphate resistant cement. The concrete should have the strength class C30/37 (B35) or higher. • Above the area always covered by the substrate, the container should be protected additionally through a coating or cladding. In this area, sulphur deposits occur that attack the construction substance. • The motor of the agitator must be protected by a motor protection circuit. In order to avoid cable breaks, the cables should be replaced at regular intervals. German Agricultural Occupational Health and Safety Agency 74 Appendix 14 It is recommended to use only winch capable cables of the V4A quality. Iron II chloride for buffering the acid can to corrode stainless steel if it is not dosed op- timally. A failure of the agitator technology (cables, propeller) can result. 2.3 System Control • If EC (Electro-Chemical) sensors are used for the gas analysis, they must be exchanged regularly due to their increased wear. • The pH sensor and the temperature sensor should be replaced once a year to increase the reliability of the measurements. • A maintenance contract for the components of the system control must be negotiated. • If the system is not constructed by a general contractor, the interfaces between the individual system parts must be defined and documented accordingly. • It must be guaranteed through appropriate measures (possibly through filters), that only clear air is fed to the machine room/the control room. 3. Environmental Protection, Aspects of Environmental Hazards The construction and the operation of the biogas system must first occur in such a manner that people and the environment is impacted as little as possible. For this purpose, it is necessary that the relevant laws (e.g., Federal Construction Law [BBauGB], Federal Emission Protection Law [BimSchG] in conjunction with the corresponding regulations, Water Management Law [WHG], Fertilizer Law [DüngeMG], Fertilizer Ordinance [DüngeVO][ MinöStG], Hygiene Regulation, (Petroleum Tax Law), as well as possible changes in the law, should always be heeded. 3.1 Water Protection • According to the water management law [WHG], systems for storing and processing liquid manure and slurry must be constructed such that a contamination and endangerment of water bodies cannot occur. The systems must be constructed and operated according to the acknowledged rules of technology. • The stability of the containers for fermentation and final storage must be verified through tests. • In Zones I and II of water protection areas, the construction of systems for storing and processing of liquid manure and slurry is not permitted. German Agricultural Occupational Health and Safety Agency 75 Appendix 14 • Systems for storing and processing of liquid manure and slurry must main- tain a distance of at least 20 m from above ground water bodies, as well as runoff ditches, roadside ditches, etc., that do not carry water continu- ously. 3.2 Recovery of Recycling Material • With the recycling of the final substrate, it must be assured that it remains as pollutant-free as possible. It can be problematic to apply it as fertilizer for acreage that is used for agriculture or horticulture if co-ferments are used whose composition and degradation have not been analyzed sufficiently. • In order to prevent possible damage of the acreage or the crop products with the recycling of the final substrate, a regular analysis according to the fertilizer ordinance/biowaste ordinance should be performed by accredited laboratories (e.g., by laboratories designated by government agencies according to the biowaste ordinance). If liquids are dispersed into open waters, regular assessments should be performed to prevent damage. Appropriate monitoring is extremely helpful to defend against claims that may be registered only later. 4. Insurance The insurance of biogas systems requires special coverage concepts that go beyond the typical agricultural property and public liability insurance. For instance, the technical operational risk can be secured by a machinery failure insurance and machine service interruption insurance; the environmental risk can be secured by environmental liability insurance and the environmental damage insurance. An inspection of the biogas system by the insurer for the correct determination of the risk and for specifying the required insurance protection should be a normal course of action for the system operator as well as the insurer. Contact your insurer to resolve questions or to seek clarification. The technical publications of the insurance industry mentioned in the text can be obtained from: VdS-Verlag Amsterdamer Straße 174 50735 Köln Germany German Agricultural Occupational Health and Safety Agency 76 Contacts Landwirtschaftliche Berufsgenossenschaft Schleswig-Holstein und Hamburg [Agricultural Occupational Health and Safety Agency Schleswig-Holstein and Hamburg] Schulstraße 29 24143 Kiel, Germany Telephone 0431 7024-0 Fax 0431 7024-6120 Email post@kiel.lsv.de Landwirtschaftliche Berufsgenossenschaft Niedersachsen-Bremen [Agricultural Occupational Health and Safety Agency Lower Saxony-Bremen] Im Haspelfelde 24 30173 Hannover, Germany Telephone 0511 8073-0 Fax 0511 8073-498 Email info@nb.lsv.de Landwirtschaftliche Berufsgenossenschaft Nordrhein-Westfalen [Agricultural Occupational Health and Safety Agency North Rhine-Westfalia] Hoher Heckenweg 76-80 48147 Münster, Germany Telephone 0251 2320-0 Fax 0251 2320-554 Email mailbox@nrw.lsv.de Land- und forstwirtschaftliche Berufsgenossenschaft Hessen, Rheinland-Pfalz und Saarland [Agricultural and Forestry Occupational Health and Safety Agency Hessen, Rhineland Palatinate and Saarland] Bartningstraße 57 64289 Darmstadt, Germany Telephone 061 51 702-0 Fax 061 51 702-1260 Email info.da@hrs.lsv.de Land- und forstwirtschaftliche Berufsgenossenschaft Franken und Oberbayern [Agricultural and Forestry Occupational Health and Safety Agency Franconia and Upper Bavaria] Dammwäldchen 4 95444 Bayreuth, Germany Telephone 0921 603-0 Fax 0921 603-386 Email kontakt@fob.lsv.de German Agricultural Occupational Health and Safety Agency 77 Contacts Land- und forstwirtschaftliche Berufsgenossenschaft Niederbayern/Oberpfalz und Schwaben [Agricultural Occupational Health and Safety Agency Lower Bavaria Upper Palatinate and Schwabia] Dr.-Georg-Heim-Allee 1 84036 Landshut, Germany Telephone 0871 696-0 Fax 0871 696-488 Email lsv@landshut.lsv.de Landwirtschaftliche Berufsgenossenschaft Baden-Württemberg [Agricultural Occupational Health and Safety Agency Baden-Württemberg] Vogelrainstraße 25 70199 Stuttgart, Germany Telephone 0711 966-0 Fax 0711 966-2140 Email post@bw.lsv.de Landwirtschaftliche Berufsgenossenschaft Mittel- und Ostdeutschland [Agricultural Occupational Health and Safety Agency Central and East Ger- many] OT Hönow Hoppegartener Straße 100 15366 Hoppegarten, Germany Telephone 03342 36-0 Fax 03342 36-1230 Email mail@mod.lsv.de Gartenbau-Berufsgenossenschaft [Horticultural Occupation Health and Safety Agency] Frankfurter Straße 126 34121 Kassel, Germany Telephone 0561 928-0 Fax 0561 928-2486 Email info@gartenbau.lsv.de Publisher: Bundesverband der landwirtschaftlichen Berufsgenossenschaften Weißensteinstraße 70-72 34131 Kassel, Germany www.lsv.de Status: 10/2008 German Agricultural Occupational Health and Safety Agency 78 This translation is made possible by the following organizations: • German Agricultural Occupational Health and Safety Agency • Ontario Ministry of Agriculture, Food and Rural Affairs • PlanET Biogas Solutions • BioEN German Agricultural Occupational Health and Safety Agency APPENDICES APPENDIX F – BIOGAS SAFETY FIRST, GUIDELINES FOR THE SAFE USE OF BIOGAS TECHNOLOGY, BIOGAS KNOW- HOW_2, GIZ DEUTSHCE GESELLSHAFT FÜR INTERNATIONALE ZUSAMMENARBEIT (GIZ) GMBH, AND FACHVERBAND BIOGAS (GERMAN BIOGAS ASSOCIATED), NOVEMBER 2016) BIOGAS Safety first! Guidelines for the safe use of biogas technology Know-how_2 BIOGAS

Hazard pictograms

M » M Ä

Signal word

Danger

Hazard statements

H290 - May be corrosive to metals. H302 - Harmful if swallowed. H315 - Causes skin irritation. H318 - Causes serious eye damage.

Prevention

P280 - Wear protective gloves and eye or face protection. BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 2. Hazards identification (continued)

Response

P301+P312 - IF SWALLOWED : Call a POISON CENTER or doctor if you feel unwell. P302+P352 - IF ON SKIN : Wash with plenty of soap and water. P305+ P351+P338 - IF IN EYES : Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. P310 - Immediately call a POISON CENTER or doctor. - Disposal considerations : P501 - Dispose of this material and its container to hazardous or special waste collection point.

Other physicochemical hazards

When contact with metals corrosion may occur and generate extremely flammable hydrogen gas. The substance decomposes by heating or burning in formation of toxic and corrosive vapours. Hazards for the health : A health dangerous concentration in the air will not or very slowly be reached by evaporation of this substance at app. 20°C; by spraying much faster. Hazards for the environment : Product causes a strong drop of the pH-value of water and soil. This product is no substance or contains no PBT or vPvB (in accordance with Annex XIII). Hazards for the safety : No significant danger. SECTION 3. Composition/information on ingredients 3.2. Mixtures * HARMFUL COMPONENT(S) Name component(s) Weight % CAS nr EINECS nr Index nr Reach nr

2.1 Classification of the substance or mixture

Ferric chloride 39 -41 % 7705-08-0 231-729-4 ----- 01-2119497998-05 Xn; R22 Xi; R38-41 ---------------------------------- Acute Tox. 4 (oral); H302 Skin Irrit. 2; H315 Eye Dam. 1; H318 Hydrochloric acid ...% 1 -2 % 7647-01-0 231-595-7 017-002-01-X 01-2119484862-27 C; R34 Xi; R37 ---------------------------------- Met. Corr. 1; H290 Skin Corr. 1B; H314 STOT SE 3; H335 The full text of the R-phrases and (EU)H-statements is in section 16. Note B (Regulation (EC) No 1272/2008) applies to the product or one or more of its components. Note: SCL applicable ( Hydrochloric acid ...%) SECTION 4. First aid measures 4.1. Description of first aid measures General : CALL A PHYSICIAN IN ALL CIRCUMSTANCES. Never give anything by mouth to an unconscious person. First Aid Measures - Inhalation : Remove victim into fresh air. Allow the affected person to rest in semi-sitting position. If not breathing, give artificial respiration. Consult a doctor. BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 4. First aid measures (continued) * - Skin Contact : Remove contaminated clothing. Rinse skin immediately with mild soap and plenty of water. (shower if necessary). Consult a doctor. - Eye Contact : Rinse immediately thoroughly and long (at least 15 min.) with plenty of water. Remove contact lenses. Take to eye doctor afterwards. Keep rinsing or dripping the eye during transport. * - Ingestion : DO NOT INDUCE VOMITING. Rinse mouth with water. Call a POISON CENTER or doctor/physician if you feel unwell. 4.2. Most important symptoms and effects, both acute and delayed See section 11. 4.3. Indication of any immediate medical attention and special treatment needed For specialist advice doctors should contact the NVCI or the Belgian Poison center. SECTION 5. Firefighting measures 5.1. Extinguishing media Extinguishing Media - Suitable : Extinguishing powder , Foam , Carbon dioxide (CO2) , Water spray . * - Insuitable : Heavy water stream . 5.2. Special hazards arising from the substance or mixture Special Exposure Hazards : Fire may liberate toxic and stinging vapours. ( E.g. Chlorine , Hydrogen chloride ). 5.3. Advice for firefighters Special Protective Equipment for : Use self-contained breathing apparatus and wear protective clothes when in close Firefighters proximity to fire. Special Procedures : Apply water spray or fog to cool nearby equipment. Avoid fire-fighting water to enter environment. SECTION 6. Accidental release measures 6.1. Personal precautions, protective equipment and emergency procedures Personal Precautions : Evacuate all personnel immediately and ventilate area. Avoid breathing vapour and contact with skin, eyes and clothing. Wear recommended personal protective equipment. (See section 8) 6.2. Environmental precautions Environmental Precautions : Shut off leaks if without risks. Dike in the spilled product as much as possible with inert material. Prevent entry of product in public water, sewers or soil. Notify authorities if product enters sewers or public waters. 6.3. Methods and material for containment and cleaning up Methods for Cleaning Up : Collect the spillage in closable, suitable disposal containers. Clean up any spills as soon as possible, using an inert absorbent material. Dilute spilled liquid immediately with plenty of water and neutralise with base. 6.4. Reference to other sections For personal protection, see section 8. For the removal of the waste product, see section 13. BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 7. Handling and storage 7.1. Precautions for safe handling * Handling : STRONG HYGIENE ! AVOID FOG TRANSFORMATION ! Avoid breathing vapour and contact with skin, eyes and clothing. Wear recommended personal protective equipment. (See section 8) Avoid heating, splashing and formation of vapour when emptying, pouring, diluting or dissolving the product. When using, do not eat, drink or smoke. Emergency eye wash fountains and showers should be available in the immediate vicinity of any potential exposure. 7.2. Conditions for safe storage, including any incompatibilities Code Part 15, but where additional measures are required to minimise the risk of fire. For the purposes of fixed electrical equipment the ‘Protected Area’ is treated as a Zone 2 Area and is derived from UKLPG CoP safety distances. All electrical equipment permanently installed within the Protected Area should conform to the requirements of:- “Equipment Group II, Category 3, “G” of the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmosphere Regulations 1996”. 4.8 Derived Graphs Graphs produced from Tables C9 to allow extrapolation of data to be undertaken. 4.9 Fixed Electrical Equipment Installed within Zone 1, Zone 1T, Zone 2 or Zone 2T Hazardous Areas shall be certified as follows:- Equipment Group; II, Equipment Category Zone 1: 2 G Equipment Category Zone 2: 3 G or 2 G Apparatus / Gas Group: IIA Temperature Class: T2 – suitable for Butane & Propane gas 4 of 6 6 x 2 tonne Pumped Liquid Propane Issue 1 –July 2017 METHODOLGY USED TO DETERMINE THE CLASSIFICATION OF THE SITE ITEM AREAS METHODOLOGY ADOPTED Reference Release Hazardous PRESENT Sections in Grade Radii Code R¹ (Metre) Hydrostatic Pipework These are small capacity pressure relief valves protecting pipework Table C9 Secondary R¹ 0.5 Relief Valves and/or hoses and should not operate under normal working conditions. And R² 0.5 The devices are changed on a regular basis, every ten years, as part of UKLPG the installation maintenance plan and Written Scheme of Examination Guidance (PSSR) LPG Land based Pump Skid Unit IP Guidance indicates a Primary radius of 0.3 metres and the AEGPL AEGPL Primary Pumps Guidance indicates a Primary radius of 0.5 metres, therefore the greater R¹ 0.5 figure has been used. R² 0.5 Liquid Transfer Road Tankers Hoses are subject to very careful maintenance and inspection. Hoses Consequently, under normal circumstances hoses would not be expected to be a source of leakage and for this reason the leakage from the hose itself has been discounted in this exercise. Relief Valves

Storage

Keep only in the original, safely locked container in a well ventilated, cool and dark place. All dangerous products should be placed on a drip tray or should be barreled. Keep away from : Bases , Light metals , Halogenated hydrocarbons . Packaging Material : Polyethylene , Polypropylene , PVC , Polyester , Glass . Insuitable Packaging Material : Light metals ( Aluminium , Copper , Iron , Tin , Nickel ). 7.3. Specific end use(s) For identified uses, see subsection 1.2 and/or exposure scenarios. SECTION 8. Exposure controls/personal protection 8.1. Control parameters * Occupational Exposure Limits : For harmful components : Ferric chloride Limit value (BE) 1 mg Fe/m³ (2014) Hydrochloric acid ...% Limit value (BE) 5 ppm (8 mg/m³) (2014) Hydrochloric acid ...% Short time value (BE) 10 ppm (15 mg/m³) (2014) Hydrochloric acid ...% Limit value (TWA 8 h) (NL) 5 ppm (8 mg/m³) (2007) Hydrochloric acid ...% Limit value (TWA 15 min) (NL) 10 ppm (15 mg/m³) (2007) Biological limit values : They will be included when available. DNELs : For harmful components : Ferric chloride Worker, acute - systemic effects, inhalation 5,9 mg/m³ Ferric chloride Worker, acute - systemic effects, dermal 1,7 mg/kg bw/ day Ferric chloride Worker, long-term - systemic effects, inhalation 5,9 mg/m³ Ferric chloride Worker, long-term - systemic effects, dermal 1,7 mg/kg bw/ day Ferric chloride Consumer, acute - systemic effects, inhalation 0,5 mg/m³ Ferric chloride Consumer, acute - systemic effects, dermal 0,29 mg/kg bw/ day Ferric chloride Consumer, acute - systemic effects, oral 0,29 mg/kg bw/ day Ferric chloride Consumer, long-term - systemic effects, inhalation 0,5 mg/m³ Ferric chloride Consumer, long-term - systemic effects, dermal 0,29 mg/kg bw/ day Ferric chloride Consumer, long-term - systemic effects, oral 0,29 mg/kg bw/ day Hydrochloric acid ...% Worker, acute - local effects, inhalation 15 mg/m³ Hydrochloric acid ...% Worker, long-term - local effects, inhalation 8 mg/m³ PNECs : For harmful components : Ferric chloride Fresh water sediment 49500 mg/kg Ferric chloride Marine water sediment 8 mg/m³ Ferric chloride Soil 55000 mg/kg Ferric chloride Sewage treatment plant 1455 mg/l Hydrochloric acid ...% Fresh water sediment Not relevant Hydrochloric acid ...% Marine water sediment Not relevant Hydrochloric acid ...% Fresh water 0,036 mg/l Hydrochloric acid ...% Marine water 0,036 mg/l Hydrochloric acid ...% Soil 0,036 mg/l Hydrochloric acid ...% Intermittent release 0,045 mg/l BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 8. Exposure controls/personal protection (continued) Hydrochloric acid ...% Sewage treatment plant 0,036 mg/l 8.2. Exposure controls Engineering Measures : Ventilation , Local exhaust . Personal Protection Equipment - Respiratory protection : CE-approved mask for acid gases and vapours (type E, yellow). - Skin protection : Corrosion-proof protective clothing. * - Hand protection : Suitable material for safety gloves (EN 374): As the product is a mixture of several substances, the durability of the glove materials can't be calculated in advance and has to be tested before use. - material : PVC - thickness : 0,7 mm - breakthrough time > 480' - material : Neoprene , Nitril rubber - thickness : 0,5 mm - breakthrough time : > 480' - Eye/Face protection : Closed safety glasses or face shield. Environmental exposure controls : See sections 6, 7, 12 and 13. SECTION 9. Physical and chemical properties 9.1. Information on basic physical and chemical properties Physical State (20°C) : Liquid . Form/Colour : Dark brown . Odour : Pungent odour . Odour threshold : No data available. pH value : < 1 Melting/Freezing point : -50 °C Boiling Point/Range (1013 hPa) : 100 - 105 °C Flash point : Not applicable. Fire hazard : Not applicable. Evaporation rate : No data available. Explosion limits in air : Not applicable. Vapour pressure : No data available. Relative density : 1,4 Density (20°C) : 1,41 - 1,45 kg/l (40% sol. ) Solubility in water : Complete solubility Log P Octanol/Water (20°C) : -4 Auto-ignition temperature : No data available. Minimum ignition energy : Not applicable. Decomposition temperature : 315 °C * Viscosity (20°C) : 5 - 20 mPas ( Dynamic ) Explosive properties : No chemical groups associated with explosive properties . Oxidizing properties : No chemical groups associated with oxidizing properties . SECTION 10. Stability and reactivity 10.1. Reactivity BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 10. Stability and reactivity (continued) Reactivity : Reacts violently with lyes. 10.2. Chemical stability Stability : Stable at normal circumstances . 10.3. Possibility of hazardous reactions Hazardous reactions : Contact with metallic substances may release inflammable hydrogen gas. Creation of: Hydrochloric acid ). 10.4. Conditions to avoid Conditions to avoid : High temperatures , Freezing . 10.5. Incompatible materials Materials to avoid : Bases , Light metals , Halogenated hydrocarbons , Metals . 10.6. Hazardous decomposition products Hazardous Decomposition Products : Chlorine , Hydrogen chloride , Hydrogen gas . Facilities VSG 2.8 Storage of Liquid Manure, Pits, Canals, and Wells Information CD – Prevention at a Glance Source: The VSGen can be requested at any of the responsible Agricultural Occupational Health and Safety Agencies (see the list on the last page of this brochure). All information is also available via the Inter- net at www.lsv.de. Information from the Agricultural Occupational Health and Safety Agencies: Handouts for Safety with Biogas Systems Ordinances: Ordinances concerning the protection of health and safety with the provision of work materials and their use during work, concerning safety during operation of systems requiring monitoring, and concerning the organization of the operational work safety (Ordinance on Industrial Health and Safety – BetrSichV). Ordinances of the Ministry for the Environment and Transportation concerning systems for the handling and transporting substances that are harmful to water and concerning specialist operations (System Ordinances for Substances that are Harmful to Water, VAwS), in the version of the respective Federal States in Germany. Ordinances of the Commercial Employer’s Liability Insurance Association BGR 104 Explosion Protection Rules BGR 117 Working in Containers, Silos, and Narrow Enclosures BGR 133 Equipping Workplaces with Fire Extinguishers Source: Carl Heymanns Verlag KG, Luxemburger Str. 449, 50939 Köln, Germany, or via the Internet at the website of the German Statutory Accident Insurance www.dguv.de German Agricultural Occupational Health and Safety Agency 63 Appendix 11 Government Rules (Germany) TRBS 2152 Hazardous, Potentially Explosive Atmospheres – General TRBS 2152 Hazardous, Potentially Explosive Atmospheres – Assessment of the Danger of Explosion TRBS 2152 Avoiding or Limiting Hazardous, Potentially Explosive Atmospheres TRBA 214 Waste Treatment Plants including Sorting Systems in Waste Management TRBA 230 Protective Measures during Activities with Biological Work Materials in the Agricultural and Forestry Industries with Comparable Activities TRBA 500 General Hygiene Measures: Minimum Requirements Source: www.baua.de Standards DIN 2403 Labelling of pipelines according to the material flowing In them DIN 2470 Gas lines of steel pipes with permissible operating pressures up to 16 Bar; – 1 requirements on the pipeline parts DIN 4102 Fire characteristics of construction materials and components DIN EN 13463 Non-electrical devices for use in potentially explosive areas DIN EN 13501 Classification of building products and types of buildings based on their fire characteristics DIN EN ISO Fixed access to mechanical systems 14122 Source: Beuth Verlag, Burggrafenstr. 6, 12623 Berlin, Germany VDE Regulations: [VDE – German Electrical Engineering Association] DIN 0100 Building Low Voltage Systems VDE 0165 Electrical Equipment for Potentially Explosive Gas Hazard Areas – Part 1/ Part 14: Electrical Systems in Potentially Explosive Areas (except EN 60 079-14 mining operations) VDE Electrical Equipment for Potentially Explosive Areas 0170/0171 VDE 0185- Protection from Lightning 305-1 VDI/VDE Sheet 1–3; Securing Process Engineering Systems with Means of 2180 Process Control Engineering (PLT) Source: VDE-Verlag GmbH, Bismarckstr. 33, 10625 Berlin, Germany German Agricultural Occupational Health and Safety Agency 64 Appendix 11 DVGW Rules: [DVGW – German Technical and Scientific Association for Gas and Water] G 600 Technical Rules for Gas Installations DVGW-TRGI 2008 G 262 Use of Gases from Regenerative Sources in the Public Gas Supply G 472 Gas Lines Up To Operating Pressures of 10 Bar, Composed of Polyethylene (PE 80, PE 100 and PE-Xa); Installation G 469 Compression Test Methods for Lines and Systems of the Gas Supply G 462 Part 1 Installation of Gas Lines of Steel Pipes with Operational Pressure of Up To 4 Bar G 462 Part 2 Gas Lines of Steel Pipes with Operational Pressures of More Than 4 Bar and Up to 16 Bar; Installation VP 265 ff Systems for Processing and Supplying Biogas into the Natural Gas Network Source: Wirtschafts- und Verlagsgesellschaft Gas und Wasser mbH, Postfach 14 01 51, 53111 Bonn, Germany German Agricultural Occupational Health and Safety Agency 65 Appendix 12 Test Plan for Work Material According to BetrSichV by Qualified Personnel of the Biogas System Sample (Work material= control methods) Notification acknowledged by management test Name organization qualified person of entry results, operating Test notes, comments Possible into log Deficiency immediately remediated? Yes No Deficiency detected? Yes test Last Next visual complete test section/ test pumps, test feeder pumps, test work pumps, flare, visual the of unit inspection/ in compressor Name material inspection/ 1. visual functional 2. visual functional inspection/ 3. Visual functional 4. Substrate inspection/ functional 5. visual functional 6. inspection/ functional 7. Substrate visual functional CHP Substrate Gas Emergency Agitators, Solids German Agricultural Occupational Health and Safety Agency 66 Appendix 12 Notifi- cation ac- knowl edged by man- agem ent the Name qualified person test organization of at notes, results, Test comments Deficiency immediately remediated? Yes No Deficiency detected? Yes test Last Next con- with book devices are which sources and checks electronic PPE implementation system requirements electrician function off etc.) in log switches, which in sources ignition separator and Vessel(s) All relief valves installed in these installations and road tankers are IP and Secondary R¹ 0.5 Road Tankers manufactured to approved LP Gas Industry Standards and the UKLPG requirements of UKLPG Codes of Practice. Consequently, the chance of an unexpected activation is unlikely and as a result it is justified to use the hazard radii suggested in 3.2.5. Screwed Pipework Screwed joints are allowed only on small diameter pipework, once a Connections joint has been made and proved, it remains undisturbed. Consequently, provided the pipe is correctly supported and secure there is no reason for leakage to occur. Fixed Storage Vessel(s) This is the connection on each vessel where a tanker can discharge into UKLPG Primary R¹ 1.5 Vessel Filling the installation storage vessel(s). There will be a quantity of gas release Temporary Connection on (each) disconnection and guidance supplied by UKLPG has been used to grade the release and to determine the radii. This zone will only exist during the fixed storage vessel refilling operation and has therefore been zoned Zone 1 Temporary. 5 of 6 6 x 2 tonne Pumped Liquid Propane Issue 1 –July 2017 ITEM AREAS METHODOLOGY ADOPTED Reference Release Hazardous PRESENT Sections in Grade Radii Code R¹ (Metre) Fixed Storage Vessel(s) The ullage valve/s will be used whilst the fixed storage vessel/s are UKLPG Primary R¹ 1.5 Vessel Ullage being refilled to verify the maximum filling level of product in the Temporary Valve/s vessel during the filling process. As part of its design some gas will be released, although the amount will be relatively small and under the operator’s control. All such valve/s used on the installation are of a standard design common to the LPG industry with a maximum hole size of 1.5mm and UKLPG provide guidance as to the grade and radii of the release. The zone will only exist whilst the fixed storage vessel is being refilled, therefore this has be zoned Zone 1 Temporary Valves: Vessel(s) Valves on a site tend to be used rarely or frequently. There are a Table C6 Primary Frequently Used Pipework number of valves which are used on a frequent basis (see 4.3) and these (Graph) R¹ 0.3 are liable to wear and hence gas leakage (from stems). All valves are 5.4.5.1 R² 0.3 fitted with anti blow-out stems. The Level I release frequency level has been used from Table C6 to determine the hole size for valves on the installation and foot valves (main outlet valves) on a road tanker. Valves: Vessel(s) There are valves on the installation, which are only in an emergency or Rarely Used Pipework for maintenance purposes. Consequently, these are very rarely operated and the amount of wear is therefore minimal. Even if it accepted that a small proportion of these valves might develop a leakage after use the frequency of usage and incidence of release is still very low. All valves are fitted with anti blow-out stems. Consequently, these valves not considered to be a likely sources of gas leakage and this is supported by installation operational experience. 6 of 6 RMD Consulting Engineer Limited Mobile: 07847 877 525 E-mail: rdoyle@rmdconsulting.co.uk Web page:

TOXICOLOGICAL INFORMATION

11.1. Information on toxicological effects Acute toxicity - Inhalation : Symptoms include: Sore throat , Cough . For harmful components : Ferric chloride LC50 (Rat, inhalation, 4 h) No data available Hydrochloric acid ...% LC50 (Rat, inhalation, 30') 8,3 mg/l ( Dust and fog ) - Skin contact : Symptoms include: Redness , Pain , Burns . For harmful components : Ferric chloride LD50 (Rat, dermal) >2000 mg/kg ( OECD Guideline 402) Hydrochloric acid ...% LD50 (Rabbit, dermal) >5000 mg/kg * - Ingestion : Harmful if swallowed. Symptoms include: Abdominal pain , Nausea , Vomiting , Diarrhea , Unconsciousness . For harmful components : Ferric chloride LD50 (Rat, oral) 450-900 mg/kg Hydrochloric acid ...% LD50 (Rat, oral) 238-277 mg/kg Skin corrosion/irritation : Causes skin irritation. Serious eye damage/irritation : Causes serious eye damage.

Aspiration hazard

Not considered hazardous. Respiratory or skin sensitisation : Not sensitive . Carcinogenicity : Not listed as carcinogenic . Mutagenicity : Not listed as mutagenic . Reproductive toxicity : Not listed for reproductive toxicity . Specific target organ toxicity - single : To human : Listed not for organ toxicity . exposure For animals : No effects known. Specific target organ toxicity - repeated : To human : Listed not for organ toxicity . exposure For animals : Product may affect liver, resulting in organ abnormalities.

ECOLOGICAL INFORMATION

12.1. Toxicity * Ecotoxicity : For harmful components : Ferric chloride EC50 (Daphnia magna, 48 h) 9,6 - 27,9 mg/l Ferric chloride NOEC (Algae, 72 h) 2,4 mg/l (Pseudokirchneriella subcapitata) ( BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 12. Ecological information (continued) OECD Guideline 201) Ferric chloride EC50 (Algae, 72 h) 6,9 mg/l (Pseudokirchneriella subcapitata) Ferric chloride NOEC (Daphnia magna, 21 d) 0,74 mg/l Ferric chloride LC50 (Fish, 96 h) 20,3-59 mg/l (Lepomis macrochirus) Hydrochloric acid ...% LC0 (Fish, 96 h) 20,5 mg/l (pH 3,25-3,5) Hydrochloric acid ...% EC50 (Algae, 72 h) 0,73 mg/l (pH 4,7) Hydrochloric acid ...% EC50 (Daphnia magna, 48 h) 0,45 mg/l (pH 4,9) 12.2. Persistence and degradability Persistence and degradability : For harmful components : Ferric chloride Persistence and degradability Inorganic Hydrochloric acid ...% Persistence and degradability Inorganic 12.3. Bioaccumulative potential Bioaccumulation : For harmful components : Ferric chloride Bioaccumulation Not applicable Hydrochloric acid ...% Bioaccumulation Bioaccumulation not expected 12.4. Mobility in soil Mobility : For harmful components : Ferric chloride Mobility Soluble in water Hydrochloric acid ...% Mobility Completely soluble in water

Results of PBT and vPvB assessment

Evaluation : For harmful components : Ferric chloride PBT/vPvB No Hydrochloric acid ...% PBT/vPvB No

Other hazards

Photochemical ozone creation potential : No data available. Ozone depletion potential : No data available. Endocrine disrupting potential : No data available. Global warming potential : No data available. SECTION 13. Disposal considerations 13.1. Waste treatment methods Waste from residues/Unused products : The product has to be destroyed according to national or local legislation, by a company specialised in handling hazardous waste products. European list of waste products : XXXXXX - European waste product code. This code is assigned on the basis of the most current applications and can not be representative for pollutions which are arisen at the effective use of the product. The producer of the waste has to evaluate its process himself and has to grant the appropriate waste coding. See Decision 2001/118/EC. Removal contaminated packaging : Packing is to be used exclusively for the packing of this product. After use, empty and close the packing very carefully. In case of returned packing, the empty packing can be offered back to the supplier. SECTION 14. Transport information

UN Number

2582 14.2. UN proper shipping name BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 14. Transport information (continued) ADR/RID Name : UN 2582 Ferric chloride solution, 8, III, (E) ADN Name : UN 2582 Ferric chloride solution , 8, III IMDG Name : UN 2582 Ferric chloride solution, 8, III IATA Name : UN 2582 Ferric chloride solution , 8, III 14.3. Transport hazard classe(s) Class : 8 14.4. Packing group Packaging Group : III

Environmental hazards

Environmentally hazard : No Marine pollutant : No 14.6. Special precautions for user Danger number : 80 Hazard Label(s) : 8 EmS-N° : F-A , S-B 14.7. Transport in bulk according to Annex II of MARPOL 73/78 and the IBC Code Type ship : No data available. Pollution category : No data available. SECTION 15. Regulatory information 15.1. Safety, health and environmental regulations/legislation specific for the substance or mixture NFPA n° : 3-0-0 Relevant EU Rule(s) : Directive 98/24/EC of the Council of 7 April 1998 on the protection of the health and safety of workers from the risks related to chemical agents at work Decision 2001/118/EC of the Commission of 16 January 2001 amending Decision 2000/532/EC as regards the list of wastes Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006 Regulation (EU) No 453/2010 of 20 May 2010 amending Regulation (EC) No 1907/ 2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (Reach) National regulations - Germany : WGK : 1 - Netherlands : Water damaging : 9 Decontamination exertion : B 15.2. Chemical Safety Assessment A chemical safety assessment has been carried out for the components that make up this material. ...................................................................................12 Recommendations for minimising methane emis- sions include: Essentially the environment is only exposed to dan- „ All construction work must be as gas-tight ger if biogas escapes into the atmosphere or work- as possible. ing materials in the plant (e.g. digestion substrate, silage effluent, oils or fuels) enter nearby bodies of „ An automatic flare system should be installed. water. An accident of this type may be caused by This is particularly relevant regarding the CHP structural faults or operating errors. unit, as it is typically shut down for 5 to 10 % of the time for essential maintenance and repair Environmental hazards from biogas plants can be work; in this time biogas is produced continuous- divided into emissions into air and emissions into ly, and must not be allowed to escape unburned. soil and water. „ It should be ensured that the plant’s overpres- sure relief device is not released too often, the flare system should kick in before the overpres- Effects of an accident at a biogas plant sure relief device does. „Digestate storage tanks should have a gas-tight cover. „Methane emissions should be checked with appropriate measuring instruments, e.g. a gas camera or foam-forming agents. „The CHP unit should be optimised for the combustion of biogas. The methane emissions of CHP units can range from below 1% to over 2 % of methane production. Barth Emissions of ammonia from biogas plants should Josef also be minimised. Ammonia causes acidification photo: in soils, promotes eutrophication, can damage veg- etation and can have detrimental impacts on health In an accident at a biogas plant in Germany in June 2015, around 350,000 litres of slurry (in higher concentrations it is toxic; in groundwater, poured into nearby waters. Six tonnes of dead fish were recovered from the waters. converted to nitrite, it adversely affects metabo- lism). Measures to reduce ammonia are similar to Gaseous emissions those for methane. This means that gas emissions to One of the main environmental advantages of biogas the atmosphere should be avoided (especially from technology is the avoidance of uncontrolled green- the digestate storage tank). The techniques used for house gas emissions from the storage of organic field spreading of digestion products have a crucial materials. Furthermore, biogas substitutes fossil fu- influence on ammonia emissions. Where possible, els and synthetic mineral fertilisers, thus reducing digestion products should be worked into the soil carbon dioxide and methane emissions. However, quickly, and if at all feasible application should not methane – a particularly potent greenhouse gas – is take place when ambient temperatures are high (i.e. also produced through the anaerobic digestion pro- preferably on cool days and not around the middle cess at biogas plants. In order to preserve the cli- of the day). mate change benefits of biogas, unwanted methane emissions must be kept to a minimum. Various combustion products such as nitrogen ox- ides, sulphur dioxide, carbon monoxide and par- Analyses of biogas plants show that the digestate ticulates, among others, are produced during the storage tank is one of the main sources of methane combustion of biogas. Emissions of these products emissions, especially if it does not have a gas-tight should be regulated in the respective national regu- cover. The CHP unit also presents some hazard, lations. however in a lower degree. Other plant components are normally relatively gas-tight, but gas leakages at Emissions to soil and water connection parts between the gas storage and the The quantities of liquids processed and stored in digester and pre-digester pits could happen. biogas plants range from around a hundred to sev- 12 General requirements eral thousand cubic metres, individual tanks often „ Hazards associated with the use of additives and hold several thousand cubic metres. The contents of auxiliary materials with hazardous properties the tanks should not escape into the environment, (e.g. carcinogenic and reprotoxic mixtures of whether in normal operation or in the event of an trace elements). accident. Environmental impacts are most likely to arise from the organic load and nutrients. If a tank 4.4. Biological agents leaks, for example, large quantities of organically polluted liquids enter the environment. The high According to the International Labour Organisation organic load (high chemical oxygen load) is broken (Hurst & Kirby, 2004), biological agents are any down by microorganisms, thereby consuming oxy- microorganism, cell culture or human endopara- gen. The greatly reduced oxygen content can lead to site which may cause an infection, allergy, toxicity death of fish populations. If large quantities of sub- or otherwise create a hazard to human health. In strate enter the environment there is a considerable biogas plants, these biological agents can occur in risk of eutrophication of water bodies. feedstock, digestates and biogas condensates. The use of processing aids (refer to section on haz- The intake of biological agents through the respira- ardous substances) also brings with it the risk of tory tract, hand-to-mouth contact, skin/mucous environmental hazards. Mixtures of trace elements, membrane contact, cuts and stab injuries is relevant for example, if spilled into bodies of water, can be to the assessment of potential hazards. highly toxic for water organisms and have a long- term impact. The following are examples of hazards that may arise from biological agents during the production Table 3: Potential sources of ignition in biogas plants (TRBS 2153, 2009) In addition to the specific hazards outlined above, weather-related or other environmental sources of Source of ignition Examples danger may also arise, for example from flooding, earthquakes, storms, ice and/or snow, power outage, Hot surfaces >500 °C (turbochargers) heavy rainfall or frost. Site-related sources of danger such as the effect of neighbouring businesses or the Naked flames Fire, flames, embers traffic situation must also be taken into account. Mechanically generated sparks Friction, beating, grinding Environmental sources of danger such as these may result in interactions with other specific hazards. Switching operations, loose connection, Electrically generated sparks equalising currents 4.10. Hazards arising from inappropriate behaviour Exothermic reaction Spontaneous combustion of dusts Lightning strike missing lightning protection Potential hazards arising from inappropriate behav- iour must also be taken into account in the operation Electrostatic discharge Caused by missing potential equalization of a biogas plant. These include, for example: „ action by unauthorised persons „ dangers from personnel (operating errors, on-call service not working, deliberate failure to carry out fault rectification measures, sabotage, etc.) 16 General requirements 5. Hazard assessment In order to prevent accidents, hazards in biogas the design and selection of equipment and materi- plants must be systematically identified, assessed als and in the design of workplaces, working and and minimised. This is the purpose of a risk analysis. production processes and operating sequences, and the way in which these interact with each other. A tool to conduct this analysis is the risk matrix (see Table 4), which shows the likelihood of an undesir- This can also be laid down in national regulations. able event occurring (the risk) in relation to the con- As a rule, the operator is responsible for producing sequences of that event, in the form of a table. The the hazard assessment, or a person appointed by categories for the likelihood of an event occurring or the operator for this purpose. The hazard assess- taking effect are: rare, unlikely, possible, likely and ment must be updated prior to initial start-up of the almost certain. plant, following resumption of operation and after any changes are made that are relevant to safety. The categories are ‘reasonably estimated’ or statisti- cally verified in the course of the risk assessment. In order to assist operators in fulfilling their duties in The categories for the severity of the consequences this regard, in Germany it has proven worthwhile for are as follows: a qualified expert to check both the hazard assess- ment and the effectiveness of the protective meas- „ minor injuries or illnesses, e.g. bruising ures (see Figure 4). A hazard assessment must also „ moderately severe injuries or illnesses, e.g. be carried out before maintenance and repair work simple bone fractures is performed and before faults and malfunctions are „ severe injuries or illnesses, e.g. paraplegia rectified. „ possible death, disaster, e.g. severe injuries to numerous people The findings of the hazard assessment and the recurring updates must be documented, along Appropriate protective measures must be defined with a record of implementation of the protective and implemented on the basis of this assessment. measures. The findings obtained must be taken into account in Table 4: Risk analysis Potential Consequences Minor injuries or Injuries or illness Injuries or Injury or ill- Fatality discomfort. No requiring medical illness requi- ness resulting medical treatment treatment. Tem- ring hospital in permanent or measurable porary impairment. admission. impairment. physical effects Not Significant Minor Moderate Major Severe Expected to occur Almost Medium High Very High regularly under normal Certain circumstances Expected to occur at Likely Medium High Very High some point Likelihood May occur at some Possible Low Medium High Very High point Not likely to occur in Unlikely Low Medium High normal circumstances Could happen, but Rare Low Medium probably never will 17 General requirements Figure 4: Action at the various stages of hazard assessment 1. Establishment of working areas and tasks 7. Update hazard assessment determination Documentation 6. Evaluation of the effectivity assessment 5. Implementation 4. Establishment of the precautionary of precautionary measures As a general rule, the hierarchy determined by the ing sessions so that devices and equipment can be so-called TOP principle (see Figure 5) should be operated safely, but also for example making certain applied when instituting protective measures. This that filling does not take place when any individual means that first of all it is necessary to take techni- is within the danger area. In some cases, hazards are cal measures, such as enclosing rotating parts or unavoidable, despite technical and organisational ensuring that filling takes place in closed systems. protective measures. In such instances, personal Once all possible technical protective measures protective measures need to be put into practice to have been exhausted, organisational measures protect persons in the event of a hazard. This in- must be implemented, such as producing operat- cludes actions such as wearing a respirator (breath- ing instructions and holding instruction and brief- ing mask) if a release of biogas is unavoidable. Figure 5: Protective measures according to the TOP principle Sequence Technical Organisational Personal protective measures „Gas warning devices „Work instructions „Gloves „Mechanical ventilation „Briefing on procedures „Work clothing „Protective covers for „Emergency plans „Respiratory protection rotating parts „On-call service „Safety shoes „Enclosed metering station „Inspections and tests „Safety glasses for process additives „Requirements for lone working 18 General requirements 5.1. Hazard assessment for specific the hazard assessment (see section headed Hazard operating states assessment and see Figure 6) and must be applied when the work is carried out (TRGS 529, 2016). Normal operation for a plant is the state in which the plant is operated within its design parameters. It is not appropriate to consider start-up/shut-down or The necessary protective measures must be maintenance work on a continuously running biogas determined and documented as part of the plant as normal operation. Statistical evaluations of hazard assessment before the work is carried out. personal injuries at biogas plants reveal a significant- The documentation must also include written work ly high accident rate in connection with maintenance instructions, and in addition, in the case of work work and start-up or shut-down procedures. These with ignition hazards, must contain a permit-to- operating states should therefore be considered sepa- work system (see Annex 2 ‘Instruction record for rately, with their own specific operating instructions. subcontractors and employees for maintenance, installation and repair work’). 5.2. Start-up / commissioning It is always advisable to draw up a start-up plan be- During maintenance work on biogas plants, in addi- fore starting commissioning, and to follow it closely tion to the areas subject to explosion hazard desig- during the start-up phase. nated in the explosion protection document under normal operation (see section headed Explosion pro- Before the digester is filled for the first time, all work tection document) there may be further areas with a on it including the associated pipework must be hazardous explosive atmosphere (and depending on completed in order to prevent potential damage or the H2S content of the biogas, areas posing a health injury. Precise knowledge of the plant load requires hazard) for the duration of the work (for example the feedstock materials to be properly weighed. This when membrane roofs are opened in order to replace is highly important both for start-up operation and the agitator). for ongoing process control. In addition, regular chemical analysis of the feedstock materials and Appropriate protective measures include: in particular of the digestion mixture is a sensible „ Establishing and marking or cordoning off areas control measure for speedy start-up. However, if the where a risk of fire/explosion or a health hazard organic loading rate rises too fast during the phase is to be expected. of establishing the digestion biology, the process can quickly become overloaded; ultimately this can ex- „ Shutting down electrical and other tend the duration of start-up operation. Incomplete- non-explosion protected systems. ly filled tanks can lead to an uncontrolled escape of „ Removal of biogas from parts of the plant. biogas. During filling it is therefore important to take care that the filling level is sufficient to ensure that „ Selection of appropriate explosion-proof the substrate feeding equipment is fully immersed equipment and tools. in the liquid phase. „ Clearance measurement, i.e. the determination of the concentration of hazardous materials or It should also be noted that during start-up of the oxygen content using appropriate measuring plant an explosive gas mixture is temporarily present techniques in a certain area. The purpose of this because of the increase in the proportion of meth- is to classify the surrounding atmosphere as safe ane in the biogas (with a volume fraction of 6–22 % for employees or to initiate further protective biogas in air). measures. 5.3. Maintenance and repair work „ Use of appropriate personal protective equipment. Only persons who have the necessary specialist „ Ensuring adequate ventilation. knowledge and experience for the relevant work and of whom it can be expected that they will perform „ Appointment of a supervisor. their task reliably should be allowed to maintain and repair biogas plants. The protective measures Employees engaged in activities in the vicinity of required for the maintenance and repair of biogas maintenance and repair work must be notified of plants must be defined by the client on the basis of the timing, location and nature of the planned work 19 General requirements and of the restrictions and hazards that could arise „ ensure adequate communication between as a result and therefore the precautions and care operating staff and maintenance and repair that they need to take. Maintenance and repair work personnel; must always be performed by employees who are „ secure the working area during the maintenance capable for the work and have been assigned to it by and repair work; the plant operator or owner. They must have the nec- essary specialist knowledge to carry out the main- „ prevent unauthorised parties from entering the tenance or repair order by virtue of their vocational working area, if this is deemed necessary ac- education or professional training. cording to the hazard assessment; „ provide safe access points for maintenance and In all maintenance and repair work it is essential to repair personnel; use tools and other work equipment that is suited to the intended purpose and the conditions at the „ avoid hazards from moving or elevated work workplace when used appropriately. equipment or parts of the equipment and from hazardous energy or materials; To summarise, in specific exceptional operating „ ensure that devices are disconnected from en- states the operator must ergy sources. Remaining mechanical and electri- „ define the responsibilities for implementing the cal energy (e.g. current leak) should be removed requisite protective measures; safely. These devices must be marked or labelled appropriately; Figure 6: Flow diagram for maintenance and testing (TRBS 1112-1, 2010) Task Have workflow Are the determined performance of work and measures been yes1 measures sufficiently yes Procedure in accordance described? effective? with agreed and documented provisions no „Obtain additional information2 „Identify hazards yes „Evaluate hazards New hazards? „Determine and document no measures Interrupt work! Notify the person in charge no Can testing be carried out safely? yes Testing To 1: in routine activities this is usually the case if activity is always the same: „ A hazard assessment already exists no Has a safe and reliable „ The hazardous situation is reproducible Rectify all operating state been „ The measures (work equipment, action etc.) discrepancies discovered re-established? have been defined yes To 2: „ Manufacturer’s information „ Task assignment End „ Fault description 20 General requirements „ stipulate safe working practices for working con- Figure 7: Sequence of explosion protection measures ditions that deviate from the normal state; „ provide all necessary warning symbols and haz- Primary Prevention of formation of explosive atmospheres ard warning signs regarding maintenance and Ex-Protection „Substitution, inert atmosphere, limitation of concentration, intensive ventalition repair work on the work equipment; „ ensure that only suitable devices and tools are used, and appropriate personal protective equip- ment; Secondary Prevention of ignition Ex-Protection „Ex- Zoning, preventing sources of ignition, „ comply with relevant protective measures if a organisational measures hazardous explosive atmosphere occurs or is formed; „ use systems for approving certain works. Tertiary Reduction of explosion consequences If the technical protective measures applied dur- „Personal Protective Equipment (PPE), explosion ing normal operation are partly or entirely taken Ex-Protection supression, explosion pressure resistance out of service during maintenance or repair work „Evacuation or enough distance on work equipment, or if such work must be per- formed in the presence of an energy hazard, the safety of the employees for the duration of this work must be ensured by taking other suitable measures. The workflow for maintenance measures is shown „ A hazardous explosive atmosphere may be formed in Figure 6. around outlet nozzles. Ignition sources must be avoided (see section headed Explosion and fire 5.4. Shut-down / decommissioning hazards). „ Before entering the digester and throughout the The removal of a biogas plant from service is a spe- time spent in the tank it must be ensured that any cial operating state that requires particular meas- risk of asphyxiation, poisoning, fire or explosion ures. The Ex zones classified in the explosion pro- is safely prevented through adequate ventilation tection document (see section headed Explosion and that sufficient air is available to breathe. Any protection document) take account of this operating operational equipment such as pumps or agita- state to only a limited extent. tors must be safely secured to prevent them from being switched on. These specific hazards are therefore considered separately in a set of work instructions. 5.5. Explosion protection document „ The loading of substrate in the digesters is stopped, while removal continues. The quantity The explosion protection document is part of the of substrate removed must not exceed the volume hazard assessment, involving the identification and of gas generated in order to prevent the formation evaluation of explosion hazards. In particular it is of a hazardous explosive atmosphere. necessary to determine where a hazardous explosive atmosphere (or potentially explosive atmosphere – „ If the quantity of substrate removed is liable to PEA) can be expected and what potential ignition exceed the volume of gas generated, the digestion sources could cause ignition (see section headed tank is shut off from the gas collection system and Explosion and fire hazards). As a general principle a connection to the atmosphere is established, for the first step is to implement primary structural example by emptying the liquid seal of the over measures that prevent hazardous explosive atmos- and under pressure unit. A hazardous explosive pheres from arising. Secondary, technical measures atmosphere may now be formed in the digester as must then be implemented if a hazardous explosive a result of the entry of air. Ignition sources (see atmosphere is unavoidable; they are aimed at avoid- section headed Explosion and fire hazards) must ing the creation of ignition sources. The final choice be avoided. of measure should be tertiary or organisational „ The digester must be shut off from the gas collec- measures, which are aimed at reducing the poten- tion system in order to prevent gas backflow. tial consequences of an explosion (see figure 7). 21 General requirements areas can be divided into zones accord- The national guidelines on the classification of areas ing to the frequency and duration of the occurrence as Ex zones must be observed. Examples of zoning of hazardous explosive atmospheres (see Figure 8). and the associated protective measures are given in the second part of this document. Figure 8: Classification of Ex zones Zone 0 or zone 20 An area in which a hazardous explosive atmosphere consisting of a mixture of Danger !!! air and combustible gases, vapours or mists is present continuously or for long periods or frequently. Zone 1 or zone 21 Danger !! An area in which a hazardous explosive atmosphere consisting of a mixture of air and combustible gases, vapours or mists is likely to occur occasionally in normal operation. Danger ! Zone 2 or zone 22 An area in which a hazardous explosive atmosphere consisting of a mixture of air and combustible gases, vapours or mists does not normally occur but, if it does, does so only rarely and for a short period. Figure 9: Description of an ATEX label European 2 G Ex d IIC T4 Gb for Gas II 2 G Ex d IIC T4 Gb Conformity Group „G“ „D“ for Dusts Type Code* European Code* Mark Explosion Equipment Conformity Group „G“ „D“ for Dusts Type for Gas Code* Protec>on Equipment Code* Category Equipment Protec>on* Protec>on Gas Group* Temp Mark Protec>on Explosion * ATEX/IECex II Explosion Hazardous Equipment Mark Equipment * ATEX/IECex Level* Mark Level*

Further information

This safety data sheet has been drawn up in accordance with Regulation (EU) No 453/2010. This safety data sheet is exclusively made for industrial/professional use. * Has changed compared to previous revision. BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 SECTION 16. Other information (continued) * Changes : Section 1 , Section 2 , Section 3 , Section 5 , Section 7 , Section 8 , Section 9 , Section 12 , Section 14 , Section 15 , Section 16 . Sources of used key data : See also on the webaddress: http://apps.echa.europa.eu/registered/registered-sub.aspx#search The information contained herein is based on the present state of our knowledge ( Producer(s) , Chemical cards , ...). The ATEX Guidelines can be consulted on the European Union Law website and are available in English, Spanish, French and Portuguese. 22 General requirements 5.6. Requirements for work equipment In zone 1 only equipment that is approved for zone in hazardous areas 0 or 1 and is correspondingly marked may be used. Only equipment and protective systems of equip- To enable work equipment to be used in hazardous ment group II category 1 G or 2 G according to Annex areas (potentially explosive atmospheres, PEA), it 1 of ATEX may be used. must be approved for use in the respective Ex zone. European Directive 2014/34/EU (ATEX, 2014) In zone 2 only equipment that is approved for zone 0, (ATEX Product Directive, referred to in the following 1 or 2 and is correspondingly marked may be used. simply as ATEX), has become established as the ba- Only equipment and protective systems of equip- sis for the use of equipment and protective systems ment group II category 1 G, 2 G or 3 G according to in Ex zones (see Figure 9). Annex 1 of ATEX may be used. According to this directive, only equipment that is Details of the zoning must be recorded in an Ex approved for zone 0 and is correspondingly marked zone plan (see Figure 10). This must be regularly may be used in zone 0. Only equipment and protec- checked to ensure that it is up-to-date, and adapted tive systems of equipment group II category 1 G ac- as necessary. cording to Annex 1 of ATEX may be used. ➀ Overpressure and underpressure protection ➁ Wall duct for submersible mixer ➂ Outlet of the membrane gas storage tank Figure 10: Example of a Ex-zone plan for a biogas ➃ Blower of the membrane gas storage tank plant (red = zone 1, orange = zone 2) ➄ Space in between the membranes of the gas storage gMBh inreetec soUrce: 23 General requirements 6. Fire protection concept Biogas plants have various fire loads depending on „ Electrical installations: Electrical installations the plant concept, plant size, substrate input, the must comply with recognised rules (applicable operating and work equipment used and the mate- in each specific country) and must be regularly rials used. Structural, technical and organisational checked by an authorised electrician. The opera- fire protection measures must be included from the tor should regularly carry out visual checks for design and planning of the plant. In particular, na- rodent damage and signs of scorching in order to tional guidelines must be taken into account regard- minimise the risk of fires starting. ing fire protection. „ Safety distances: The purpose of safety dis- tances is to reduce mutual influence in the 6.1. Structural fire protection event of damage occurring and to prevent fire from spreading and protect the gas storage tank. The following structural fire protection measures To this end it is necessary to provide for safety have proved their worth in practice: distances of at least 6 m in a horizontal direction „ Digester: If thermal insulation is necessary for between gas storage tanks and adjacent non-bi- digesters, it should be at least normally inflam- ogas-related installations, facilities and buildings mable. Within an area of 1 m around openings (with a height below 7.5 m) or to transport routes. where gas is released during normal operation, it Z If one building is higher than 7.5 m, gas must be made of at least low-flammable material. storage or building not belonging to the plant, the formula for the distance a is: Further information on the thermal a = 0.4 x + 3 m. H1 insulation requirements for Z If there are two buildings higher than 7.5 m, construction products and building gas storage or building not belonging to the elements can be found in the plant, the formula for the distance a is: standard DIN EN 13501-1. a = 0.4 x H1 + 0.4 x H2. „ CHP unit installation rooms and installation in Safety distances of at least 6 m must be provided buildings not belonging to the plant: Walls, sup- within a biogas plant between the gas storage tank ports and ceilings above and below installation and installation rooms for internal combustion en- rooms must be at least fire resistant (e.g. F 90 in gines. In above-ground installations the safety dis- Germany) and be made of non-flammable build- tance is measured from the vertical projection of the ing materials. No cladding or insulation made of edge of the storage tank (see Figure 11). flammable materials may be used for walls, ceil- ings or supports. Doors in fire-resistant walls must Figure 11: Safety distances between gas storages be at least fire-retardant and self-closing; this and adjacent builidings does not apply to doors leading to the open air. Ventilation ducts and other pipework or cables should only be run through walls and ceilings if the ducts, pipes or cables themselves are incapable of spreading fire or precautions have been taken to prevent fire spreading (e.g. cable penetration seal with general approval from the construction supervision authority, or fire dampers suited for the intended purpose). Exhaust gas lines (stacks) and the associated penetrations must comply with the respective country-specific requirements. Sufficient clearance from flammable materials should be ensured. Spaces in the penetrations must be filled with non-flammable, dimension- ally stable materials. This condition is met if suit- able materials are used which have the same fire- resistance rating as the components being sealed. 24 General requirements Danger to persons and the risk of fire inside or out- fire brigade should use appropriate personal protec- side the biogas plant through thermal radiation or tive equipment, a gas detector (CH4, CO2, H2S, etc.) convection must be precluded by appropriate po- must be kept ready for use, attention must be paid to sitioning of the emergency flare. In this regard con- the wind direction when approaching the site, a safe sideration must be given to buildings, plant compo- distance must be maintained, the formation of igni- nents, transport routes and public areas. tion sparks must be avoided (e.g. electrical switch- „ Protective wall: The safety distance can be re- es!), and the operator on site must be consulted. duced through sufficient covering with earth or an adequately dimensioned protective wall or fire As far as possible, all necessary safety and health insulation (i.e. firewall). Doors in protective walls protection signage should be considered during the must be fireresistant and self-closing. A protective planning of workplaces (for example when drawing wall can also be an appropriately designed building up escape and rescue plans). It is also important to wall without openings. The height and width of the appoint first aiders. Extinguishing agents (fire extin- protective wall must comply with the requirements guishers, supply of fire-fighting water) must be made of the respective national guidelines. available according to the fire loads, in consultation with the fire brigade. bustible materials stored in quantities of over 200 ! 6.2. Organisational fire protection TIP The latest rescue and fire safety symbols Within the safety distances there should not be com- are specified in ISO 7010. kg without additional protective measures, and there should neither be buildings that do not belong to the biogas plant nor public roads or paths. Additional protective measures may include fire prevention measures, fire protection measures and fire-fighting measures (see section on protective walls, for exam- ple). Besides this, the following conditions apply: „ transport routes essential for operation of the plant are permissible; „ no vehicles may be parked within the safety distance area; „ machinery and activities that can cause danger to the gas storage tank (e.g. welding or cutting) are not permitted without additional protective measures; „ no gas flares may be operated; „ fires, naked flames and smoking are prohibited. Employees and external companies must be in- structed periodically, as and when appropriate, on measures to be taken in the event of operational faults, accidents and emergencies and how to pre- vent these. It has proven worthwhile to discuss and coordinate fire protection considerations at the plant with the responsible fire brigade prior to commissioning and ortakcioglU at regular intervals. Close coordination with the _oktay leaders of the local fire brigade units is essential in advance of tactical deployment of the fire brigade fotolia in the event of fire or for other forms of technical assistance. It is recommended to hold an exercise photo: in order to ensure that correct action is taken in the event of a deployment. In case of deployment, the 25 General requirements 7. Protective measures With regard to occupational health and safety, the out and repeated in accordance with the findings of general rule is to establish protective measures ac- the hazard assessment. cording to the TOP principle (see section Hazard as- Examples of instruction and briefing: sessment). „ Safety and health at work „ Work in areas where there is an explosion hazard The plant operator must ensure the safe handling of work equipment and the safe operation of plants and „ Internal company instructions plant components with the aid of technical protec- „ Hazardous substances present or arising at the tive measures. The technical protective measures workplace for specific plant components are explained in the Z in particular hygiene regulations second part of this brochure. Z information about measures to be taken to prevent exposure 7.1. Organisational protective measures Z information about wearing and using personal Organisational structure protective equipment and protective clothing The operator should design and document the plant’s organisational structure in such a way that Before commencing work/activities, employees all activities and tasks can be safely performed and must receive initial instruction and then at regular monitored at all times. intervals, at least once a year. A written record of the The following arrangements should be made, at the instruction should be kept. very minimum: „ responsibilities (e.g. for checking the operat- Dangerous tasks must be performed in accordance ing log, carrying out instruction/briefing and with the written instructions of the employer or the performing the hazard assessment; the employer person responsible; a permit-to-work system must can delegate tasks to an employee) be used when dangerous activities are to be car- ried out or activities that can become dangerous in „ deputisation arrangements combination with other work. Examples: work inside „ on-call service: if the plant is operated by several tanks and in tight spaces, work entailing an ignition people in shifts, handover at the change of shifts hazard (welding, flame cutting, drilling etc.), work must be ensured and any particular occurrences on roofs, work in hazardous areas. must be documented in writing (e.g. in the operation diary) Appropriate supervision must be ensured during the „ if necessary, assignment of the right to issue presence of employees in hazardous areas. The Ger- instructions man Biogas Association provides an example of a permit-to-work system with the Instruction record Operating instructions for subcontractors and employees for maintenance, A thorough briefing (presentation of the operating installation and repair work (see Annex 2). instructions) by the plant manufacturer is essential prior to commissioning and if any modifications are Employees must receive instruction prior to com- made. Evidence of the content covered should be mencing work on or with new work equipment, new given in writing. In addition, the operating personnel procedures/changed procedures, new hazardous of the biogas plant should take part in further train- substances or new responsibilities. ing and continuing professional development, and the certificates should be kept. If personnel from The following should be documented: external companies work at the biogas plant, their „ Content of the briefing professional suitability must be established and ver- ified as necessary. A suitable briefing form should be „ Briefing of external personnel used to ensure that external personnel are briefed on „ Briefings and instruction held operational hazards. Instruction and briefing Requirements for lone working Instruction and briefing by the plant operator on the As part of the hazard assessment it is necessary to safe handling of work equipment should be carried examine which activities can be performed by work- 26 General requirements ing alone and to document these. If it is established „ permanently staffed camera surveillance, in the course of the hazard assessment that a par- „ use of a personal emergency signalling device ticular activity cannot be performed alone, this ac- with automatic alarm functions, tivity should always be performed by at least two „ reporting intervals with visual or voice contact, employees. As a rule, the following activities cannot be performed alone: „ working within visual range, 1. work inside tanks and in tight spaces (a person „ supervision through inspection tours, must be assigned to stand guard for safety rea- „ provision of a landline phone/mobile phone sons when work is carried out inside tanks or in to make emergency calls. tight spaces, if there are no doors through which the worker can leave); If these protective measures might themselves be or include sources of ignition, their suitability must be 2. work in areas where additional explosion hazards examined before they are used in hazardous areas may arise in the course of maintenance or repair (TRGS 529, 2016). work because of the local conditions, the equip- ment installed in those areas or the substances, Organisational protective measures also include preparations or impurities contained in them or regular maintenance of the plant, systems and com- introduced into them (TRBS 1112-1, 2010). ponents. In order to be able to guarantee safe opera- Where lone working is permissible, appropriate tech- tion, it is essential to draw up a maintenance plan nical and organisational protective measures must with specific details of the plant components to be be determined by means of which effective first aid maintained and to specify maintenance intervals. can be ensured if the need arises. Examples of suit- Maintenance also includes functional testing of the able protective measures include the following: individual components and completion of the rel- evant documentary evidence. Maintenance work with protective measures in a digester gMBh polygonVatro photo: 27 General requirements 7.2. Personal protective measures In addition to technical and organisational protective measures, personal protective measures must also be planned for specific aspects of plant operation. The choice of measures to be used depends on the hazard assessment (see Table 5). Table 5: Hazards and possible protective measures Examples Personal protective equipment jet filius 104 filius 204 filius R04 filius 106 filius 206 patruus 50 patruus 64 patruus 100 patruus 190 patruus 250 patruus 370 agenitor 206 agenitor 306 agenitor 406 agenitor 408 agenitor 212 agenitor 312 avus 500a avus avus 500b avus 500c avus 800a avus 800b avus 800c avus 1000a avus 1000b avus 1000c avus 1500b avus 1500c avus 2000c avus 2000a avus 3000a 500plus RELEASE CONDITIONS Absolute upstream temperature of release T K 293 Absolute ambient temperature 293 Ta 293 K 293 Upstream pressure in bar gauge 293 P 293 barg 293 0.07 293 0.07 293 0.07 293 0.07 293 0.07 293 0.07 293 0.07 293 0.07 293 0.07 293 0.07 293 Absolute upstream pressure 0.07 P 0.07 Pa 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 107000 0.15 Pressure difference across the leak opening 107000 115000 ΔP Pa 115000 5675 115000 5675 115000 5675 115000 5675 115000 5675 115000 5675 115000 5675 115000 5675 115000 5675 115000 5675 115000 5675 Cross sectional area of leak path 5675 13675 S mm2 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 Factor of Safety applied to LEL. 0.25 k 0.25 - 0.25 0.5 0.25 0.5 for primary release; 0.25 for secondary. 0.5 PHYSICAL PROPERTIES 0.5 Relative molecular mass M kg/kmol 16 Lower explosive limit 16 E% 16 % 16 4.4 16 4.4 16 4.4 16 4.4 16 4.4 16 4.4 16 4.4 16 4.4 16 4.4 16 4.4 16 4.4 Specific heat of gas at constant pressure 4.4 cp 4.4 J/kg/K 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 GAS RELEASES 2220 Is release sonic (choked) or subsonic (unchoked)? - non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked Gas release rate Wg kg/s 2.16E-05 GAS/VAPOUR RELEASE RATE USED FOR ZONE EXTENT 2.16E-05 3.34E-05 Release rate used in further calculations Wg kg/s 2.16E-05 3.34E-05 Volumetric gas flow = RTWg/(MP) IEC 60079-10-1 section B.7.2.3.3 3.34E-05 Qg 3.34E-05 m3/s 3.34E-05 3.25E-05 3.34E-05 3.25E-05 3.34E-05 3.25E-05 3.34E-05 3.25E-05 3.34E-05 3.25E-05 3.34E-05 3.25E-05 VENTILATION 3.25E-05 5.02E-05 Indoors or outdoors location Indoors Type of ventilation Indoors ventilation Exhaust Indoors ventilation Exhaust Indoors ventilation Exhaust Indoors ventilation Exhaust Indoors ventilation Exhaust Indoors ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust Room volume ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust Vo ventilation Exhaust m3 ventilation Exhaust 41 ventilation Exhaust 41 58.5 81 Air flow rate from room 81 108 Qa 108 m3/s 108 1.95 108 1.62 108 1.02 108 1.62 108 1.90 108 1.95 108 1.31 108 1.62 135 2.11 333 2.63 333 3.90 2.36 2.60 2.58 Air change rate 3.72 3.98 4.58 5.71 5.29 6.87 C 6.49 h-1 9.00 171.6 9.59 142.2 8.72 89.3 11.49 142.2 12.82 166.8 13.09 171.6 16.03 80.8 16.80 99.7 21.52 130.0 19.44 161.9 25.00 Ventilation velocity 240.0 104.8 115.4 114.5 165.5 176.7 Vo/AR 203.6 m/s 190.2 0.24 176.5 0.20 229.0 0.13 216.3 0.20 300.2 0.24 319.5 0.24 290.7 0.16 382.9 0.20 427.2 0.26 436.4 0.33 Mixing efficiency. Good=1, bad=5 534.2 0.49 559.9 0.29 573.9 0.32 210.2 0.32 270.3 0.47 0.50 f 0.57 0.71 5 0.66 5 0.86 5 0.81 5 1.13 5 1.20 5 1.09 5 1.44 5 1.60 5 1.64 5 2.00 5 2.10 5 2.69 5 2.43 5 3.13 Ventilation availability 5 Good 5 Good 5 Good 5 Good 5 Good 5 Good 5 Good 5 Good 5 Good 5 Good 5 Good DEGREE OF DILUTION Good Critical concentration (25% or 50% of LEL) Xcrit vol/vol 0.022 Concentration of vapour in room exhaust 0.022 XLEL 0.022 %LEL 0.022 0.04% 0.022 0.05% 0.022 0.07% 0.022 0.05% 0.022 0.04% 0.022 0.04% 0.022 0.06% 0.022 0.05% 0.022 0.03% 0.022 0.03% 0.022 0.02% 0.022 0.03% 0.022 0.03% 0.022 0.03% 0.022 Release characteristic IEC 60079-10-1 Equation C.1 0.02% Wg/(ρgkE) 0.02% m3/s 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.00% 7.4E-04 1.1E-03 Dilution 1.1E-03 Degree of dilution IEC 60079-10-1 Figure C.1 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution ZONE EXTENT high Dilution high Dilution high Dilution high Dilution high Zone extent IEC 60079-10-1 Figure D.1 NE Copyright  CSA Group Testing UK Limited. Page 20 of 23 70066329/03 Natural gas AREA CLASSIFICATION CALCULATIONS Calculation: 33 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Flammable material: 19 20 21 22 23 24 25 natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas natural gas Source of release: pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak Type of release pipework leak pipework leak pipework leak pipework leak Secondary Physical form of release Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gbox 20 patruus 100 patruus 140 patruus 200 patruus 240 patruus 250 patruuus agenitor 206 agenitor 306 agenitor 406 agenitor 408 avus 400 avus 500a avus avus 500b avus 500c avus 800a 400 avus 800b avus 800c avus 1000a avus 1000b avus 1000c avus 1500b avus 1500c avus 2000c 500plus RELEASE CONDITIONS Absolute upstream temperature of release T K 293 Absolute ambient temperature 293 Ta 293 K 293 Upstream pressure in bar gauge 293 P 293 barg 293 0.1 293 0.07 293 0.07 293 0.07 0.15 Absolute upstream pressure 0.15 P 0.15 Pa 0.15 110000 0.15 107000 0.15 107000 0.15 107000 115000 Pressure difference across the leak opening 115000 ΔP 115000 Pa 115000 8675 115000 5675 115000 5675 115000 5675 Cross sectional area of leak path 13675 S mm2 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 13675 0.25 Factor of Safety applied to LEL. 0.25 k 0.25 - 0.25 0.5 for primary release; 0.25 for secondary. 0.5 PHYSICAL PROPERTIES 0.5 Relative molecular mass M kg/kmol 16 Lower explosive limit 16 E% 16 % 16 4.4 16 4.4 16 4.4 16 4.4 Specific heat of gas at constant pressure 4.4 cp J/kg/K 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 4.4 2220 GAS RELEASES 2220 Is release sonic (choked) or subsonic (unchoked)? - non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked non-choked Gas release rate Wg kg/s 2.67E-05 2.16E-05 3.34E-05 GAS/VAPOUR RELEASE RATE USED FOR ZONE EXTENT 3.34E-05 Release rate used in further calculations Wg kg/s 2.67E-05 2.16E-05 3.34E-05 Volumetric gas flow = RTWg/(MP) IEC 60079-10-1 section B.7.2.3.3 3.34E-05 Qg m3/s 4.01E-05 3.25E-05 5.02E-05 VENTILATION 5.02E-05 Indoors or outdoors location Indoors Type of ventilation Indoors ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust ventilation Room volume Exhaust ventilation Exhaust ventilation Exhaust ventilation Exhaust Vo m3 41 58.5 81 108 Air flow rate from room 108 Qa 108 m3/s 108 0.10 108 1.64 108 1.91 135 2.21 2.84 2.67 4.37 2.38 2.63 2.65 3.78 2.72 3.75 5.42 Air change rate 4.87 3.82 6.01 6.76 4.94 7.36 C 8.85 h-1 7.14 8.5 10.74 100.8 9.37 117.7 11.96 136.2 174.7 164.5 194.1 105.9 117.0 117.7 167.9 Ventilation velocity 121.0 124.9 180.6 162.4 127.2 Vo/AR 200.4 m/s 225.2 0.01 164.6 0.20 245.2 0.24 295.1 0.28 238.1 0.35 358.1 0.33 312.4 0.55 318.9 0.30 0.33 0.47 Mixing efficiency. Good=1, bad=5 0.34 0.47 0.68 0.61 0.48 0.75 f 0.84 0.62 5 0.92 5 1.11 5 0.89 5 1.34 5 1.17 5 1.49 5 Ventilation availability 5 Good 5 Good 5 Good 5 Good DEGREE OF DILUTION Good Critical concentration (25% or 50% of LEL) Xcrit vol/vol 0.022 Concentration of vapour in room exhaust 0.022 XLEL %LEL 0.022 0.94% 0.022 0.05% 0.022 0.04% 0.022 0.03% 0.022 0.03% 0.022 0.03% 0.022 0.02% 0.022 0.03% 0.02% 0.04% 0.03% 0.02% Release characteristic IEC 60079-10-1 Equation C.1 0.02% 0.03% 0.02% Wg/(ρgkE) 0.01% m3/s 0.02% 9.1E-04 0.01% 7.4E-04 0.01% 7.4E-04 0.01% 7.4E-04 1.1E-03 Degree of dilution IEC 60079-10-1 Figure C.1 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution 1.1E-03 Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high Dilution high ZONE EXTENT high Zone extent IEC 60079-10-1 Figure D.1 NE Copyright  CSA Group Testing UK Limited. Page 21 of 23 70066329/03 NATURAL GAS OUTDOOR AND INDOOR RELEASES AREA CLASSIFICATION CALCULATIONS Calculation: 1 2 Flammable material: natural gas Source of release: pipework leak pipework leak Type of release Secondary Physical form of release Gas/vapour jet Gas/vapour jet avus 2000c Outdoor gas Indoor gas leak. leak RELEASE CONDITIONS Absolute upstream temperature of release T K 293 Absolute ambient temperature Ta K 293 Upstream pressure in bar gauge P barg 0.15 Absolute upstream pressure P Pa 115000 Pressure difference across the leak opening ΔP Pa 13675 Cross sectional area of leak path S mm2 0.25 Factor of Safety applied to LEL. k - 0.5 0.5 for primary release; 0.25 for secondary. PHYSICAL PROPERTIES Relative molecular mass M kg/kmol 16 Lower explosive limit E% % 4.4 Specific heat of gas at constant pressure cp J/kg/K 2220 GAS RELEASES Is release sonic (choked) or subsonic (unchoked)? - non-choked Gas release rate Wg kg/s 3.34E-05 GAS/VAPOUR RELEASE RATE USED FOR ZONE EXTENT Release rate used in further calculations Wg kg/s 3.34E-05 Volumetric gas flow = RTWg/(MP) IEC 60079-10-1 section B.7.2.3.3 Qg m3/s 5.02E-05 VENTILATION Indoors or outdoors location Outdoors Indoors Type of ventilation Natural outdoor indoor Room volume Vo m3 0 1000 Air flow rate from room Qa m3/s 0.00 0.010 Air change rate C h-1 0.0 Ventilation velocity Vo/AR m/s 0.50 Mixing efficiency. Good=1, bad=5 f 1 Ventilation availability Good DEGREE OF DILUTION Critical concentration (25% or 50% of LEL) Xcrit % 2.2% Concentration of vapour in room exhaust XLEL %LEL N/A 50.2% Release characteristic IEC 60079-10-1 Equation C.1 Wg/(ρgkE) m3/s 1.1E-03 Degree of dilution IEC 60079-10-1 Figure C.1 Dilution high Dilution high ZONE EXTENT Zone extent IEC 60079-10-1 Figure D.1 NE Copyright  CSA Group Testing UK Limited. Page 22 of 23 70066329/03 Appendix 4 References The following publications were referenced in compiling this report: - 1 ATEX Directive 1999/92/EC: Minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres. 2 Dangerous Substances Explosive Atmospheres Regulations:2002 (‘DSEAR’). 3 IEC 60079-10-1 2015 - Explosive atmospheres - Part 10-1 Classification of areas – Explosive gas atmospheres 4 Analysis Of Ethylene Glycol-Based Engine Coolant As A Vehicle Fire Fuel. Hull, Robertson, Mullen, Stradling and Sidwell. International Symposium on Fire Investigation Science and Technology, 2008. 5 Research report RR630: Area classification for secondary grade releases from low pressure natural gas systems, HSL, 2008 6 Classification of Hazardous Locations, Cox, Lees & Ang, 1990, Appendix 7, A7.3. 7 EN 1127-1:2007 - Explosive atmospheres - Explosion prevention and protection, Part 1. Basic concepts and methodology. Copyright  CSA Group Testing UK Limited. Page 23 of 23 70066329/03 APPENDICES APPENDIX I – 2G DOCUMENT: “SHUTDOWN-MATRIX” 31.01.2019 Shutdown and breaker Supply circuit 60sec instantly drives Power Stop stops Roomfan 230V Gasblower Auxiliary 24V Generator approx. Reaction CHP in CHP Emergency-Stop X Gasalarm 40% UFL 100% X Emergency-Stop & 100% X Gasalarm 40% UFL Maintanance Switch X Gas pressure min. X Safety temperature limiter X Gas pre-alarm 20%UFL 100% X Smoke alarm X ^ Lights Airconditioning, Sockets, Note: The shutdown matrix only considers the planning of a CHP-plant . If this is sufficient must be checked by the operator. APPENDICES APPENDIX J – FLOGAS DOCUMENT: DETERMINATION OF HAZARDOUS CLASSIFICATION ZONES, METHODOLOGY USED TO DETERMINE DIMENSIONS OF THE ZONED AND PROTECTED AREAS OF: 6 X 2 TONNE LPG VESSELS FOR PUMPED LIQUID PROPANE SUPPLY”, ISSUE 1, DATED JULY 2017” 6 x 2 tonne Pumped Liquid Propane Issue 1 –July 2017 DETERMINATION OF HAZARDOUS CLASSIFICATION ZONES METHODOLOGY USED TO DETERMINED DIMENSIONS OF THE ZONED AND PROTECTED AREAS OF:- 6 x 2 tonne LPG Vessels For Pumped Liquid Propane Supply 1 of 6 6 x 2 tonne Pumped Liquid Propane Issue 1 –July 2017 1. INTRODUCTION AND SCOPE This document outlines the method by which 6 x 2 tonne LPG vessels for pumped liquid propane supply installations have been assessed for the purposes of identifying the zoned areas in accordance with the DSEAR Regulations (Dangerous Substances and Explosive Atmosphere Regulations) and using the approach detailed in IP Area Classification Code Part 15, UKLPG and AEGPL (European LP Gas Association) guidance. It also identifies ‘Protected Areas’ in compliance with the guidance contained within the relevant UKLPG Codes of Practice. The information contained in this document should be used in association with the relevant drawings when undertaking a site specific DSEAR risk assessment. 2. INTRODUCTION. 2.1 Designations for LPG (Commercial Propane) Fluid Category is A (Table 1.2) Fluid Class is 0 (Table A1) 2.2 Ventilation Ventilation in all parts of this installation have been classed as open (6.2.). 2.3 Release Rates of LPG. There are no continuous releases of LPG from these installations. Consequently, any release (as defined in 1.6.4.) has been defined as either Primary or Secondary. 2.4 Probability of Ignition. All permanent sources of ignition on the site should have been identified as outside of the zoned/protected areas, installed electrical equipment has been checked to ensure that it is correctly rated for the zone or area in which it is installed and an ignition probability established. There is an allowable maximum release frequency of 1.0Eˉ2 to achieve the required maximum ignition release level of 1.0Eˉ5. 2 of 6 6 x 2 tonne Pumped Liquid Propane Issue 1 –July 2017 3 REFERENCES All references numbers refer to sections or tables in the IP Area Classification Code Part 15 2nd Edition unless stated otherwise. On the hazard radii table C9 some of the data used has been extrapolated by the use of derived graphs. 4 DEFINITIONS 4.1 Off loading Gas being pumped from a road tanker into the bulk storage vessel(s) 4.2 Frequently Used Valves operated weekly or more often, during normal working. 4.3 Rarely Used Valves that are not ‘Frequently Used’ 4.4 Zone 1 Area (As applied to these installations) A place where an explosive atmosphere consisting of a mixture of Propane in Air is occasionally likely to occur in normal operations. In the IP Code Part 15 this usually equates to a Primary Release. 4.5 Zone 1 Area (As applied to these installations) (Temporary) A place where an explosive atmosphere consisting of a mixture of Propane in Air is occasionally likely to occur during storage vessel filling and cylinder refuelling operations. In the IP Code Part 15 this usually equates to a Primary Release. 4.6 Zone 2 Area (As applied to these installations) A place where an explosive atmosphere consisting of a mixture of Propane in Air is not likely to occur in normal operations but if it does occur, will persist for a short period only. In the IP Code Part 15 this usually equates to a Secondary Release. 3 of 6 6 x 2 tonne Pumped Liquid Propane Issue 1 –July 2017 4.7 Protected Area This is an area which is not classified as being either Zone 1 or 2 by the calculations in IP Area

R-phrase(s)

R22 - Harmful if swallowed. R34 - Causes burns. R37 - Irritating to respiratory system. R38 - Irritating to skin. R41 - Risk of serious damage to eyes.

Supplemental label elements

H290 - May be corrosive to metals. H302 - Harmful if swallowed. H315 - Causes skin irritation. H318 - Causes serious eye damage. * List of abbrevations and acronyms : ADN (Accord européen relatif au transport international des marchandises Dangereuses par voie de Navigation interieur) : European agreement concerning the international carriage of dangerous goods by inland waterways ADR (Accord européen relatif au transport international des marchandises Dangereuses par Route) : European agreement concerning the international carriage of dangerous goods by road DNEL (Derived No Effect Level) : an estimated safe exposure level EC50 : median Effective Concentration EmS (Emergency Schedule) : the first code refers to the relevant fire schedule and the second code refers to the relevant spillage schedule IATA (International Air Transport Association) : provisions concerning the international carriage of dangerous goods by air IMDG (International Maritime Dangerous Goods code) LC50 : median Lethal Concentration LD50 : median Lethal Dose NFPA (National Fire Protection Association) or fire diamant NOEC (No Observed Effect Concentration) NVCI : National Poisoning Information Center OECD : Organisation for Economic Cooperation and Development

PBT Substances

persistent, bioaccumulative and toxic PNEC (Predicted No Effect Concentration) : concentration below which exposure to a substance is not expected to cause adverse effects REACH : Registration, Evaluation, Authorisation and restriction of Chemicals RID (Règlement concernant le transport International ferroviaire des marchandises Dangereuses) : Regulation concerning the International carriage of Dangerous goods by rail SCL (Specific Concentration Limits) TWA (Time-Weighted Average) : the average exposure over a specified period WGK (Wassergefahrdungsklasse) : a German classification of substances that indicate the environmental hazard for surface water

vPvB Substances

very persistent and very bioaccumulative Acute Tox. 4, oral : Acute toxicity, oral - Category 4 Eye Dam. 1 : Serious eye damage - Category 1 Met. Corr. 1 : Corrosive to metals - Category 1 Skin Corr. 1B : Skin corrosion - Category 1B Skin Irrit. 2 : Skin irritation - Category 2 STOT SE 3 : Specific Target Organ Toxicity - Single exposure - Category 3 This information is to our knowledge correct and complete on the date of issue of this safety data sheet. The information only concerns the product and does not give any guarantee for the quality and the completeness of the properties of the product, or in case of mixing or using in any other process. It remains the responsibility of the user to assure himself that the information is suitable and complete concerning the special use he makes of the product. BRENNTAG MATERIAL SAFETY DATA SHEET Revision nr : 10 Date: 3/3/2015 Supersedes : 20/3/2014 FERRIC CHLORIDE 40% Code : 12566 BRENNTAG denies all responsibility for loss or damage resulting from the use of these data. End of document BRENNTAG APPENDICES APPENDIX E – SAFETY RULES FOR BIOGAS SYSTEMS, GERMAN AGRICULTURAL OCCUPATIONAL HEALTH AND SAFETY AGENCY Safety Rules for Biogas Systems German Agricultural Occupational Health and Safety Agency This is a translation from the original German version entitled “Technische Information 4 Sicherheitsregeln für Biogasanlagen”. Every effort has been made to make it as accurate as possible, but the original German version should be the authoritative source. German Agricultural Occupational Health and Safety Agency Preface from Germany The safety rules for biogas systems explain and substantiate the requirements for the construction and operation of biogas systems in terms of the operating instructions of § 1 of the accident prevention regulations “Arbeits-stätten, bauliche Anlagen und Einrichtungen” [“Workplaces, Buildings, and Facilities”] (VSG 2.1) [(Regulations for Safety and Health 2.1)]. (German regulation) These rules intend to provide information to the planning office, the specialty company contracted for the construction, the operator and the employer regarding the construction and operation of agricultural biogas systems that are operated with operating pressures of less than 0.1 bar. The safety rules are the summary of the most important German regulations; they also provide information about rules to be followed. In addition, generally recognized engineering rules apply. For examples, see Appendix 11. Deviations are possible, if safety is guaranteed in the deviation. The German safety rules for biogas systems were recommended for implemen- tation on September 30, 2008, by the Advisory Board for Health and Safety. German Agricultural Occupational Health and Safety Agency 3 Table of Contents 1. General Information……………………………………………………….……………..7 1.1 Terminology……………………………………………………………………..7 1.2 Gas diagram of a biogas system…………………………………………...8 1.3 Properties of biogas…………………………………………………………...9 1.4 Hazard assessment…………………………………………………………….9 1.5 Operating instructions, instruction manuals, training………………….17 2. Parts of the System………………………………………………………………………19 2.1 General information………………………………………………………….19 2.2 Digester/Fermenter/Reactor……………………………………………….20 2.3 Liquid manure storage………………………………………………………22 2.4 Gas storage………………………………………………………………...…22 2.5 System control and process control engineering……………………...26 2.6 Gas processing………………………………………………………………. 27 2.7 Gas lines………………………………………………………………………..27 2.8 Instruments, safety equipment, and gas-carrying system parts…….29 3. Installation Rooms……………………………………………………………………….33 3.1 Gas firing systems……………………………………………………………..33 3.2 Combined heat and power unit (CHP)………………………………….33 3.3 Installation of gas-warning devices……………………………………….38 4. Operation…………………………………………………………………………………39 German Agricultural Occupational Health and Safety Agency 5 Appendices 1. Sample “Operating Instructions for Initial Startup/Restart of a Biogas System”………………………………………………………………………………….40 2. Sample “Inspection Document for Biogas Membrane Storage” and “Inspection Document for Gas-Carrying Pipes”………………………………..41 3. Sample “Operating Instructions for a Biogas System in Normal Operation”……………………………………………………………………………..43 4. Sample “Operations Log” ………………………………………………………….45 5. Sample “Operating Instructions for a Biogas System in the Case of Malfunction”…………………………………………………………………………...46 6. Sample “Operating Instructions for Shutting Down a Biogas System” ………………………………………………………………………...……….48 7. Sample “Operating Information – Liquid Manure and Biogases”………………………………………………………………………..……...49 8. Proposal for the Contents of an Alarm and Hazard Defence Plan ………………………………………………………………….…………………..51 9. Example Zone Classification………………………………………………………..53 10. Tightness of System Parts ……………………………………………..……………..58 11. Additional Regulations and Rules ………………………………………..……….63 12. Sample Test Plan for Work Material according to BetrSichV (Operational Safety Reg.) by Qualified Personnel of the Biogas System………………………………………………………………………………......66 13. Tightness Test for Gas-Carrying Container Parts and the Gas Storage …………………………………………………………………………...69 14. Information of the Property Insurer (GDV)……………………………………….71 Contacts…………………………………………………………………………..………..77 German Agricultural Occupational Health and Safety Agency 6 1. General Information 1.1 Terminology Biogas system: System for generating, storing, and utilizing biogas, including all equipment and buildings serving the operation. The generation results from the digestion of organic substances. Substrate: Organic substances to be digested. Digester (reactor, fermenter, digester): Container in which the microbial breakdown of the substrate occurs. Gas storage: Gas tight container or membrane bag in which the biogas is temporarily stored. Liquid manure storage: Containers and pits in the ground in which liquid manure, slurry, and the fermented substrate is stored. Machine room: Room containing the gas cleaning, gas conveying, or gas utilization equipment including the process control equipment. CHP unit: Combined heat and power plant that serves for generating power and heat. Potentially explosive areas, hazardous EX areas: Areas in which a dangerous, potentially explosive, atmosphere can occur due to local and operating circumstances. Zones: Potentially explosive areas are classified into zones according to the probability of the occurrence of a potentially explosive atmosphere. Safety distances: Areas around gas storage that protect the gas storage and its equipment. Gas processing: Equipment for cleaning and moisture removal of biogas. German Agricultural Occupational Health and Safety Agency 7 1. General Information Gas dome: Top of the digester container in which the biogas is collected and removed. Gas storage: Room or area in which the gas storage is housed. Explosive limits: If the concentration of biogas in the air exceeds a minimum value (lower explosive limit LEL), an explosion is possible. An explosion is no longer possible when the concentration has exceeded a maximum value (upper explosion limit UEL). Explosion range: Concentration in which combustible gases, mists, or vapours when mixed with air or another gas (supporting the combustion), can ignite. This range lies between the explosion limits. 1.2 Gas diagram of a Biogas System German Agricultural Occupational Health and Safety Agency 8 1. General Information 1.3 Properties of Biogas Biogas consists essentially of methane (50 to 80% vol.), carbon dioxide (20 to 50% vol.), hydrogen sulphide (0.01 to 0.4% vol.), and traces of ammonia, hydrogen, nitrogen, and carbon monoxide. The occurrence of particulate matter has to be factored in. Example: Methane 60% vol., carbon dioxide 38% vol., residual gas 2% vol. Biogas Natural Gas Propane Methane Hydrogen Heating 6 10 26 10 3 value (kWh/m³) Density 1.2 0.7 2.01 0.72 0.09 (kg/m³) Density ratio 0.9 0.54 1.51 0.55 0.07 to air Ignition 700 650 470 595 585 temperature (°C) Maximum 0.25 0.39 0.42 0.47 0.43 flame propagation speed in air (m/s) Explosion 6-12 4.4 – 15 1.7 – 10.9 4.4 – 16.5 4 – 77 range (% vol.) Theoretical 5.7 9.5 23.9 9.5 2.4 air requirement (m³/m³) 1.4 Hazard Assessment The basis for the development of a hazard assessment is to protect and to reduce the exposure to risk and hazards of employees. The employer must determine, evaluate, and minimize the hazards and must consider the acquired knowledge during design and selection of work tools, as well as the design of workplaces, work and production processes, work procedures, and interactions of all of the above . The hazard assessment must be continuously updated according to the current state of knowledge and new operating conditions. German Agricultural Occupational Health and Safety Agency 9 1. General Information The Labour Protection Law (ArbSchG of Germany) is the legal foundation for performing a hazard assessment. Supplementary requirements are found in the corresponding ordinances, such as the Ordinance on Industrial Safety, Ordinance on Bio-substances, or the Ordinance on Hazardous Substances. An obligation to document exists if there are more than ten employees. For activities with hazardous materials and bio-substances and in potentially explosive areas, the obligation to document applies regardless of the number of employees (Register of Hazardous Substances, Explosion Protection Document, etc.). As a matter of principle, in determining protective measures, technical protective measures are to be preferred, for example, the filling of closed systems compared to organizational protective measures, such as, the time separation between human presence and filling procedures. Personal safety measures, such as wearing respiratory equipment, come into use only when other protective measures have been exhausted. A hazard assessment must also be performed for maintenance and repair work, as well as when malfunctions are fixed. The following information must be considered within the scope of the hazards assessment: The Ordinance on Industrial Health and Safety (BetrSichV, Germany) regulates the provision and terms of work, equipment by the employer, the use of work equipment by the employees during work, and the operation of the systems re- quiring monitoring. Work equipment here includes all equipment that is used and serviced by employees, e.g., agitators, pumps, emergency flares, solids feeding equipment, gas condenser, combined heat and power units, etc. Due to Work Equipment and Systems Requiring Monitoring in Potentially Explosive Areas The Ordinance on Industrial Health and Safety regarding systems requiring monitoring applies also to operations without employees, if there is a need for monitoring. This rule applies to biogas systems, due to the danger of biogas German Agricultural Occupational Health and Safety Agency 10 1. General Information explosion. Systems in potentially explosive areas require monitoring, if they are, or contain, equipment, protection systems, or safety or control equipment according to Article 1 of the EU Directive 94/9/EU (ATEX). Examples Equipment: machines, resources with potential ignition sources (e.g., agitator), that can cause an explosion Protection systems: flashback arresters, pressure release valves Components: triggering devices for protection systems, for example, gas detectors Section 3 of the BetrSichV (Ordinance on Industrial Health and Safety) applies to all biogas systems, independent of the occupation or employment activity of the workers. Consequently, all biogas systems are subject to inspection obligations according to §§ 14 and 15 of the BetrSichV, regardless of the employment activity or occupation of the workers. § 12, Section 1, of the BetrSichV states that systems that require monitoring must be assembled, installed, and operated according to current state of the art technology. The current state of the art technology also includes the requirements of Section 2 of the BetrSichV for the operation. This implies, in principle, that an Explosion Protection Document is required according to § 6 BetrSichV. The operator bears the responsibility to ensure that changes to the system are also updated in the documentation, such as, the circuit diagrams, the operating instructions, the Explosion Protection Document, etc. The requirements of Appendix 4, Section A, in particular, No. 3.8, also apply to all biogas systems. Appendix 4, Section B, applies only to biogas systems that became operational after the BetrSichV came into effect. Here, the adjustments after a change/essential modification of a biogas system must be followed. Hazardous substances according to the Ordinance on Hazardous Substances are substances that have hazardous properties. Hazardous properties are, for German Agricultural Occupational Health and Safety Agency 11 1. General Information example, “harmful to health,” “poisonous,” “highly poisonous,” or “caustic.” Hazardous substances can be solid, in dust form, liquid, or can occur as an aerosol or as a gas. Examples 1. Hydrogen sulphide (H2S) 2. Carbon dioxide (CO2) Typical hazards • Danger of asphyxiation and/or poisoning due to fermentation in gas/ biogas intake areas. Release of highly poisonous gases such as hydrogen sulphide. • Hazards that occur particularly in systems that use additional substrates (waste, animal byproducts) along with renewable raw materials, liquid and solid manure: • increased release of hazardous gases such as hydrogen sulphide, especially during mixing due to the reaction of the substances being used. • Hazards during exchange of the activated carbon filter for gas cleaning.

Hazardous Ingredients

Assessment and protective measures: In principle, the development of hazardous gases must be prevented or minimized, to the greatest degree possible, or their release must be prevented or reduced. When using a chemical substance distributed by a supplier, the operator can use the material data safety sheet (MSDS) to assist the development of a hazard assessment. The MSDS is generally provided by the supplier of the chemical products. Before accepting delivered substances to be used, rapid tests should be performed, which can check important chemical properties – see information sheets for safety with biogas systems (List of Literature – Appendix 11). If mixing of different materials is required for operational reasons, no materials should be combined from which the generation of hazardous gas German Agricultural Occupational Health and Safety Agency 12 1. General Information concentrations due to reactions (e.g., acid-base reactions, large differences in temperature) could result. In particular, hydrogen sulphide can be released due to the addition of acidic components; ammonia can be released due to the addition of alkaline components. In order to be able to assess such reactions, operators of biogas systems must request the following information from the producers of the additional substrates and document in the daily operations log: Information About Substances Being Used • Waste code number, essential ingredients or substances, chemical struc- ture, pH value and additives, e.g., stabilizers, preservative agents, etc., • Origin information (e.g., from slaughterhouse, from the pharmaceutical production of Heparin ….), • Transport and delivery conditions (e.g., duration of transport, temperature …), and • Possible hazards (e.g., “can release hydrogen sulphide with the addition of acidic substances”). If the generation of hazardous gases, especially H2S, cannot be excluded, their release must be prevented or reduced, e.g., by closed filling, spatial separation or their forced discharge. Specific requirements for avoiding gas hazards can be found, for example, in Section 2.2.6 of the safety rules. Notes Hydrogen sulphide is a highly poisonous, colorless gas that smells like rotten eggs. It can be life threatening even at low concentrations. From a certain concentration, the sense of smell is disabled and the gas is not perceived. Substances with high sulphur content are, for example: • slaughterhouse waste • methionine from the animal • biomass waste (mycelia) from feed (feedstuff additive) biotechnical processes • residue from the generation of • rape-seed cake yeast • feedstuff residuals (e.g., soy • preservative agent sodium protein) bisulfite • food leftovers • additives, e.g., iron sulphate German Agricultural Occupational Health and Safety Agency 13 1. General Information 1.4.3 Biological Agents In the Ordinance on Bio-substances, “biological agents” are defined as microorganisms that can cause infections or have sensitizing or toxic effects in humans. These are primarily molds, viruses, and bacteria. Typical Hazards • inhaling dusts or aerosols containing molds, bacteria, or endotoxins, e.g., from moist silage or dry chicken manure. • additional hazards in systems using additional substrates (waste, animal byproducts) along with renewable raw materials, liquid and solid manure: biological agents in co-substrate (e.g., pathogens), hand contact during sorting. Assessment and protective measures The minimum necessary hygienic measures are described in TRBA 500 [Technical Rules for Biological Agents (Germany)]. Information for the assessment and protective measures can be found, for example, in the TRBA 230 (Agricultural Livestock Husbandry). Information for assessing hazards and concerning the use of technical and organizational protective measures for systems in which, along with, or instead of, renewable raw materials, substrates such as waste are used, can be found, for example, in the TRBA 214 (Biological Waste Treatment Systems: Protective Measures). The delivery area for liquid waste for digestion must be constructed in a way that an aerosol buildup is avoided. In certain concentrations, biogas can be explosive. Potentially explosive atmospheres must be effectively prevented. If the formation of a potentially explosive atmosphere cannot be prevented, effective ignition sources must be eliminated. This is achieved by eliminating the ignition of the potentially explosive atmosphere. German Agricultural Occupational Health and Safety Agency 14 1. General Information During the hazard assessment, for example, the following ignition sources must be considered: 1.4.4 Explosion Hazards Ignition Sources • Hot surfaces (Example: > 500°C (turbocharger)) • Open flames (Example: Fire, flames, embers) • Mechanically generated sparks (Example: Rubbing, beating, grinding) • Electrically generated sparks (Example: Switching operations, loose contacts, equalizing currents) • Exothermic reactions (Example: Spontaneous ignition of dusts) • Lightning • Electrostatic discharges Explosion hazards must be determined and assessed. In particular, it must be determined where potentially explosive atmospheres can occur. Potentially explosive areas are to be classified into zones according to Appendix 3 BetrSichV. Potentially explosive areas must be identified at their entrances by appropriate signage with black lettering on a yellow background. For example: 1.4.4.2 Classification of the Zones Potentially explosive areas are spaces in which a dangerous, potentially explosive atmosphere can occur due to the local situation and the operating conditions. Potentially explosive areas are classified into zones according to the frequency. German Agricultural Occupational Health and Safety Agency 15 1. General Information and duration of the occurrence of hazardous, potentially explosive atmospheres (for example, see Appendix 9). For areas that are subject to explosion hazards due to gases, the following applies: Zone 0 is an area in which hazardous, potentially explosive atmospheres are present constantly, over long periods, or frequently, as a mixture of air and combustible gases, vapours, or mist. Note The term “frequently” is used in the context of “predominant over time”. Zone 0 is practically never present with biogas systems during normal operation. Zone 1 is an area in which during normal operation a hazardous, potentially ex- plosive atmosphere can occasionally form as a mixture of air and combustible gases, vapors, or mists. Zone 2 is an area in which during normal operation a hazardous, potentially ex- plosive atmosphere as a mixture of air and combustible gases, vapours, or mists does not normally occur, or occurs only briefly. Explanation Normal operation according to Appendix 3 of the BetrSichV is defined in TRBS 2152, Section 2, paragraph 2, as a state during which the system is used or operated within its design parameters. It is not considered meaningful to view startup and shutdown of a continuously operating biogas system as normal operation. The startup and shutdown phase of a biogas system is a special operating state that requires separate preventative measures. These operating states should be given special consideration with corresponding operating instructions. 1.4.4.3 Requirements for Equipment in Potentially Explosive Areas Requirements in Zone 0 In Zone 0, only resources must be used that are approved for Zone 0 and that are appropriately labelled. Basically, only devices and protection systems of the Equipment Group II, Category 1 G, according to Appendix 1 of the Directive 94/9/EU, can be used. German Agricultural Occupational Health and Safety Agency 16 1. General Information Requirements in Zone 1 In Zone 1, only resources must be used that are approved for Zone 0 or 1 and that are appropriately labeled. Basically, only devices and protection systems of the Equipment Group II, Category 1 G or 2 G, according to Appendix 1 of the Directive 94/9/EU, can be used. Requirements in Zone 2 In Zone 2, only resources must be used that are approved for Zone 0, 1, or 2 and that are appropriately labelled. Basically, only devices and protection systems of the Equipment Group II, Category 1 G, 2 G, or 3 G, according to Appendix 1 of the Directive 94/9/EU, can be used. 1.5 Operating Instructions, Instruction Manuals, and Training The manufacturers introduce products into the market with operating instructions. The operating instructions from the component manufacturers must be collected and safely stored. During the transfer of manufacturer documentation for individual components, devices, and machines, ensure that the required operating instructions, including each of the required manufacturer’s declarations and, if applicable, the certificates of conformity, are present. Individual components or devices are, for example: • CHP components • flame detector • complete CHP unit • gas sensors • Agitators • level monitors • Pumps • pressure monitors • ventilating system • gas condensate system • switching systems • under and over-pressure • gas control path, or gas train protection, etc. • flashback arrester • condenser For the operation of different resources, equipment, etc., the operator has to create an instruction manual which includes content such as the operating instructions, as well as information about hazards that result from the installation conditions. German Agricultural Occupational Health and Safety Agency 17 1. General Information In addition, special operating states such as startup and shutdown of the system can be addressed using the instruction manual (see Appendix 1 and 6). The employees must be instructed regularly about safe operation, e.g., using the instruction manual. Additionally, with the use of external companies, for example, during corrective maintenance, servicing, and modifications, the instruction manual can be the basis to give the external company or employee what needs to be done (basis for a work order) and how. Tip The presence of visitors to a biogas system must be considered separately. Visitors must be instructed regarding the hazards in addition to what is permissible and prohibited. German Agricultural Occupational Health and Safety Agency 18 2. Parts of the System 2.1 General information Parts of the biogas system are equipment, constructions, buildings, and rooms that are necessary for the operation and safety of the biogas system. 2.1.1 Stability Parts that are placed out in the open, above ground must be securely built and protected against damage. They must be installed so that they are easily accessible. Sufficient stability must be guaranteed. 2.1.2 Potential equalization In order to eliminate the occurrence of potential differences, all electrically conductive system parts must be connected together, as well as to the protective conductor and the ground wire, corresponding to the VDE [German Electrical Engineering Assoc.] specification (Potential Equalization). 2.1.3 Gas conveying parts of the biogas system Gas conveying parts of the biogas system must be protected against impact and damage caused by chemicals and weather and, in hazardous areas, against mechanical influences and damage (e.g., areas where vehicles are operated, protected from collisions). 2.1.4 Maintenance and work platforms and operating parts In principle, maintenance and work platforms, as well as operating parts of agitators, pumps, and purging devices, must be placed above ground. If this is not possible, fixed, installed forced ventilation must be available. Sufficient air exchange must be guaranteed before entering (follow the instruction manual and warning signage). Note For additional information, see BGR 121 and BGR 126 [BGR – Occupational and Health Safety Rules]. German Agricultural Occupational Health and Safety Agency 19 2. Parts of the System 2.1.5 Connection points in gas lines Connection points in gas lines for non-stationary equipment, such as, mobile gas flares, must be equipped with shutoff valves. The shutoff valve must be built in before the connection of the non-stationary equipment, as viewed in the gas flow diagram. Operation must occur without hazard. 2.1.6 Fire Protection For information regarding equipping with fire extinguishers, refer to BGR 133 “Equipping Workplaces with Fire Extinguishers.” More extensive fire prevention measures must be coordinated with the responsible regional and specialist fire department offices. 2.2 Digester/Fermenter/Reactor 2.2.1 Thermal insulation The thermal insulation of the digester container must be at least normal combustibility, e.g., B2 DIN 4102. In the area of 1 m around openings, at which gas escapes during normal operation, the thermal insulation must be made from hard material that is difficult to ignite, e.g., B1 DIN 4102. Tip: See also, DIN EN 13501. 2.2.2 Manhole openings Manhole openings must have a clearance width of at least DN 800, or at least the dimensions 600 x 800 mm. If entry into a container is necessary for maintenance and repair work, sufficient ventilation must be possible; the same safety measures are necessary also with entry into inspection chambers. 2.2.3 Agitators Submersible motor agitators or submersible motor pumps must correspond to the protection type IP 68, and they must be operated only in the submersed condition. This should be specified in the operating instructions. 2.2.4 Safety installations Digester containers must be provided at all times with effective safety German Agricultural Occupational Health and Safety Agency 20 2. Parts of the System installations that prevent an inadmissible change of the internal pressure. The liquid seals must be designed and installed as safety seals, so that the sealing liquid does not spill out during overpressure or under- pressure and flows back again on its own during the alleviation of the overpressure or under- pressure. In the digester and post digester containers, it must be guaranteed that the fill levels are not exceeded, e.g., in that the fermented substrate is fed via a frost-free riser pipe (spillover) into the liquid manure storage. 2.2.5 Fill openings/plug screw feeder Fill openings, e.g., solids dosing feeders, should be secured so other objects do not fall. Measures to prevent other objects from falling in are, e.g.: • covered fill hoppers with a height > 1.30 m combined with a covering • fill funnels without a covering with a height of ≥ 1.80 m • fixed installation of grids with a bar grid of ≤ 20 cm • self-closing flaps with perpendicular openings • flushing gutters with which perpendicular openings are covered If the digester is filled by means of a plug screw feeder, a sufficient submersion must be present considering all operating states in order to prevent a possible gas escape. The submersion must correspond at least five-fold of the triggering pressure of the overpressure protection. 2.2.6 Protection equipment against gas hazards at fill openings In principle, the formation of hazardous gases must be prevented or minimized to the greatest extent possible, for example, through the preclusion of corresponding chemical reactions, temporally spaced fillings, or similar measures. If the formation of hazardous gases cannot be excluded, their release must be prevented or reduced, e.g., by appropriate filling technology in closed systems or by a spatial separation from other areas of the system. Fill openings should be arranged regarding the prevailing wind direction so that gases are led away from the operating area. In the case of arrangement in a building, it is compulsory to lead fermentation gases away. The equipment for leading fermentation gases away must German Agricultural Occupational Health and Safety Agency 21 2. Parts of the System definitely be turned on during filling. The satisfactory function of the suctioning equipment must be checked and documented before taking the system into operation for the first time. With fill funnels, if required, an operating platform must be provided for the safe operation of flushing hoses. The gas hazard must be indicated in the immediate surroundings of the filling device. If the occurrence of gases in hazardous concentrations in the fill areas is not excluded, warning of the gas hazard, in particular, due to hydrogen sulphide, must be guaranteed through the use of appropriate gas-warning devices. 2.2.7 Discontinuous digestion (e.g., batch) No gas hazards must arise during feeding and removal. 2.2.8 Containers with fluctuating fill levels The operation of containers with strongly fluctuating fill levels, such as post digesters or gas tight final storage, must be considered separately, e.g., with regard to explosion protection, due to the changing fill levels. 2.3 Liquid manure storage The accident prevention regulations of the Agricultural Occupational Health and Safety Agency apply to the construction, equipment, and operation. 2.4 Gas storage Gas storage must be constructed, maintained, and operated such that the safety of the system operators, service personnel, and others is guaranteed. 2.4.1 Gas storage (pressure < 0.1 bar) Gas storage must meet the requirements for being gas tight and resistant to pressure, media, UV, temperature, and weather. German Agricultural Occupational Health and Safety Agency 22 2. Parts of the System For the selection of materials, especially for plastic membranes, the following requirements must be met: • tensile strength minimum 500 N/5 cm or • tensile strength 250 N/5 cm • gas permeability with respect to methane < 1000 cm³/m² x d x bar • temperature resistance for the use case (mesophilic, thermophilic digestion process) • gas storage must be checked for tightness before being in operation (Appendix 13) 2.4.2 Safety installations An inadmissible change of the interior pressure must be prevented by continuously effective safety installations. 2.4.3 Ventilation and exhausting of gas storage rooms Installation rooms for the gas storage must have effective ventilation (cross ventilation). Diagonal ventilation should be attempted. The supply air opening should be placed in the area of the floor, and the exhaust air opening should be placed below the ceiling. The supply air and exhaust air opening must each have the following minimum cross sections: Gas Storage Volume Cross Section up to 100 m³ 700 cm² up to 200 m³ 1,000 cm² above 200 m³ 2,000 cm² 2.4.4 Doors Doors must open outwards and must be lockable. 2.4.5 Safety distances To avoid mutual impact in the case of damage, preventing flashover to adjacent systems in the case of fire, and for the protection of the gas storage from damage, such as heating as a consequence of fire, safety distances of at German Agricultural Occupational Health and Safety Agency 23 2. Parts of the System least 6 m must be provided in the horizontal direction between the gas storage and adjacent systems, equipment, or buildings (with a height lower than 7.5 m) not belonging to the biogas system, or to pathways or transport paths. For a building height > 7.5 m (gas storage or building not belonging to the system), the following applies: 0.4 x H1 + 3m For two building heights (gas storage or building not belonging to the system) greater than 7.5 m, the following applies: 0.4 x H1 + 0.4 x H2 Within the biogas system, a safety distance of at least 6 m must be provided be- tween the gas storage and the installation room for the combustion motors (see Section 2.4.5.2). 2.4.5.1 Dimensioning of the safety distances For above ground installations, the safety distance is measured from the upright projection of the edge of the storage container. 2.4.5.2 Protective wall The safety distance can be reduced through sufficient earth covering or sufficiently dimensioned safety wall or fire protection insulation (e.g., firewall). Doors in the protective walls must be fire resistant and self-locking (T 90 according to DIN 4102). A protective wall can also be an appropriately designed building wall without openings. The height and width of the protective wall must comply with the guidelines of the respective regional building code. German Agricultural Occupational Health and Safety Agency 24 2. Parts of the System 2.4.5.3 Requirements within the safety distance Within the safety distances: • Without advanced protective measures, there must be no storage of combustible substances in quantities over 200 kg; no other buildings and no public streets or paths can be located there. Advanced protective measures can be, for example, fire prevention measures, fire protection measures; fire-fighting measures (for example, see the section on protective walls). • Transport paths, necessary for the system, are permissible. • Without advanced protective measures, machines and activities, which can lead to an endangerment of the gas storage, are prohibited (e.g., welding, thermal cutting). • Gas flares must not be operated. • Fire, open flames, and smoking are prohibited. ....................................................................................13 4.4. Biological agents ...........................................................................................13 4.5. Hazards from electrical equipment ...................................................................14 4.6. Mechanical hazards .......................................................................................14 4.7. Gas hazards ..................................................................................................14 4.8. Explosion and fire hazards ...............................................................................15 4.9. Sources of danger from the surrounding environment .........................................16 4.10. Hazards arising from inappropriate behaviour ..................................................16 5. Hazard assessment ..................................................................................................17 5.1. Hazard assessment for specific operating states .................................................19 5.2. Start-up/commissioning .................................................................................19 5.3. Maintenance and repair work...........................................................................19 5.4. Shut-down/decommissioning ..........................................................................21 5.5. Explosion protection document........................................................................21 5.6. Requirements for work equipment in hazardous areas ........................................23 6. Fire protection concept .............................................................................................24 6.1. Structural fire protection .................................................................................24 6.2. Organisational fire protection ..........................................................................25 7. Protective measures .................................................................................................26 7.1. Organisational protective measures ..................................................................26 7.2. Personal protective measures ..........................................................................28 8. Documentation ........................................................................................................30 Specific requirements ......................................................................................................31 1. Requirements for feeding systems ..............................................................................31 2. Requirements for substrate treatment systems ............................................................33 3. Requirements for holding tanks/preliminary pits ..........................................................34 2 4. Requirements for the digester ....................................................................................35 5. Requirements for the gas storage tank ........................................................................37 6. Requirements for wooden roof structures in gas storage systems ....................................39 7. Requirements for installation rooms for gas storages.....................................................40 8. Requirements for substrate-carrying parts of the biogas plant ........................................41 9. Requirements for gas-carrying parts of the biogas plant ................................................42 10. Requirements for condensate traps ..........................................................................43 11. Requirements for overpressure and underpressure protection devices ...........................44 12. Requirements for gas purification .............................................................................45 12.1. Internal desulphurisation through the supply of air to gas spaces in the digester ...45 12.2. Internal desulphurisation through the addition of iron compounds ......................45 12.3. Desulphurisation by means of ferrous materials or activated carbon in external facilities ......................................................................................45 13. Requirements for gas analysis .................................................................................46 14. Requirements for fittings and safety devices exposed to gas.........................................47 15. Requirements for gas flares .....................................................................................47 16. Requirements for process control system/instrumentation and control (I&C) system .......48 17. Requirements for electrical engineering ....................................................................49 17.1. Equipotential bonding ...................................................................................49 17.2. Protective measures in the event of a power outage ...........................................50 18. Requirements for lightning protection .......................................................................52 19. Requirements for rooms with substrate-carrying and / or gas-carrying plant parts ............52 Inspections and tests........................................................................................................54 Upgrading of biogas to biomethane ....................................................................................55 Recommendations for safe plant operation ..........................................................................58 1. Recommendations for the legal framework ..................................................................59 2. Training in the industry .............................................................................................59 Annexes ..........................................................................................................................60 Annex 1: Hazard assessment .........................................................................................60 Annex 2: Instruction record for subcontractors and employees for maintenance, installation and repair work ..............................................................................61 Organisations ..................................................................................................................64 References ......................................................................................................................66 Credits............................................................................................................................67 3 Quotes ‘Biogas is a key component of decentralised renewable energy supply, but it will only achieve long-term acceptance if biogas plants are operated in a professional manner. It is just as important to observe the state of the art in this field as in other forms of power generation. This means that everyone involved, manufac- turers, distributors and operators, must comply with relevant regulations and requirements (in particular European directives such as the Machinery Directive 2006/42/EC and the ATEX Directive 2014/34/EU). They must properly assess any hazards that may exist in relation both to occupational health and safety and to protection of the environment, and then formulate and implement the neces- sary protection measures. This implies a certain technical challenge in order to understand the process engineering underlying the plant acquired from the manufacturer, but also an organisational challenge in the need to prepare the supporting documents. In Germany, for example, the German Biogas Association (Fachverband Biogas e.V.) constantly collaborates with authorities and specialised bodies to deal with complex issues and find practical solutions. A huge range of working aids, fact sheets etc. have been produced, the principal content of which we are pleased to be able to present to you in this publication. After all, as I said: only safe plants will ensure the acceptance of biogas over the long term.’ – Josef Ziegler, Spokesperson of the Safety Working Group of the German Biogas Association ‘In the area of renewable energy and energy efficiency, GIZ is currently imple- menting more than 170 projects in over 50 countries, of which more than 20 focus on biogas or have a biogas component. Thus, from a development policy perspective it is well known that biogas has a lot of advantages, like the reduction of greenhouse gas emissions, provision of reliable green energy and the creation of jobs. In comparison to Germany, most of our partner countries do not have specific requirements concerning safety in biogas plants. Moreover, it is obvious that pos- sible accidents in biogas plants are very harmful for sustainable biogas market development. The issue of safety is therefore an important part of our work and crucial to our partners in order to make sure that biogas projects become sustain- able, efficient and safe.’ – Bernhard Zymla Head of Energy and Transport Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH 4 Foreword For the operation of biogas plants to be sustainable, efficient and reliable, safety is a matter of crucial importance. Biogas is classified as a highly flammable mixture of gases that can be harmful to health when inhaled because of its toxic constituents. The process engineering sys- tems used in biogas plants can be highly complex. Given such many and varied ha- zards, it is extremely important to have fundamental protective measures in place in order to keep the risks from biogas plants for people and the environment to an absolute minimum. These Safety Guidelines for biogas plants provide a comprehensive description of the issue of safety in biogas plants and point to various forms of practical assistance, based to a large extent on the recommendations of the Technical Information 4 of the Social Insurance for Agriculture, Forestry and Horticulture (SVLFG). The Safety Gui- delines therefore constitute an essential source of information for everyone involved in the planning, construction, operation, maintenance and testing of biogas plants. In addition, this publication – which came into being in cooperation with the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH – is meant to provide a basis for policy-makers to develop possible national frameworks and safety standards. The Guidelines focus on biogas plants in the medium and large size segments. Micro plants and domestic biogas plants are not discussed in detail in this publication. Apart from raising awareness of the issue of safety, the aim of this brochure is also to present proposals for internationally applicable safety requirements for biogas plants. Attention is primarily directed at occupational health and safety, in other words the protection of operators, employees and other individuals (third parties). The Guidelines are basically divided into two main sections: general requirements, covering important topics such as the various dangers and hazards presented by a biogas plant, and specific requirements, such as those applying to parts and compo- nents of a biogas plant. Furthermore, requirements for biomethane production are also mentioned. In the final section, the German Biogas Association gives advice on the development of standards for biogas safety. Biogas has many advantages – it is decentralised, climate-friendly and reliable – and is a safe form of energy, provided that certain rules are observed. Through this pub- lication, the German Biogas Association and GIZ hope to play a part in helping the wide-ranging experience gained with this topic in Germany be put to use in advancing the issue of safety in biogas plants on international markets. 5 General requirements 1. Introduction t is immensely important that biogas plants are ing this period were of a mechanical nature (being operated safely, given the highly complex pro- struck by something, falling, getting cut, crushed, cess engineering involved and the fact that high- etc.). Of the accidents analysed, almost 50 % hap- ly flammable gases are produced and stored. pened during maintenance activities and less than However, if the appropriate protective measures 1 % resulted in persons being fatally injured. I are taken, hazards in and around biogas plants can be limited and reduced to the extent that the poten- The application of toxic, harmful and/or sensitising tial threats are manageable and the plant is operated chemicals to the process – the processing aids, bio- in the intended manner. To ensure that a plant can logical agents or compounds used to desulphurise be operated safely, it must be borne in mind that bi- the biogas – was also a cause of various accidents in ogas safety starts right from the planning phase and biogas plants in Germany. continues through the whole operation of the plant, requiring close collaboration between manufactur- This illustration presents the situation in Germany at ers, planning consultants and operators. the time when the survey was conducted. Thanks to the high safety standards, accidents resulting in per- But even if various technical, organisational and sonal injury, for example those caused by explosion personal protective measures are in place, threats to or fire, are relatively rare. In other countries these people and nature may still occasionally arise from statistics may look completely different. It is clear, biogas plants. The Social Insurance for Agriculture, therefore, that compliance with specific provisions Forestry and Horticulture (SVLFG) is the organisation (legislation, sets of regulations, standards) can in- responsible for work insurance for farmers in Ger- deed have a substantial influence on safety in biogas many, among other services. In 2012 it analysed the plants and significantly improve it. personal injuries suffered by workers at biogas plants between 2009 and 2012. As shown in Figure 1, the most common accidents at biogas plants dur- Types of accidents with injured persons at biogas plants Figure 1: Types of hazard relating to accidents resulting in personal injury (SVLFG, 2012) 7 % 4 % 1% Mechanical 1% Chemical Thermal Radiation Noise Not specified 86 % 6 General requirements 2. Terms and definitions Ammonia (NH3) Nitrogenous gas arising from the degradation of nitrogen-containing compounds such as protein, urea and uric acid. Anaerobic treatment Biotechnological process taking place in the absence of air (atmospheric oxygen) with the aim of degrading organic matter to recover biogas. Biogas Gaseous product of anaerobic digestion, comprising primarily methane and carbon dioxide, but which, depending on substrate, may also contain ammonia, hydrogen sulphide, water vapour and other gaseous or vaporisable constituents. Biogas plant Plant designed for the production, storage and use of biogas, including all equipment and structures serving the operation of the plant; gas is produced from the anaerobic digestion of organic matter. Biogas upgrading to Process for separating methane and carbon dioxide and for reducing other biomethane undesirable gaseous constituents (H2S, NH3 and other trace gases). The product gas has a high methane content (similar to natural gas) and is referred to as biomethane. Biomethane Biomethane is a gaseous, biologically produced fuel, the main constituent of which is methane and which conforms to the national standards for natural gas. Carbon dioxide (CO2) Colourless, non-combustible, slightly sour smelling, in itself non-toxic gas formed along with water as the end product of all combustion processes; concentrations of 4–5 % in air have a numbing effect, and concentrations above 8 % can cause death from asphyxiation. Condensate Biogas produced in the digester is saturated with water vapour and must be dehydrated before it is used in the CHP unit. Condensation takes place either via an appropriately situated underground pipe in a condensate separator or by drying of the biogas. Combined heat and power Unit for the conversion of chemically bound energy into electrical energy and (CHP) unit thermal energy on the basis of an engine linked to a generator. Simultaneous conversion of released energy into electrical (or mechanical) energy and heat intended for use (useful heat). Desulphurisation A physio-chemical, biological or combined method of reducing the hydrogen sulphide content in biogas. Digestate Liquid or solid residue from biogas recovery, containing organic and inorganic constituents. Digestate storage tank Container or pond in which liquid manure, slurry or digested substrate is stored (liquid-manure pond) before subsequent use. Digester Container in which microbiological degradation of the substrate takes place (reactor, digestion tank) and biogas is generated. Explosive range Concentration at which combustible gases, mists or vapours in a mixture with air or another gas supporting combustion can be ignited. 7 General requirements Explosive limits If the concentration of biogas in air exceeds a minimum value (lower explosive limit, LEL), an explosion may occur. An explosion is no longer possible if the concentration exceeds a maximum value (upper explosive limit, UEL). Gas storage tank Gas-tight tank or membrane gas holder in which biogas is held in temporary storage. Gas purification Facilities for purifying biogas (e.g. desulphurisation). Hazardous area/Ex zone: Area in which a dangerous explosive atmosphere may occur due to local and operational conditions. Hydrogen sulphide (H2S) Highly toxic, colourless gas that smells of rotten eggs; can be life-threatening even in low concentrations. Installation room Room where gas purification, gas pumping, gas analysis or gas utilisation equipment is installed, including the associated instrumentation and control equipment. Methane (CH4) Colourless, odourless and non-toxic gas; its combustion products are carbon dioxide and water. Methane is one of the most significant greenhouse gases and is the principal constituent of biogas, sewage treatment gas, landfill gas and natural gas. Normal cubic metre Nm3 One normal cubic metre is the amount corresponding to one cubic metre of or mN 3 gas at a pressure of 1.01325 bar, humidity of 0 % (dry gas) and a temperature of 0˚C. Nitrogen oxide The gases nitrogen monoxide (NO) and nitrogen dioxide (NO2) are referred to collectively as NOx (nitrogen oxides). Nitrogen monoxide is a toxic but colourless and odourless gas. Nitrogen dioxide is a reddish-brown, toxic gas that has a pungent smell similar to chlorine. They are formed in all combustion processes as a compound of atmospheric nitrogen and oxygen, but also as a result of oxidation of nitrogenous compounds contained in fuel. Safety distance Area around gas storage tanks for the protection of the tank and its equipment. Solids feeding system Part of a biogas plant used for loading non-pumpable substrates or substrate mixtures directly into the digester. Substrate Raw material for anaerobic digestion or fermentation. Sulphur dioxide (SO2) Colourless, pungent-smelling and toxic gas that irritates the mucous membranes. In the atmosphere, sulphur dioxide is subjected to a range of conversion processes which result in the formation of various substances including sulphurous acid, sulphuric acid, sulphites and sulphates. 8 General requirements 3. Properties of biogas Biogas essentially consists of methane (50 to 75 % by hazards. P statements are safety instructions that volume), carbon dioxide (20 to 50 % v / v), hydrogen describe general precautions, preventive measures, sulphide (0.01 to 0.4 % v / v) and traces of ammonia, responses (measures to be taken following an acci- hydrogen, nitrogen and carbon monoxide. In addition, dent), storage instructions and disposal instructions. it may contain volatile substances. An example of the composition of biogas from an average biogas plant using manure: methane 60 % v / v, carbon dioxide Further information is available 38 % v / v, residual gases 2 % v / v (see Table 1). on the website of the Globally Harmonized System of Classification According to the Globally Harmonized System of and Labelling of Chemicals (GHS). Classification and Labelling of Chemicals (GHS) (United, 2015), biogas is described as an extremely flammable gas (H220) and it should be kept away 1.3.1. Density from heat, hot surfaces, sparks, open flames and other ignition sources, such as smoking (P210); it The density of biogas may vary, depending on its should be stored in a tightly closed container (P233) composition, moisture content and temperature. Bi- and in a well-ventilated place (P403 + P235). Haz- ogas may be heavier or lighter than air, and does not ard and precautionary statements (H and P state- separate under the influence of gravity. This property ments or phrases) are brief safety instructions con- must be borne in mind when determining protective cerning the use of chemicals. H statements describe measures (e.g. the positioning of fixed gas warning physical hazards, health hazards and environmental systems). Table 1: Properties of various gases (SVLFG, 2016). Biogas (60 % CH4) Natural gas Propane Methane Hydrogen Heating value (kWh / m3) 6 10 26 10 3 Density (kg / m3) 1.2 0.7 2.01 0.72 0.09 Density relative to air 0.9 0.54 1.51 0.55 0.07 Ignition temperature (°C) 700 650 470 595 585 Max. flame propagation speed in air (m / s) 0.25 0.39 0.42 0.47 0.43 Explosive range (% v / v) 6 – 22 4.4 – 15 1.7– 10.9 4.4 – 16.5 4 – 77 Theoretical air consumption (m3 / m3) 5.7 9.5 23.9 9.5 2.4 9 General requirements Biogas plants are complex process engineering sys- not least biogas itself also presents risks. Attention tems in which a range of different hazards can occur. also needs to be paid to mechanical hazards in cer- Essentially, the hazards can be divided into health tain parts of the plants. hazards and environmental hazards. Figure 2 shows the principal hazards in relation to Possible hazards at biogas plants include fires and the respective parts and components of a biogas explosions, for example, but also dangerous sub- plant. In this diagram the focus is on health hazards. stances (e.g. processing aids), electric current and Figure 2: Overview of hazards in biogas plants 17 7 13 31 6 8 12 23 28 22 11 33 16 5 25 24 15 21 26 29 32 4 10 20 19 34 35 36 9 1 30 2 37 3 18 27 14 Electrical 1 Feeder 8 Gas storage Hazardous 2 Dosing station for 9 Digester substances processing aids 10 Observation window 3 Potential equalisation 11 Low pressure monitor 4 Access opening 12 Over- and underpressure protection Explosion 5 Shut off valve 13 Blow off pipe 6 Return valve 14 Condensate trap 7 Air injection for the biological desulphurization Fire hazards Mechanical 10 General requirements 17 7 13 31 6 8 12 23 28 22 11 33 16 5 25 24 15 21 26 29 32 4 10 20 19 34 35 36 9 1 30 2 37 3 18 27 14 15 Shut off valve 24 Compressor 32 Emergency switch 16 Flame arrester 25 Gas-counter 33 Air outlet 17 Gas flare 26 Manometer 34 Upgrading unit 18 Fire protection for the wall entry 27 Flame arrester 35 Conditioning unit of the gas pipe 28 Gas warning device 36 Injection unit 19 Fresh air inlet 29 CHP 37 Utilization of biomethane 20 Autmoatic shut-off device (Combined Heat and Power Unit) 21 / 22 Gas fine filter / Activated 30 Oil tray carbon filter 31 Exhaust pipe CHP 23 Low pressure monitor 11 General requirements 2013). Additional hazards that may arise in plants where Hazardous substances are substances, materials or other substrates are used beside energy crops, liquid mixtures that exhibit certain hazardous proper- manure and solid manure: biological agents in co- ties. Such hazardous properties include ‘harmful to substrates (e.g. pathogens); manual contact during health’, ‘toxic’, ‘very toxic’, ‘corrosive’, ‘sensitising’ sorting. and ‘carcinogenic’. Hazardous substances can take the form of solids, liquids, aerosols or gases. Hazardous substances that are particularly likely to be present at biogas plants are biogas, processing aids, oils, activated carbon, silage effluent, slurry, wastes and biological agents. Typical hazards include: „ Risk of asphyxiation and/or poisoning by fermen- tation gases / biogas in feedstock receiving areas. Release of highly toxic gases such as hydrogen Bräsel sulphide in the receiving area, especially during mixing, as a result of reactions between feed- Martina stock materials. photo: 13 General requirements Various risky agents and materials are also liable to 4.6. Mechanical hazards arise in the course of waste treatment. These may include impurities (interfering substances), ani- Mechanical hazards are usually not specific to biogas mal carcasses, or wastes from hospitals, doctor’s technology. However, the most common types of ac- practices or households with people who are sick or cident at biogas plants are attributable to mechani- in need of care (e.g. used syringes and cannulas). cal hazards: falling, impact, crushing, cutting. Biological agents can also be introduced by rodents, birds or other animals and their excrement. Accident blackspots in this connection include work on the silo or other workplaces at a height, work in 4.5. Hazards from electrical equipment the vicinity of rotating parts (e.g. feeding systems) or work in the vicinity of moving vehicles (risk of being A variety of electrical equipment is used in biogas run over). Accidents are particularly likely to occur plants (control equipment, CHP unit, pumps, agi- during maintenance and repair work if inadequate tators, measuring instrumentation, etc.). Under protective measures have been taken. certain circumstances this equipment may have adverse effects on health as a result of electrical 4.7. Gas hazards hazards from the presence of electrical energy. Biogas is a mixture of different gases, the concen- „ Danger of electric shock or arc caused by an tration of which may vary depending on the plant electric shock through an individual’s body or in question. Key constituents of biogas are listed by an arc flash. below, along with their properties regarding risks to Example: damaged power cables on agitators health (see Table 2). „ Danger from electric or magnetic fields from irritant effects in the human body created by the The workplace exposure limit (TRGS 900, 2016) circulation of induction currents caused by elec- or occupational exposure limit (OEL) is the time- tric fields, induced currents or magnetic fields. weighted average concentration of a substance in air These effects occur in a frequency range up to at the workplace over a specified reference period at 30 kHz (low-frequency range). which no acute or chronic harm to the health of em- Example: electromagnetic, electrical and mag- ployees is expected to be caused. As a rule, the limit netic radiation from the generator of the CHP is set on the assumption that the exposure is for eight unit (danger for people with pacemakers). hours a day, five days a week over a working lifetime. „ Danger from static electricity caused by an elec- The workplace exposure limit is specified in units of tric shock from the discharge of static electricity. mg / m³ and ml / m³ (ppm). Table 2 Properties of the gaseous constituents of biogas. Sources (TRGS 900, 2016) and (SVLFG, 2016) Properties Hazardous Workplace atmosphere exposure limit CO2 Colourless and odourless gas. Heavier than air. 8 % v / v, danger of asphyxiation. 5500 ppm NH3 Colourless and pungent-smelling gas. Lighter Above 30 – 40 ppm mucous membranes, 20 ppm than air. respiratory tract and eyes become irritated. Above 1000 ppm breathing difficulties, potentially inducing loss of consciousness. CH4 Colourless, odourless gas. Lighter than air. 4.4 – 16.5 % - H2S Highly toxic, colourless gas. Heavier than air. Above a concentration of 200 ppm the sense of 5 ppm Smells of rotten eggs smell becomes deadened and the gas is no longer perceived. Above 700 ppm, inhaling hydrogen sulphide can lead to respiratory arrest. 14 General requirements Mühling Uwe photo: 4.8. Explosion and fire hazards People within the exploding cloud can suffer fatal lung injury. Away from the cloud, ear damage and An explosion is defined as the sudden chemical re- damage from missiled objects is possible. action of a flammable substance with oxygen, re- leasing large amounts of energy. There is a sudden If the concentration of biogas in the atmosphere is expansion in the volume of gases as the energy is between 6 and 22 % v / v, there is a risk of explosion released. This can be brought about by an explosive in the presence of an ignition source (explosive range, atmosphere, for example. explosive atmosphere). In the case of pure methane gas, the explosive range is between 4.4 and 16.5 % Flammable substances may be present in the form v / v. The ignition temperature of biogas is 700°C of gases, vapours, mists or dusts. An explosion can (methane 595°C). The composition of biogas may vary only occur if three factors apply simultaneously: with regard to the proportions of methane and carbon dioxide, with the result that the explosive range of the „ flammable substance (in distribution and gas mixture in the presence of air also varies. concentration conducive to explosion) „ oxygen (from air) Figure 3 therefore shows by way of example the ex- plosive limits of a methane/carbon dioxide mixture „ source of ignition (70 % CH4 – 30 % CO2) and their trend (upper and Depending on the circumstances, two types of ex- lower limit). Gas-air mixtures above or below the ex- plosion can take place in biogas plants: detonation plosive range are not ignitable. and deflagration. A deflagration is characterized by a subsonic flame propagation. The overpressure level resulting from a deflagration depends on the flame Figure 3: Explosion triangle for biogas speed, which depends on the turbulene and number of objects in the combustion zone. In a completely 0 100 unconfined area the overpressure is limited while a confined space can result in significant overpres- Mixture Methane/CO2 20 sures. Lower levels of overpressrue can result in ear 80 70/30 damage and bruises and cuts from missiled objects. Higher levels can damage a building and as a result of that als injure people in and around that building. 40 CH4 in Vol.-% 60 A detonation is characterized by supersonic flame propagration velocities and always creates high 60 CO2 in Vol.-% 40 overpressures. If many obstacles are present in the combustion zone or if gas expansion is limited due to 80 partial confinement, the flame speed may accelarate 20 from subsonic to supersonic levels. This is called UEL Explosion range the ‘deflagration to detonation transition’ (DDT). LEL 100 The overpressure from a detonation is high enough 0 to destroy builings within the exploding cloud or to 100 80 60 40 20 0 seriously damage buildings away from the cloud. Air/CO2/CH4 in Vol.-% 15 General requirements Example of a ripped gas storage VersicherUngen Vgh photos: There are various potential sources of ignition in 4.9. Sources of danger from the surrounding biogas plants (see Table 3). Microorganisms Protection for the eyes and face if spraying or squirting of infectious (airborne) materials or liquids can be expected and technical measures do not Aerosols provide adequate protection. Biogas (constituents) Tasks for which respiratory protection is used must be expressly Additives and auxiliary materials considered in the hazard assessment. Suitable respiratory protection must meet the following requirements as a minimum: „ Half mask with class P2 particle filter to DIN EN 143 or FFP2 particle-filtering half mask to DIN EN 149. „ Filtering half masks with exhalation valve are the preferred choice. If biogas is released, closed-circuit self-contained breathing apparatus must always be used because of the possibility of high concentrations of H2S and of oxygen displacement. Moulds Heavy-duty, liquid-impermeable and low-allergen gloves, also with (skin contact) extended cuffs in order to prevent liquid contamination with pathogens Bacteria from entering the gloves. The gloves must be resistant to the disinfec- Viruses tants being used. Endotoxins Protection for the eyes and face if spraying or squirting of infectious materials or liquids can be expected and technical measures do not Additives and auxiliary materials provide adequate protection. Waterproof aprons, if it can be expected that clothing will become soaked. Waterproof footwear, if it can be expected that footwear will become soaked. Electrical hazards Static discharge Safety shoes that conform at least to the requirements of protection class S2 and safety boots that conform at least to the requirements of Defective cables protection class S4 according to DIN EN ISO 20345 should be provided. Mechanical hazards Falling, stumbling, crushing, cutting Safety shoes that conform at least to the requirements of protection class S2 and safety boots that conform at least to the requirements of protection class S4 according to DIN EN ISO 20345 should be provided, as well as weatherproof clothing as required. (TRGS 727, 2016) Fire and explosion Personnel can become statically In hazardous areas classified as zone 0, 1 or 20, conductive footwear charged, for example when walking, with a leakage resistance to earth of less than 108 Ω should be worn. when standing up from a chair, when The same requirement applies in zone 21 in the case of dusts with a changing clothes, when handling plastics, when carrying out work minimum ignition energy (MIE) ≤ 10 mJ. involving pouring or filling, or through Work clothing or protective clothing must not be changed, removed or induction when standing in proximity put on in hazardous areas classified as zone 0 or 1. to charged objects. A statically char- Personal protective equipment must not become dangerously charged ged person touching a conductive in hazardous areas or in the presence of explosive gas mixtures, for object, e.g. a door handle, causes spark discharges. example during maintenance work or on emergency call-outs. (TRGS 727, 2016) 28 General requirements Basic hygiene measures must be ensured. These „ Microbiologically contaminated clothing must include washing hands before going for breaks and not be cleaned at home. upon completion of work, as well as regular and „ If pests such as rodents, pigeons, insects or need-based cleaning of the workplace and cleaning/ other animals gain access to the working area, changing of work clothing and personal protective regular pest control is essential. equipment. The measures could be laid down in a „ Storage conditions that encourage biological cleaning and hygiene plan. Employees must refrain agents to multiply must be avoided, in as far as from eating or drinking at workplaces where there is operation of the plant allows. a risk of contamination by biological agents. If the hazard assessment calls for disinfection measures, „ Adequate ventilation of the working area must these must be carried out with tested disinfectants. be provided in accordance with the hazard as- sessment. „ No one wearing microbiologically contaminated work clothing is permitted to enter break rooms Figure 12 provides an overview of the various ele- or staff rooms. ments of personal protective equipment. It should be noted that not all elements need to be used in „ Wastes containing biological agents should each instance. The need to wear a helmet or a fall ar- be collected in suitable containers. rest system, for example, depends on the situation. „ Work clothing and personal protective equip- ment should be kept separate from private clothing. Figure 12: Personal protective equipment (PPE) safety helmet safety glasses hearing protection filter mask weather protection (reflective workwear) catching systems safety gloves safety shoes Further information on the technical requirements for personal protective equipment can be found in the following standards: DIN EN 143: Respiratory protective devices - Particle filters - Requirements, testing, marking DIN EN 149: Respiratory protective devices - Filtering half masks to protect against particles DIN EN ISO 20345: Safety footwear 29 General requirements 8. Documentation TIP Maintenance contracts with specialist com- The following items must be documented, in accord- panies are particularly advisable for parts of ance with national requirements: ! the plant that are of relevance to safety and need „ Responsibilities / rights to issue instructions: list to be regularly calibrated (e.g. gas warning sys- of phone numbers of persons to contact (both tem, gas analyser, gas detector, personal protec- internal and external, e.g. authorities, agencies). tion monitor, fire detector). „ Emergency plan (operating instructions for proce- dures in the event of accident, fire, explosion, the As a rule, the plant operator is responsible for proper release of substrate, power outage, prevention of documentation, i.e. ensuring that the documenta- unauthorised persons from gaining entry etc.) tion is complete, up-to-date, of the appropriate „ Hazard assessment/explosion protection quality and in conformance with the respective legal document provisions in the country concerned. In individual „ Operating instructions for the employees cases it should be clarified what consequences there „ Instruction manuals from the manufacturer would be under liability law in the event of an in- „ Hazardous substances register fringement of the applicable law. „ Safety data sheets The documentation should be readily available at all „ Release/briefing forms times; it should be kept at the biogas plant. A backup „ Maintenance and repair plan (including schedule copy of the documents should be kept at alternative according to manufacturer’s instructions) locations. This is particularly important in emergen- „ Regular tours of inspection and operation diary cies or in the event of faults. In such instances the operator must make arrangements for deviations „ Evidence of recurring tests (electrical tests, from normal operation in order to ensure that the tests of work equipment) plant reverts to normal operation as quickly as pos- „ Evidence of initial and recurring training courses sible or to minimise the extent of the disruption. „ Plans of present inventory of facilities and equip- ment (floor plan for firefighting, piping and in- strumentation diagram, piping layout plan, etc.) „ Process management matrix „ Fire protection certificate 30 Specific requirements iogas plants are complex process en- „ Operability of vital plant components in different gineering systems. A variety of pumps, weather conditions: The parts, components and compressors, agitators, screw conveyors equipment of the biogas plant relevant to safe op- and pipes are needed to transport sub- eration must be designed to remain operable at strate and produce gas. It must be possi- all times at the anticipated ambient temperatures B ble to ensure safe operation of all of these plant parts and in the expected weather conditions. and components at all times. Furthermore, the op- „ Sabotage / vandalism: System-relevant and safe- erator must provide the requisite quantities of work ty-relevant fittings and controls must be protected equipment, devices and materials, all in working against sabotage and vandalism. Lockable equip- order. Accordingly, the various parts and equipment ment can be used to ensure that this is the case, have to satisfy numerous requirements regarding the or fencing can be erected around the biogas plant protective measures that need to be taken. There are as appropriate. certain general requirements in terms of stability, vibration damping, operability, sabotage and vandal- The specific requirements for safe operation of the ism that apply to all parts of the plants: individual parts of the plant are described in the following section. Each description is divided into „ Stability: Parts of the biogas plant installed three parts: above-ground outdoors must be mounted on a sound foundation and protected against damage. They must be installed in such a way as to be eas- Technical protective measures ily accessible. Sufficient structural stability must be ensured. Organisational protective measures „ Vibration damping: Moving parts and parts sub- ject to vibration within the biogas plant (CHP unit components, blowers, pumps, compressors, etc.) Zoning according to the potential must be decoupled with compensators and vibra- explosion hazard tion dampers, for example. 1. Requirements for feeding systems Technical protective measures „ fixed grids with a rod spacing ≤ 20 cm „ self-closing flaps on vertical openings When choosing and designing the feeding systems „ wash-in channels in which vertical openings it is essential to pay attention to whether the materi- are covered als used are subject to particular stress or exposure (e.g. acids, sand etc.). It is strongly recommended If the digester is filled by means of a compacting that stainless steel or coatings should be used in screw, in consideration of all operating states it must particularly sensitive areas. Depending on the lo- be sufficiently immersed to prevent the possible es- cal climatic conditions, plant components at risk cape of gas. The immersion must correspond to at of freezing must be designed to be frost-proof. Me- least five times the response pressure of the overpres- chanical drives must be fitted with protective covers. sure protection device. If it is impossible to rule out Separators to remove interfering substances must the formation of hazardous gases outside the feeding be provided where necessary. Openings through system (CH4, CO2, H2S, NH3, H2 etc.) it is neces- which filling takes place, e.g. solids feeding equip- sary to prevent or reduce their release, for example ment, must be secured to prevent people falling in. through the use of appropriate filling equipment in Measures to prevent falling in include: a closed system or through spatial separation from other areas of the plant. Note the prevailing wind „ covered loading hoppers with a height direction when positioning filling openings so that of > 1.30 m in combination with a cover gases will be blown away from the operating area. If „ loading hoppers with no cover with a height feeding systems are installed inside buildings, they of ≥ 1.80 m must be equipped with ambient air monitoring and 31 Specific requirements ventilation. Liquid substrates must be fed in through hoses/pipes in such a way that no gases can escape into the building. Ventilation systems to/from the holding tank must end in a safe area via a closed line. Organisational protective measures The general principle is that the formation of hazard- ous gases outside the feeding system must be pre- vented if at all possible, or at least minimised, for ex- ample by preventing certain chemical reactions from taking place (filling at different times). Mixing of substrates outside closed tanks from which hazard- ous gases such as hydrogen sulphide, carbon dioxide or ammonia can be formed as a result of chemical reactions (for instance acid-base reactions) should be avoided. If reactions are to be expected as a result energie of feedstock materials being mixed before they are Mt ried out with harmless quantities of the substances fed into the digester, reaction tests should be car- photos: before mixing. Different feeding systems In order to be able to assess such reactions, op- yeast production, sodium sulphate as a preserving erators of biogas plants must obtain the following agent, adjuvants such as iron sulphate or catering details from the producers of their feedstocks and waste. document these in the operating diary: Feeders may need to be fitted with a control platform to ensure that the filling or flushing hose is safely Documentation of details of feedstock materials controlled. Attention must be drawn to the gas haz- ards in the immediate proximity of the feeder. If the „main constituents, chemical composition, pH occurrence of gases in hazardous concentrations in value and admixtures, e.g. stabilisers, preserving feeding areas cannot be ruled out, suitable gas warn- agents, etc. ing equipment must be installed to ensure that warn- „details of origin (e.g. from a slaughterhouse, from ing is given of gas hazards, in particular from H2S. the production of heparin in the pharmaceutical industry, etc.) In the course of their work on feeders, employees may „transport and delivery conditions (e.g., duration be exposed to biological agents through contact with of transport, temperature, ...) substrate, fermentation products or condensate or with impurities in pipes and gas-carrying plant parts. „potential hazards (e.g. ‘can release hydrogen The number of employees who are or may be exposed sulphide upon addition of acids’). If it is impos- to biological agents must be limited to those actually sible to rule out the formation of hazardous needed to perform the task in hand. Before carrying gases, especially H2S, it is necessary to prevent out work in the danger area of feeding systems, check or reduce their release, for example by means of whether the work is permitted to be performed alone. closed filling, spatial separation or forced removal In particular it is important to be certain of prevent- of the gases. ing the feeding systems from starting up automati- „other remarks cally during maintenance work. During the filling process, trace elements (e.g. nickel, Materials with a high sulphur content include wastes selenium) are often added to the feedstock. As a gen- from slaughterhouses, waste biomass (mycelium) eral rule the use of trace elements should be restrict- from biotechnological processes, rapeseed cake, ed to the necessary minimum. If the use of additives remnants of animal feed (e.g. soy protein), methio- and auxiliary materials is unavoidable, zero-emission nine from animal feed (feed additive), residues from or low-emission types must be chosen (e.g. pelleted 32 Specific requirements or coated products rather than powdered products), Classification of Ex zones and this must be documented. Appropriate measures must be taken to avoid the open handling of additives If a tubular screw conveyor system to feed input ma- and auxiliary materials. Employees’ exposure to ad- terials is installed below the surface of the liquid in ditives and auxiliary materials must be avoided or at the digester, the following requirements must be met: least reduced to the minimum achievable through „ limitation of the removal flow rate and daily technical and organisational measures. checking of the fill level, or The following types of work with additives and aux- „ if the fill level falls below a minimum limit, an iliary materials are most likely to present hazards: alarm is automatically triggered and removal is shut down so that the system remains safely 1. visual inspection of packaging for damage, below the level of the liquid. acceptance check No zoning necessary, unless the manufacturer’s 2. unloading from delivery vehicle, transport instructions specify different classification of within the plant, placing in storage zones. 3. removal from storage, making ready for use, putting to use In the case of liquid feeding systems (silage diluted 4. removal of impurities with liquid feedstock to make it pumpable) the pos- sibility of a hazardous potentially explosive atmos- 5. performance of maintenance work, e.g. phere being formed cannot be ruled out. Additional on the metering system explosion protection measures (ventilation, monitor- 6. disposal or return of packaging ing of CH4 concentration, etc.) are required in the vicinity of the feeder. 2. Requirements for substrate treatment systems The following substrate treatment methods may be used, depending on the process engineering needs: „ mechanical systems „ chemical systems „ biotechnological systems Technical protective measures Classification of Ex zones If rotating parts are used, they must be designed in → See Ex zone classification for holding such way that technical measures (e.g. a protective tanks / digester preliminary pits (see section 3) cover) prevent people from reaching in, being pulled in or falling in. Organisational protective measures Wherever mechanical systems are used, hazards caused by moving or flying parts and by the risk of falling in, especially during maintenance work, must be taken into account. Where chemical systems are used, for example additives and auxiliary materials, the relevant safety data sheets from the manufactur- ers and distributors must be heeded. When using substances that pose a risk to health (e.g. trace ele- ments), ensure that they are stored and metered in closed systems to minimise emissions. Preliminary pit 33 Specific requirements 3. Requirements for holding tanks/preliminary pits Technical protective measures surface of the substrate. Closed receptacles of this type also include receptacles with substrate Holding tanks/preliminary pits for substrates inside recirculation, substrate mixing and heating. buildings must be equipped with a suitable (e.g. No zoning necessary, unless the manufacturer’s explosion-protected) extraction unit with at least instructions specify different classification of five air changes per hour and flow monitoring with an zones. alarm in the event of failure. „ Interior of closed holding tanks / preliminary pits: Zone: same as the zone with the highest require- ments in the connected gas system. Organisational protective measures „ Vicinity of closed holding tanks / preliminary pits: No zoning necessary, unless the manufacturer’s The equipment for extracting the gases must be au- instructions specify different classification of tomatically switched on during the filling process. zones. Openings in the receiver tanks must remain closed „ Covered holding tanks / preliminary pits without except during the filling process. substrate recirculation and without heating outdoors: Non-technically leak-tight receptacle, not con- Satisfactory functioning of the extraction unit nected to the gas system. Has openings for filling. must be checked prior to commissioning and the No zoning necessary, unless the manufacturer’s results must be documented. instructions specify different classification of zones. „ Holding tanks / preliminary pits for easily Classification of Ex zones degradable substrates: Easily degradable feedstock materials include „ Holding tanks / preliminary pits: liquid and paste-like biowastes. An adequate Pit or tank, open or closed, for the receipt, buffer flow rate (e.g. at least five times air change of the storage and feeding of feedstock, in some cases pre-digester pit volume) is provided by monitored involving the mixing or recirculation of substrate extraction. or digestate, with or without heating. Zone 2: interior. No zoning necessary, unless the manufacturer’s No zone: exterior. instructions specify different classification of „ Holding tanks / preliminary pits for slurry with zones. maximum fill level below ground level: „ Open holding tanks / preliminary pits outdoors: A sufficiently large opening area, e.g. through Pit or tank for slurry, open across its entire cross- grating covers; very low gas production rate as section, with or without floating cover (no heat- a result of the low temperature. ing, no substrate recirculation and no digestate Zone 2: interior recirculation), gas accumulation not possible. No zone: exterior No zoning necessary, unless the manufacturer’s „ Insufficiently large opening area: instructions specify different classification of Air exchange takes place only during loading and zones. emptying processes. Very low gas production „ Closed holding tanks / preliminary pits outdoors: because of the low temperature. Pit or tank with a technically leak-tight cover; Zone 1: interior even slight leaks are detected at an early stage Zone 2: in the immediate area surrounding by regular checks; suitable gas displacement the openings with respect to the gas system in order to reliably prevent overpressure and underpressure; leak- tight feedstock input thanks to loading below the 34 Specific requirements 4. Requirements for the digester Technical protective measures Structural analysis of concrete containers must take account of the thermal stresses that are expected to arise depending on the planned insulation and the temperature of the substrate. In plants where leaks can arise above the level of the surrounding ground it has proved worthwhile to build a surrounding wall that retains the volume that could be released in the event of operational faults schMack until appropriate safety precautions take effect, and at least traps the volume of the largest tank. This photo: does not apply to storage facilities for solid digestion Interior of a digester prior to commissioning feedstock materials. The surrounding wall does not have to be completely closed; it can also take the form of a partial retaining wall if this sufficiently en- sures the retention of escaping materials. The base within the surrounding wall may consist of cohesive soil or paved areas, for example concrete and as- phalt. Access openings must have an inside diameter of windMeier at least DN 800 (according to ISO 6708) or have minimum dimensions of 600 x 800 mm. If it is nec- Jürgen essary to enter a tank for maintenance or repair work, it must be possible to provide adequate ventilation; photo: the same safety measures are also required when ac- An accident at a biogas plant cessing inspection chambers. These openings must be considered for the static concept of the digester. Every tank (including pre-digestion holding tanks/ Organisational protective measures preliminary pits) that holds gas, substrate or diges- tion products must be capable of being shut off from The visible parts of the tank must be regularly the rest of the system individually and in all direc- checked for leaks, and likewise the tightness of the tions. sight glasses. See section on inspections and tests for further details. In the digestion tank and secondary digester a fill Submersible-motor agitators and submersible- level monitoring system must ensure that the fill motor pumps must always be submersed when in level is not exceeded, for example by the digested operation. Appropriate operating instructions must substrates being fed to the liquid-manure pond via ensure that this is the case. a riser pipe (overflow) with frost protection or the maximum fill level of the tanks being limited with a suitable overfill protection device. Classification of Ex zones Particular attention must be paid to the operation of Interior of the digester tanks that have greatly fluctuating fill levels, such as The tank is constantly filled with gas and is operated secondary digesters or gas-tight end storage tanks, with positive pressure. If the pressure drops, there is for example with regard to explosion protection. a risk that atmospheric oxygen can enter the interior. Oxygen is prevented from entering the interior in the following ways: 35 Specific requirements „ Ensure gas production, e.g. by regular „ Ducts, technically leak-tight, in combination feedstock input with regular checks and maintenance, or the agitator penetration below the surface of the „ Ensure that the enclosure is leak-tight liquid/substrate. and stable No zoning necessary. „ Monitor the fill level of the substrate and if „ Ducts, technically leak-tight and above the necessary shut off withdrawal from the liquid surface of the liquid/substrate. phase (gas isolation point) Zone 2: 1 m around penetration. „ Ensure operation with positive pressure even in the event of a sudden drop in temperature, Overflow aid e.g. by means of i. suitable gas displacement with respect „ Overflow aid with screw conveyor. to the gas storage tank(s) Zone: as in downstream gas space. ii. constant monitoring of gas overpressure „ Pressure surge overflow aid with physical limita- in the interior and gas withdrawal tion of the injected air (volume limitation and iii. sufficiently variable volume of the gas flow rate limitation). storage tank Zone 0: in the pipe and in the vicinity of the overflow. „ In addition, where inflatable double layer roofs are used: ensure that the supporting air pres- „ Pressure surge overflow aid without physical sure is lower than the pressure in the gas storage limitation of the injected air. tank, and ensure that the inner membrane is Zone 0: in the pipe and in the digester. leak-tight and stable. Surroundings of sight glasses in inside spaces No zoning necessary, unless the manufacturer’s instructions specify different classification of „ Bull’s eyes and observation windows must be zones. fitted in a leak-tight mounting in the digester and permanently technically leak-tight accord- In the event that the above-mentioned requirements ing to manufacturer’s declaration. are in place without all measures to monitor and No zone. safeguard positive gas pressure being implemented, the following conditions apply: „ Sight glass technically leak-tight, routine leak checks in accordance with manufacturer’s „ The occurrence of potentially explosive atmos- instructions. pheres is identified, and measures are taken to No zone. ensure that such atmospheres occur only rarely and for short periods. „ Sight glass technically leak-tight, but no routine leak checks. Zone 2: above the surface of the substrate in the interior Zone 1: immediate vicinity. Zone 2: remaining area. Foreseeable disruptions or process-related operat- ing states that occur occasionally can allow air to Digestate storage with connection to gas system enter the interior of the digester, resulting in concen- Prevent air entering the gas system in the following trations falling below the UEL. ways: „ The occurrence of potentially explosive atmos- „ Ensure operation with positive pressure even pheres is occasionally possible. during removal of digestion products, e.g. by Zone 1: above the surface of the substrate in constant monitoring of gas overpressure in the the interior interior and shutting off gas extraction pipes and extraction points from the liquid phase; Agitators and ducts for agitator shafts and adjusters „ Planned, monitored removal of digestion prod- for agitators, e.g. cable mechanisms ucts, especially by Submersible-motor agitators and submersible- motor pumps should comply with degree of protec- Z ensuring gas supply, tion IP 68 according to DIN EN 60529. Material Z visual inspection for ethylene propylene diene requirements relating to corrosion, shear forces and monomer (EPDM) rubber membranes or gas thermal stability should be taken into account when fill level monitoring for double membrane selecting the agitators. systems or rigid gas storage tanks, 36 Specific requirements Z throttling the CHP unit, As operation with positive pressure during removal Z stopping removal of digestion products at of digestion products is not guaranteed in this case, minimum gas fill level; the following applies: „ Ensure technical tightness with the aid of initial and periodic checks, e.g. through location with a Zone 1: in the interior of the digestate storage tank gas camera and checking with foaming agents or and the interior of the connected gas system. a suitable gas detector; „ In the case of floating roofs, additional meas- ures; see section on gas storage tanks. In the interior, same zone as gas system. 5. Requirements for the gas storage tank Technical protective measures Gas storages must be gas-tight, pressure-tight and resistant to the medium, to ultraviolet light, tem- perature and weathering (storm, snow etc.) in ac- cordance with needs. With regard to wind and snow loads, in particular, it is essential that the manufac- turer produces a design that is site-specific. Gas storages must be connected via the gas-carrying adsolUtions system with overpressure and underpressure protec- tion device. Gas storage and their equipment must be protected photo: against mechanical damage. To prevent damage Lagoon digester in Costa Rica from vehicles in vulnerable areas, the gas storage and its equipment must be protected by (for ex- ample) collision impact protection guards, non- Especially in biogas plants operating according to traversable areas, barriers or observance of a safety the lagoon system, the large digester and gas storage distance. One means of meeting this requirement is surface areas pose additional demands on safety. to erect a safety fence around the gas storage. If the „ Both to protect the environment and for safety fence is less than 850 mm away from the gas stor- reasons, the link between the gas storage and age, the fence must prevent reaching through. The the lagoon digester should be technically leak- safety fence must take the form of a non-passable tight. Merely sealing the membranes by covering barrier, for example made of wire mesh, at least them with earth in the ground can be considered 1.50 m high. inadequate. The basic technically leak-tight at- tachment must be supplemented with regular Especially in the case of gas storages made of plas- organisational protective measures (checking for tic membranes, the following requirements must be digester/gas storage leaks by foaming, gas detec- met when selecting the materials: tors and infrared cameras). 500 N 250 N „ Tear strength min. 5 cm or tensile strength 5 cm „ Gas storage facilities connected to lagoon di- 1000 m3 gesters have a very large surface area and thus a „ Permeability with regard to methane < (m2 × d × bar) potentially higher risk of leaks (edge formation, „ Thermal stability for the specific application friction, tears etc.). All surfaces must be there- (mesophilic, thermophilic digestion process) fore checked for leaks at regular intervals (at least annually). Infrared cameras are useful for this „ Gas storages must be tested for leakage prior to purpose because then direct inspection of the commissioning membranes is not necessarily. 37 Specific requirements „ Because of the very large surface area there are „ Blower (no cross-flow through the interspace, additional dangers from wind exposure and the therefore occasional build-up of a concentration membranes being torn off. The gas storage should of diffusing biogas and sudden release when the therefore be fitted with additional safeguards to gas membrane is lifted or the blower stops) is prevent this from happening. possible. The build-up of concentrations at cer- tain times is prevented by breathing as a result of pressure fluctuations. Organisational protective measures Zone 0: in the interspace. Zone 1: 3 m around openings. The gas storage must be checked for technical tight- ness prior to commissioning, after being repaired Outer surroundings of the attachments of and at appropriate intervals. gas storage membranes outdoors „ The attachment is technically leak-tight combined with adequate organisational measures, and the at- The proper operation of gas storage systems tachment is regularly checked for technical tight- requires complete documentation and regular ness. The clamp connection is released only rarely. checks and maintenance work. Technical tightness over the long term is ensured in particular by seals appropriate to the pressure rating, the prevention of pressure loss in the clamp If maintenance and repair measures have to be per- hose connections, design resistance to precipita- formed on single-layer or double-layer biogas stor- tion and wind loads and organisational protective age membranes, they must not be stepped on. Any measures. Maximum pressure level p max = 5 mbar such loading (weight of an individual person) is only (5 hPa) (depending on attachment system). Biogas- permissible if proof of walk-on stability has been fur- resistant seals have to be implemented. Technical nished and a hazard assessment has been provided tightness is tested initially and periodically, e.g. by for the activities to be performed in the course of locating with a gas camera and subsequent check- the maintenance or repair. Within the framework of ing with foaming agents or a suitable gas detector. the hazard assessment, a particular focus must be No zone: exterior. placed on fall protection measures. „ As above, but the attachment is not only rarely released. Zone 2: 2 m around the attachment Classification of Ex zones Support air system Surroundings of single film systems The support air system includes the interspace, the „ Technical tightness combined with adequate support air inlet, support air outlet and the support organisational measures. Initial and periodic air blower. monitoring, e.g. locating with a gas camera and „ The support air outlet is monitored for a sudden checking with foaming agents or a suitable gas escape of gas by a suitable gas warning system detector. with an alarm and for a gradual escape of gas by No zone. a suitable gas detector. „ As above, but no adequate organisational Zone 2: inside the support air system and 3 m measures and without periodic checking. around air inlets and outlets. Zone 2: 3 m around gas storage and 2 m down- „ The support air outlet is monitored for a gradual wards at 45° escape of gas by a suitable gas detector. Zone 1: inside the support air system. Zone 2: 3 m around air inlets and outlets. 38 Specific requirements 6. Requirements for wooden roof structures in gas storage systems Wooden roof structures are often used as a sub- The aim is to detect damage at an early structure for gas storage systems. As wooden roof stage and prevent economic conse- structures in biogas storages are exposed to par- quences. ticular conditions, and visually indiscernible dam- „ Ad hoc check age to wood reduces the load-bearing capacity of Checking carried out in the course of the beams to such an extent that they are liable to opening of the tank for operational fail without notice, a special approach to checking reasons by the persons responsible structural stability must be used for the sake of the (operator, person appointed by the safety of all persons charged with inspection/main- operator or specialised firm): tenance work. Z A load test must be performed before anyone steps on the wooden Technical protective measures roof structure. Z The load test must be carried out Whenever wooden roof structures are used it is im- with a load calculated accord- portant to make sure that the structural analysis cal- ing to the formula below at at culations take account of the unusual environment, least three representative points water saturation and sulphur deposits. In order to in midspan (centre of a beam in guarantee the stability of the wooden structure, re- the longitudinal direction). If the inforcements must be installed between the beams. entire area is affected, testing of It is also necessary to choose suitable quality timber the roof structure must be carried that is precision-cut to size. out on at least every third beam and on particularly conspicuous gMBh The supporting construction of the timber beams must be designed such that the beams are prevent- or sagging beams. The test load must be applied for a period of at ÖkoBit ed from slipping out if they become deformed. least three minutes in midspan. photo: This can be done with a crane, for Wooden roof structure of a digester example. Organisational protective measures The method to be used for calculating the In order to ensure the stability of wooden roof struc- load needed to test the load-bearing capacity of the tures, regular visual inspections and checks must be timber beams is as follows: carried out during operation to identify any abnor- „ With cladding on the beams: malities. If the tank is opened for operational reasons, Area for loading a timber beam: a load test must be performed prior to walk-on access. R A = e× 2 (m2) e = spacing between beams Regular checks of timber roof structures R = radius in meters „ Regular visual inspection through sight glasses Test load (concentrated load in midspan) for the by the persons responsible (operator, person ap- 75 load test: P = A× 2 (kg) pointed by the operator or specialised firm) for: Minimum test load: 200 kg concentrated load Z conspicuous deformation, irregularities, per person, on each beam on which a person or breaks or splintering, for the purpose of ruling persons will walk. out acute apparent danger during subsequent „ Without cladding on the beams: investigative steps. In this case the load can be produced for exam- „ Regular checks regarding abnormalities in ple by a pallet with a water tank, operation by the persons responsible (operator, placed on supporting beams (12/12 cm). person appointed by the operator or specialised R Area for loading a timber beam: A = e× 2 (m2) firm) for: Test load (concentrated load in midspan) for the Z damage to or malfunctions in agitators, screw 75 load test: P = A× 2 (kg) Minimum test load: 200 kg concentrated load conveyors, etc. per person, on each beam on which a person or Z pieces of wood in pumps, coarse material persons will walk. screens or separators. 39 Specific requirements 7. Requirements for installation rooms for gas storages Technical protective measures Doors must open outwards and must be lockable. The safety distances as defined in the section on the Installation rooms for gas storages must have non- fire protection concept must be taken into account. closable air inlets and outlets that allow cross-venti- lation. Where natural ventilation is used, the air inlet must be positioned near the floor and the air outlet in Organisational protective measures the opposite wall near the ceiling. Clearance measurement is essential prior to work in hazardous areas. Written permission is required for work involving the use of an open flame. Classification of Ex zones The gas bag lies on the ground and is protected from the weather by a fixed housing. The housing is acces- sible all-round even when the bag is full. In inside spaces „ Constant ventilation of the space between the gas bag and the housing; flow monitoring and concentration monitoring; installation of a gas overpressure protection device and installation of a gas low pressure switch. Zone 2: Inside the housing and within 3 m of all openings to other rooms, and in the vicinity of openings to the open air with the exception of the gas overpressure protection devices. In the Gas storage facility interior, the same zone as the connected gas system. If a technical ventilation system is installed it must „ Natural ventilation of the space between the be ensured that the exhaust air is extracted from the gas bag and the housing; installation of a gas ceiling area. The exhaust air must be expelled direct- overpressure protection device and installation ly into the atmosphere. The forced ventilation system of a gas low pressure switch. must be dimensioned such that a maximum possible Zone 1: inside the housing gas volume is diluted to a maximum gas concentra- Zone 2: within 3 m of all openings. In the inte- tion of 20 % LEL in the installation room. rior, the same zone as the connected gas system. The air inlets and outlets must each have the follow- Outdoors ing minimum cross-sections: Zoning outdoors is essentially the same as in inside spaces. However, the effects of weather outdoors Gas storage volume Cross-section generally make it possible to define a zone with lower requirements than those for comparable situations up to 100 m³ 700 cm² indoors, or to reduce the extent of the zone. up to 200 m³ 1000 cm² over 200 m³ 2000 cm² 40 Specific requirements 8. Requirements for substrate-carrying parts of the biogas plant Technical protective measures Substrate-carrying pipes must be calculated and designed in accordance with the relevant technical Substrate-carrying pipes (including fittings, valves, rules. All forces and influences acting on the pipe- flanges, sealants and conveyor equipment) in biogas work (e.g. live loads, loads on connecting pipes, vi- plants must be leak-tight and adequately resistant bration stress, pressure surges, wind/snow) must be to the mechanical, chemical and thermal influences taken into account in the calculation and design of expected to arise with reference to the intended ser- substrate-carrying pipes, all pipe parts and support vice life. They must be longitudinally force-locked structures. Where possible, above-ground substrate- and frost-proof. carrying pipes must be routed outside traffic areas and marshalling areas; if this is not possible, they Pipes must be installed in such a way that their po- must be protected against mechanical damage with sition cannot be inadvertently altered. They must collision impact protection guards. not be used as carriers for other piping or loads and must not be attached to other piping. Detachable The pipes must be laid and installed in accordance joints and fittings must be installed as fixed points. with recognised standards of professional work- Suitable materials must always be used for pipes manship. Jointing work must always be performed (including fittings, valves, flanges, sealants and by specialists qualified for the respective material. conveyor equipment); their suitability and proper Prefabricated parts are to be used for connections fabrication must be verified and documented by the (to pipes and shafts/ducts). manufacturer in accordance with the relevant tech- nical rules. Pipes must be connected to buildings in such a way that subsidence, for example, does not adversely af- The material for each pipe must be chosen accord- fect the tightness of the joints. Wall bushings must ing to the chemical properties of the substrates flow- use pipe ducting systems that are tightly integrated ing through it (if applicable, take account of possible into the wall and secured to prevent being pushed changes of input materials), the operating tempera- out. The installation instructions provided by the ture and operating pressure. Depending on the area of manufacturers of the pipes and wall bushing sys- application, metal (steel, stainless steel) and/or ther- tems must be observed. Where necessary, pipes moplastic (PVC-U [not underground drainage pipe], must be secured to prevent being lifted out. If it PE, PP) materials come into consideration. Pipes is impossible to rule out maximum operating pres- must be protected against external corrosion or UV sure being exceeded, measures to prevent excessive radiation, as applicable, depending on the material pressure in the pipework must be taken. In order and installation location. Pipework must be planned, to prevent unintended discharge from a tank in the designed and installed such that it can be inspected event of the failure of a pipe connected to the tank and tested not only prior to commissioning but also below the level of the liquid, the pipe must be capa- periodically (take account of test pressure; make pro- ble of being shut off directly at the tank by means vision for all necessary shut-off devices for tests). of a gate valve. ! are essential whenever it is used, which means in at least 1,000 hPa (1 bar). TIP: PVC-U pipes responds to a maximum of only 500 hPa (0.5 bar)). PVC is not UV-resistant and its impact Pipes including all associated equipment and flex- strength is low. Proper storage and processing ible connections must have a structural rigidity of particular following the relevant instructions (for As a general rule, steel pipes are to be used. Plastic example manufacturer’s instructions) regarding in- pipes can be used outside enclosed spaces if laid stallation and processing. Proof must be provided below ground level in all cases and above ground that the installer has the requisite expertise. Cop- level as connecting pipes to a plastic-sheeting stor- per is not resistant to biogas; experience shows that age tank and as connecting pipes to the digester. brass and gunmetal are suitable (commercially Plastic pipes must be protected against mechani- available PVC underground drainage pipes are not cal and thermal damage and, if necessary, against permissible because their structural rigidity cor- UV radiation. 41 Specific requirements Organisational protective measures Gate valves, especially those on filling equipment, and other shut-off devices (inspection openings, but A piping layout plan (including the position and type also pumps) must be secured to prevent unauthor- of valves, fittings, connecting pipes and supports) ised opening. must be drawn up which shows the material and size of the pipework, the pipe run and the integration of The operator must regularly check all visible pipes the pipework in the biogas plant. for leaks by visual inspection and must document the inspection. 9. Requirements for gas-carrying parts of the biogas plant for hydraulic engineering installations such as di- gesters, condensate shafts or other structures. In gas pipes leading to consumption equipment such as heating boilers, gas flares and combined heat and power units, flame arresters must be fitted and operated as close as possible to the end-use equipment. Spigot-and-socket joints that are not in themselves longitudinally force-locked must be secured against thrust according to the pressures arising. The pipe connections must be longitudinally force-locked. schMack the case of wall bushings) must be prevented through Mechanical damage from settlement (for example in photo: the use of suitable bushings and appropriate con- Gas pipes (and labelling) nections. If the gas is wet, it is important to ensure the pipes are protected from frost. Condensate dis- charge pipes must be designed to be frost-proof and Technical protective measures operational at all times. Pipes connecting to the gas storage tank inside the gas storage tank’s installation Gas-carrying parts of the biogas plant must be pro- room are considered part of the gas storage tank. tected against chemical, weather-related and – in vulnerable areas – mechanical influences and dam- Two shut-off valves must be installed in the gas line age (e.g. collision impact protection guards in areas upstream of each engine unit. The valves must close where vehicles move). automatically when the engine stops. The interspace must be regularly checked for leaks. If the supply Gas-carrying pipes must conform to national require- line to the engine has a constant upstream pressure ments, with proof of proper manufacture, suitability (> 5 mbar) even when the engine is stopped, auto- for biogas and leak-tightness, for example by manu- matic interspace monitoring is required. facturer certification. Requirements arising from structural analysis (wind, snow load etc.) must be taken into consideration when selecting pipe materi- Organisational protective measures als and calculating spans. The installation instruc- tions provided by the manufacturers of the pipes and Pipes must be labelled to indicate the medium carried wall bushings must be observed when routing pipes and the direction of flow. When available, the relevant through buildings (e.g. gas and substrate pipes) and national guidelines should be followed in this regard. 42 Specific requirements The location of gas lines laid below ground must be Classification of Ex zones identified by gas pipeline warning tape. The suitabil- ity of flexible gas-carrying connecting pieces belong- Gas-carrying pipes ing to the CHP unit and the component parts of the „ Pipes carrying biogas (technically leak-tight); charge-air cooling system must be certified by the periodic inspection of plant parts for leaks. manufacturer of the CHP unit. Same zone as connected plant parts. Connection points in gas lines for non-stationary „ Pipes carrying biogas (technically leak-tight); facilities, such as mobile gas flares, must be fit- periodic inspection of plant parts for leaks, but ted with isolation valves. The shut-off valve must a potentially explosive atmosphere may occur be installed upstream of the non-stationary facility, in connected plant parts. The penetration of viewed in the direction of gas flow. It must be pos- potentially explosive atmospheres into the pipes sible to operate it safely. is prevented by automatic isolation from the con- nected gas system. Same zone as connected plant parts. 10. Requirements for condensate traps Technical protective measures Classification of Ex zones It must be possible to inspect and maintain conden- In inside spaces sate traps easily and safely, without having to climb „ Gas escape is prevented by the use of closed into shafts or pits. Permanently attached climbing drainage systems, e.g. locks with interlocked irons are not permissible unless the shaft of the double-shut-off valves; spaces with natural condensate trap has forced-air ventilation. Further- ventilation. more, access to these shafts is only permissible after No zone necessary. clearance measurement. „ If drain cocks are present, or open water seals, The design of the trap and maintenance measures it must be expected that a hazardous explosive must ensure that the escape of gas is prevented in all atmosphere will be formed as a consequence of operating states. Condensate discharge pipes must the water seals being punctured or drying out, or be designed to be frost-proof and operational at all because of an operating error. Discharge to en- times. closed spaces; space with technical ventilation. Zone 2: entire space Pressurised seal systems must be designed such „ If drain cocks are present, or open water seals, that the sealing liquid is unable to escape when the it must be expected that a hazardous explosive system is triggered but instead flows back automati- atmosphere will be formed as a consequence of cally. The filling level of the liquid seal corresponds the water seals being punctured or drying out, at least to a pressure of 15 hPa (150 mm water or because of an operating error. Discharge to column or 15 mbar) above the maximum response enclosed spaces; space with natural ventilation. pressure of safety devices and is monitored using Zone 1: entire space measuring instrumentation. Zone 2: 1 m around openings in closed space Organisational protective measures Outdoors „ Drain cocks outdoors, or pipes from condensate Requirements applicable to lone working must be separators installed indoors ending outdoors. taken into consideration (see section on protective Zone 1: 1 m around the outlet nozzle measures). Zone 2: a further 2 m around the outlet nozzle 43 Specific requirements 11. Requirements for overpressure and underpressure protection devices vented by technical and organisational measures. Breakdowns/damage caused by foaming must be prevented by the provision of for example a burst protection device, a pressure relief device or suf- ficient storage space. The suitability of the overpressure and underpres- sure protection device must be proven by a verifiable calculation and functional description. If designed to be immersed, the liquid tank must not be allowed to run empty, dry out or freeze. Liquid seals used as protection devices must be designed such that the sealing liquid flows back automatically in the event of overpressure or underpressure. The automatic closing of overpressure and underpressure protec- tion devices must also be guaranteed for mechanical energie and hydraulic systems. Mt : photo: of overpressure must be safely discharged either up- Any gas released as and when necessary in the event Overpressure and underpressure protection device on a digester wards or to the side. The discharge pipes from the overpressure and underpressure protection devices must lead to an end point at least 3 m above the Technical protective measures ground or the operating level and 1 m above the roof or the edge of the gas storage, or at least 5 m away Every gas-tight tank must be equipped with at least from buildings and public rights of way. one protection device to prevent the pressure rising above or falling below set limits. Any gas released as and when necessary must be safely discharged. A Organisational protective measures separate low pressure monitoring device in the gas system or an equivalent measure must be used to en- Overpressure and underpressure protection devices sure that the gas-consuming facilities or substrate/ must be inspected in accordance with the mainte- digestion product removal are safely forced to shut nance plans (see section on inspections and tests). down before the underpressure protection device is triggered, and that an alarm signal is issued. If over- pressure is present in the gas system (gas storages, Classification of Ex zones pipes etc.), as a rule an alternative gas-consuming facility (e.g. gas flare) should prevent the uncon- An Ex zone must be designated around the opening trolled release of biogas (see section requirements of the discharge pipe depending on the frequency for gas flares). There must be no means of shutting and duration of the occurrence of a potentially ex- off supply in the supply line to the overpressure and plosive atmosphere. underpressure protection device. Over and under- General requirements: pressure protection devices must be frost-proof. „ The outlet of the overpressure and underpressure protection device is at least 3 m above the con- It must be possible to inspect and maintain over- trol platform (inspection level) and 1 m above the pressure and underpressure protection devices eas- upper edge of the gas storage with a discharge ily and safely (stairs instead of a ladder). capacity of up to 250 m³/h; unhindered, safe outflow upwards or to the side. The overpressure Foaming of the substrate inside the digester or tank and underpressure protection device is checked is an operational fault and can have a detrimental regularly (daily) to ensure proper functioning. effect on the functionality of the overpressure and No zoning necessary. underpressure protection devices. This must be pre- 44 Specific requirements „ Restriction of overpressure and underpressure protection device response and limitation of emission by automatic gas fill level monitoring for operation with residual volume reserve or load-variable consumption, e.g. CHP unit with power reserve, and combustion by additional and constantly available gas-consuming facil- ity before the overpressure and underpressure protection device responds. protection device responds, but not all of these Zone 2: 3 m around discharge opening measures can be implemented: Zone 1: 1 m Zone 2: a further 2 m around discharge opening of overpressure protection device. 12. Requirements for gas purification Biogas is normally subjected to pre-cleaning prior Classification of Ex zones to utilisation. In addition to fine filters, this almost always involves the use of desulphurisation systems. „ Air supplied to the interior of the digester. Pipe bushings through the digester shell permanently 12.1. Internal desulphurisation through the supply technically leak-tight. Air infeed protected against of air to gas spaces in the digester backflow with spatially distributed input; volume of air max. < 6 % of volume of biogasnominal. Limitation of the volumetric flow of air is ensured Technical protective measures by technical means, e.g. maximum compressor capacity. If desulphurisation is carried out by supplying air Zone 0: only in the vicinity of the air infeed to gas spaces in the digester, the added air must openings and adjacent zone of the gas system. be spatially distributed and proportioned such that even if the flow control system malfunctions it is not possible to pump a total volumetric flow significantly 12.2. Internal desulphurisation through the more than 6 % of the biogas produced within the addition of iron compounds same time period. If desulphurisation is carried out by adding iron A backflow preventer (check valve) is required in the compounds (e.g. ferrous chloride) to the digester, supply line to the gas space, as close as possible to the manufacturer’s instructions must be followed as the gas space. There must be no other fittings apart per the data safety sheet. As iron compounds often from a shut-off device between the check valve and have a corrosive effect, the materials coming into the gas space. The space between the check valve contact with them should be resistant to them. and the metering pump must be depressurised to a safe area outdoors in the event of the pump stopping 12.3. Desulphurisation by means of ferrous if there is a danger of gas escaping into an indoor materials or activated carbon in external space. facilities Ferrous materials or activated carbon are often used Organisational protective measures for the external desulphurisation of biogas. These materials are capable of accumulating sulphur com- Regular checking of the oxygen content by measur- pounds. There is a risk of spontaneous heating when ing the volumetric flow of oxygen and plausibility these filter media are removed and regenerated. checking of the gas yield or regular measurement of the oxygen content using a gas analyser. 45 Specific requirements Technical protective measures Classification of Ex zones To be able to assess the functional capability of the Surroundings of external desulphurisation units activated carbon or other materials at all times, in- (outside digesters) cluding in ongoing operation, it is strongly recom- Outdoors mended that suitable monitoring systems (e.g. a gas analyser) should be installed. „ Desulphurisation system technically leak-tight. No zoning necessary, unless the manufacturer’s instructions specify different classification of Organisational protective measures zones. In inside spaces If the use of ferrous materials or activated carbon „ Desulphurisation system technically leak-tight. is unavoidable, zero-emission or low-emission types Zone 2: entire space must be chosen (e.g. pelleted or coated products rather than powdered products). 13. Requirements for gas analysis A variety of gas analysis systems are used in prac- Organisational protective measures tice, with a distinction being drawn between mobile and fixed systems and between manual and auto- Regular maintenance and calibration of the gas mated systems. The following gas constituents are analysis systems is recommended in accordance regularly detected: CH4, CO2, H2S and O2. with manufacturer’s instructions. Technical protective measures Classification of Ex zones The gas being measured must be discharged to the „ After gas analysis, the gas is discharged from the open air or returned to the gas stream. Alternatively, analyser to the open air. a forced ventilation system must be installed with a Zone 2: in the vicinity of the discharge opening. minimum air exchange rate that ensures adequate „ Technically leak-tight gas analyser in combina- dilution of the maximum possible gas volumes or tion with adequate organisational measures the gas facility must be relocated to the CHP unit in combination with regular leak checks and installation room. adequate ventilation in the room. No zoning necessary, unless the manufacturer’s instructions specify different classification of zones. 46 Specific requirements 14. Requirements for fittings and safety devices exposed to gas Biogas plants have various fittings and safety de- Organisational protective measures vices that are exposed to gas, including: „ Overpressure and underpressure Valves and fittings must be easily worked by an op- protection devices erator adopting a safe stance. Fittings used for gas withdrawal must be secured against unauthorised „ flame arrester and unintentional opening, for example by locking „ gate valve the handle. „ sampling tap „ shut-off valve The work instructions/operating instructions must „ dirt separator state that safety devices are to be checked after an operational disruption and at regular intervals in nor- „ etc. mal operation, taking account of the manufacturer’s instructions. Technical protective measures Fittings, safety devices and plant parts exposed to gas must be installed to be frost-proof in accord- ance with national guidelines and must be checked for leaks. They must also be sufficiently resistant to media, corrosion and pressure. 15. Requirements for gas flares In order to prevent climate-damaging methane from meet the general requirements for plant parts ex- being released, various national guidelines require posed to gas (in particular technically leak-tight, biogas plants to have alternative gas-consuming corrosion-resistant and frost-proof – including the facilities (thermal utilisation). Flare systems are condensate discharge pipe – in accordance with the often used for this purpose. There are different explosion protection requirements). Gas flares must types of flare, which can essentially be divided into be equipped with a flame ar- three categories: open flares; enclosed flame flares rester (DIN EN ISO 16852). (>850°C) and high-temperature enclosed flame This should be fitted as close flares (>1,000°C). as possible to the end-use equipment. Technical protective measures The heat resistance of the materials used must be taken Gas flare systems intended for use as alternative gas- into account, for which for ex- consuming facilities must be continuously ready for ample manufacturer’s notifi- operation and be capable of accepting the maximum cations or a type examination volume of biogas production. The gas flare system certificate must be presented. is usually driven by the fill level of the gas storage, The necessary minimum gas either pressure-controlled or via an external signal. supply pressure (flow pres- The length of the ignition intervals must be ensured sure) for the gas flare must be by approved control technology. Every gas flare sys- agreed between the manufac- tem must have a safety valve (slow opening/rapid turer and the operator for each closing, normally closed) that reliably prevents the gas flare system. Insufficient uncontrolled flow of air into the gas system of the gas supply pressure can lead biogas plant. The rapid closing function is executed to extinguishing of the flame, in less than one second. The gas flare system must especially if it is windy or in Gas flare 47 Specific requirements tional measures on the part of the operator), that the release of unburned biogas is safely avoided. Gas flare systems must be set up and positioned such that no persons are endangered by gases, flames or hot parts. The gas flare system should be erected in such a way that the flame is blown away from the gas storage tank, pressure relief devices, buildings and public rights of way when the wind is from the prevailing direction. The exhaust gases from the gas flare must be dis- charged above roof level with free outflow or via a discharge pipe that must be at least 5 meters away Gas flare from buildings and public rights of way and must end at least 3 meters above the ground. other special operating states (widely fluctuating gas storage fill levels). In automatic gas flare systems it is Organisational protective measures recommended that a minimum cut-in pressure of 10 hPa (0,01 bar) should be ensured. If it is not possible The gas flare should be checked for technical tight- to achieve sufficient gas supply pressure upstream of ness and for proper functioning of its safety and the gas flare system, appropriate equipment to rec- monitoring equipment at regular intervals. The tify this must be provided (e.g. gas pressure booster manufacturer’s instructions for commissioning, op- blower, pressure-maintaining valve). eration and maintenance should be followed. For emergencies and maintenance work outdoors the gas supply to gas flare systems must be capable of Classification of Ex zones being shut off manually as close as possible to the installation location of the consumption equipment. „ The escape of gas to the surrounding area if the The open and closed positions must be identifiable flame is not burning is prevented by an automat- or labelled. ic shut-off device coupled with an automatically actuated ignition device and flame monitoring It must be possible to operate gas flare systems suf- (auto ignitor). A suitable flame arrester is fitted ficiently reliably, for example independently of power in the gas line upstream of the flare. supply from the electricity grid (off-grid e.g. by bat- No zone necessary. tery, emergency power supply or by other organisa- 16. Requirements for process control system / instrumentation and control (I&C) system Technical protective measures switch, the plant or the relevant parts of the plant must switch to a safe state. The safe state can be Control systems with safety functions must be de- achieved by means of control engineering measures, signed to be fail-safe, unless they are backed up by hydraulic measures or mechanical measures. a redundant system, for example a mechanical over- pressure protection device to protect against over- Examples: pressure or an overflow to protect against overfilling. „ Closing of automatic gas valves outside the CHP unit installation room In the event of failure of the auxiliary power (electrici- „ Switching off relevant gas compressors ty, hydraulic or pneumatic supply to the biogas plant), a safety shut-down or actuation of the emergency stop „ Disconnecting all non-explosion-protected parts 48 Specific requirements in installation rooms exposed to gas (CHP unit, The latest applicable standard for electrical equip- gas purification, etc.) ment of machines and the equivalent for safety-re- lated parts of control systems must be used for the „ Closing of gate valves so that substrate cannot design of safety-related parts of the control system. flow back into the feed system (e.g. pre-digester A hazard and risk analysis must be performed in ac- pit, animal shed) cordance with national guidelines. „ External feed facilities must be capable of being shut off in the event of system breakdown to prevent overfilling Organisational protective measures „ A drop in the fill level must not lead to an uncon- trolled escape of gas, for example from the feed The requirements for safe functioning of instrumen- system tation and control (I&C) equipment with a safety function must be established, determined and doc- umented on the basis of a hazard assessment. 17. Requirements for electrical engineering 17.1. Equipotential bonding „ Dangerous accumulations of electrically conduc- The relevant national regulations apply to all electri- tive dusts in or on electrical equipment must cal installations and switchgear. be avoided, for example by means of enhanced dustproofness for the equipment. In order to prevent the creation of potential differ- „ Suitable measures must be taken to prevent the ences, all electrically conductive plant parts must entry of ignition sources into hazardous areas be connected to each other and to the protective via cables and leads. Cables and leads should conductor and the potential equalisation. be laid without interruptions in hazardous areas. If this is not possible, the connections must be ! cian prior to commissioning and at regular TIP made in enclosures with a protection type ap- It is always advisable to have the electrical propriate to the zone or they must be secured by installations checked by a qualified electri- means of appropriate junction boxes. „ Discharges of static electricity must be avoided intervals. For details refer to the section on if they are capable of being effective ignition inspections and tests. sources. „ High charge-generating processes give rise to such high charge levels that spontaneous Technical protective measures ignition-inducing discharges may occur. The use of objects or equipment made of insulating The following protective measures must be taken in materials in hazardous areas should be avoided. order to prevent potential differences: If objects or equipment made of conductive or „ Cable entries and glands must be suitable for the dissipative materials cannot be used, measures respective ignition protection types. In addition, must be taken to prevent dangerous charging. electrical installations must be designed and electrical equipment assembled and installed so „ Electric cables and leads must be laid separately ! in textiles, limitation of surface areas or reliably as to ensure easy access for inspection, testing TIP and maintenance. Possible measures include conductive or dissipative coatings, conductive threads from pipes, with the exception of electric trace effective organisational measures. heating systems. Electrical installations must be designed to restrict the effects of electromag- netic fields to a safe level. 49 Specific requirements Organisational protective measures with the plant control system using a simple instal- lation without a PLC and frequency converters (e.g. The plant operator must ensure that the only persons operation only with plug connector and motor pro- to have access to the hazard area of electrical in- tection). stallations are those who on account of their profes- sional training, knowledge and experience are able In relatively large biogas plants with several parts to recognise the electrical hazards arising and take to the plant (such as gas processing systems) the the necessary occupational health and safety meas- gas flare systems are not necessarily controlled by ures, and that other persons are permitted to enter and supplied from the biogas plant. In such cases it the hazard area only when accompanied by persons should be examined how the gas flare system can be as described above. put into operation by ‘simple’ means in the event of a complete power failure. The plant operator must also ensure that all electri- cal installations and equipment used are suitable for In order to be able to guarantee a reliable supply of use under exposure to the stresses and loading from power it is also highly important to determine the the operating conditions and environmental condi- power required to maintain the essential processes. tions at the workplace. This includes: 17.2. Protective measures in the event of „ Defining all processes that need to continue a power outage running in the event of a power failure „ Establishing the length of time for which the As part of a hazard assessment it is important to defined processes need to continue running in produce as comprehensive a list of potential haz- order to prevent any danger from arising ards as possible for each biogas plant individually „ Determining the power demand that needs to be and to determine the necessary protective measures met by an uninterruptible power supply (UPS): deriving from that for each specific situation. In the following the focus is set on the hazards arising and Z information technology necessary countermeasures to be taken in the event Z alarm systems of failure of the public power grid. Z telecommunications Z safety lighting, etc. Technical protective measures „ Determining the total amount of power needed to maintain operationally critical processes: In order to be able to guarantee an emergency power Z information technology (all of the above) supply for the biogas plant the first requirement is Z system control fault-tolerant installation (e.g. safe from floodwater Z agitators or from substrate if it escapes inside the surround- ing wall). Z gas-consuming equipment (if applicable including compressor) In addition, the electrical installation of the biogas Z lighting plant must be checked for ‘quick-action’ activation of the agitators and other important components. Choosing the correct emergency power strategy is In this regard consideration should also be given to also important. Various options are presented in power failures caused by thunderstorms, for exam- Table 6. ple: if important components such as the program- mable logic controller (PLC), frequency converter, 24-volt power supply units or emergency stop re- lays cannot be started quickly, further precautionary measures must be taken. Ideally, agitators or other important components can be started in parallel 50 Specific requirements Table 6: Advantages and disadvantages of various emergency power strategies Advantages Disadvantages Fixed emergency power „ Availability „ Regular maintenance required unit with own fuel store Possibility of automatic start-up „ Fewer possibilities of error in commissioning Mobile emergency „ Can also be used for „ Generally smaller than fixed units power unit with own other purposes for short (!) „ Requires basic electrical knowledge (needs a larger number of manual stock of fuel periods switching procedures) „ Greater workload involved in setting up in an emergency compared with a fixed emergency power unit (obtaining the unit and connecting cables to the biogas plant) Mobile emergency „ High level of availability „ Requires even more basic electrical knowledge (rotating field? max. avail- power unit driven by „ Lower cost able output? equipotential bonding? power system stability, etc.) and needs tractor (PTO shaft a larger number of manual switching procedures connection) „ Even greater workload involved in setting up in an emergency than with a mobile emergency power unit (obtaining the unit, cables and tractor) „ Tractor must match the unit (correct PTO shaft, correct rotational speed, sufficient output) Organisational protective measures Inspection and maintenance plans must be regu- larly updated. It is also important to check regularly A number of additional organisational measures whether the design of the emergency power unit must be taken into account in order to safeguard and uninterruptible power supply (UPS) meet the emergency power supply. current capacity and quality requirements. Further- more, regular checks/functional tests of the fuel are Drafting of an emergency plan for power failure required. comprising: The fuel quality of diesel in particular is liable to di- „ organisation chart (organisational structure) minish on account of weather conditions and ageing. „ determination of responsibilities and account- abilities including telephone numbers, in It is likewise very important to compile a set of oper- particular arrangements for on-call service and ating instructions with a comprehensive description its tasks and powers of operation and maintenance (including plans for „ task description operation under emergency power and exercises). During emergency operation it is necessary to check „ alarm levels and decision-making channels whether all intended loads are receiving power (us- (organisational procedures) ing a prepared checklist; including telephone con- „ determination of which workplaces can be used nection). For this purpose, an individual should be and which workplaces are exposed to risks (e.g. nominated (if applicable an operational safety of- overpressure and underpressure safety device). ficer) who is responsible for operation and mainte- nance of the emergency power supply system. In addition, employees must be given regular in- struction and briefings, with written proof, and hold The holding location should be specified and se- exercises covering specific dangerous situations. cured. Access to mobile emergency power units The experience gained in these should be incorpo- must be possible without hindrance. When the unit rated into the emergency strategy. is put into service, a trained electrician must be pre- sent for an initial trial in isolated operation or an 51 Specific requirements emergency power exercise. The emergency power „ ensure that in emergency operation each con- unit must be properly earthed in order to prevent the nected user is able to draw at least the minimum tripping of residual-current-operated circuit break- amount of energy from the emergency power ers. The labelling of the switchgear cabinet must be supply defined in advance; easily comprehensible. „ make technical provisions to ensure that in emergency operation each connected user If the emergency power unit is potentially used for is able to draw only the maximum amount of more than one business/type of business: energy from the emergency power supply defined in advance. 18. Requirements for lightning protection The matter of lightning protection at biogas plants and telecommunications. Experience to date sug- must be managed in accordance with national reg- gests that external lightning protection (intercepting ulations and the regional risk of lightning strikes. devices, arrester equipment, earthing system etc.) is There is a basic distinction between external and not generally necessary. internal lightning protection. Internal lightning pro- tection serves to prevent surge damage within the installation. External lightning protection by means Organisational protective measures of lightning rods serves to divert lightning strikes that would hit the protected installation directly. The matter of lightning protection should be taken into consideration in the hazard assessment carried out for the construction and operation of the biogas Technical protective measures plant. Biogas plants should have at least internal lightning protection. A surge arrester (internal lightning pro- Further information concerning tection) and consistent equipotential bonding are lightning protection can be found therefore required for the electrical installation and within the norm DIN EN 62305. the facilities for electronic control, data processing 19. Requirements for rooms with substrate-carrying and / or gas-carrying plant parts Rooms with substrate-carrying and/or gas-carrying Requirements for CHP unit installation rooms plant parts include the CHP unit installation room, If it is not possible to ensure that all gas-carrying pump room, etc. plant parts in CHP unit installation rooms are per- manently technically leak-tight, sources of ignition must be avoided and if applicable explosion protec- Technical protective measures tion zones must be designated. Explosion protection zones in installation rooms can be restricted or avoid- General requirements ed by taking additional measures, such as a forced As a general rule, maintenance and control stations ventilation system with monitoring of the air flow or a and the controls of valves, agitation, pumping and gas warning device coupled with ventilation. flushing equipment should always be situated above ground level. If this is not possible, adequate techni- Depending on the nature of the gas, the detecting el- cal ventilation must be provided with at least five air ement of the gas warning device should be mounted changes per hour. above or in the vicinity of possible sources of re- leased gas, taking into account the effects of the 52 Specific requirements ventilation system in its various possible operating The CHP unit must be mounted on its foundations states. The evaluation units must be installed out- and installed such that the unit’s vibrational load is side the room being monitored. below the vibration levels permissible for continuous operation. The forced ventilation system must be dimensioned such that a maximum possible gas volume is diluted For further information to a maximum gas concentration of 20 % LEL in the about installation rooms, refer to installation room. DIN ISO 10816-6. At an alarm threshold of 20 % LEL (0.9 % v / v CH4) in the room air, the response should be visual and Floor drains must have oil traps. Alternatively, a col- audible warnings and air intake or extraction at lection tank to catch the entire volume of oil must be 100 % power. positioned beneath the engine. At for example 40 % LEL (1.8 % v / v CH4) in the It must be possible to shut down the CHP unit at room air, the response should be visual and audible any time by means of an illuminated switch out- warnings, air intake or extraction at 100 % power side the installation room. The switch must have and automatic shut-off of gas supply outside the in- a clearly visible, durable label ‘Emergency Stop stallation room. Switch – CHP Unit’ and must be accessible. The same requirements also apply to electrically oper- The gas warning device continues to operate after ated shut-off valves. the second alarm threshold is exceeded, i.e. it is not switched off. Two shut-off valves must be installed in the gas line upstream of each engine unit. The valves must close If a technical ventilation system is installed it must automatically when the engine stops. The interspace be ensured that the exhaust air is extracted from must be regularly checked for leaks. If the supply the ceiling area. The exhaust air must be expelled line to the engine has a constant upstream pressure directly into the atmosphere. > 5 mbar (5 hPa) even when the engine is stopped, automatic interspace monitoring is required. ! rooms is obtained from the following equation: TIP Doors must open outwards and must be lockable. The minimum free cross-section ‘A’ of the air inlet/air outlet of CHP unit installation Organisational protective measures A = 10P+175A = free crosssection (cm2) P = maximum declared electrical output from The gas warning device must be maintained in ac- the generator, kWel cordance with the manufacturer’s instructions. Gas warning systems must be tested regularly, at least Examples: once a year. Operating instructions must be drawn 22 kWel = 395 cm² and 30 kWel = 475 cm² up for cases where the alarm is triggered by the gas warning device or a fault in the gas warning device. Further requirements for CHP unit installation rooms: Classification of Ex zones CHP unit installation rooms must be dimensioned such that the combined heat and power units can be Technically leak-tight gas-carrying plant parts com- properly installed, operated and maintained. This is bined with adequate organisational measures, peri- generally the case if the CHP units are accessible odic inspection for leaks. Monitoring of the installa- on three sides. Doors must open in the direction of tion room for potentially explosive atmospheres: e.g. escape. If CHP units are operated inside containers, at 20 % of LEL triggering of alarm and maximisation later replacement should be possible without diffi- of fan output (at least five air changes per hour), at culty. The air flow parameters prescribed by the CHP 40 % of LEL automatic shut-off of gas supply. unit manufacturer should be reliably achievable in the CHP unit installation room. No zoning necessary 53 Inspections and tests I n order to make plant operation lastingly safe, Table 7: Minimum inspections and tests both initial and various periodically recurring in- recommended by the German Biogas Association spections and tests must be carried out for the entire plant, parts of the plant and the docu- Test object Test frequency mentation. Fire extinguishers Every 2 years The inspections and tests can be divided into the following separate segments: Safety equipment At least once a year (e.g. gas warning „ structural safety equipment, venti- „ explosion protection lation systems and inerting equipment) „ pressurised systems Apparatus, Every 3 years „ electrical installations protection systems „ water resources protection and safety systems „ pollution control Explosion protection Prior to commissioning „ functional safety testing (general) and periodically at least every 6 years „ fire protection „ business organisation Inspection for Prior to commissioning, compliance with then every 5 years, in The inspections and tests must be performed by water legislation water protection areas specially trained experts or by persons qualified to every 2.5 years conduct inspections and tests. In addition to the Safety-related Prior to commissioning, necessary training and specific knowledge (includ- testing then every 3 or every ing professional experience in the field of biogas), the 5 years (depending on inspectors must have at their disposal the requisite approval) test and inspection equipment. Proof of compliance Electrical testing Every 4 years with these requirements should be provided. of switchgear / ‘E-Check’ inspection With due regard for the respective national require- ments, the following types of inspection and testing Pressure vessels External inspection every are recommended for biogas plants: 2 years, internal inspection every 5 years and strength 1. Document inspection: checks to ensure that the test every 10 years documentation is complete, correct and up-to- date. The results of the inspections and tests are to be 2. Visual inspection and functional test: checks documented in a test report, which must include at to ensure that the technical and organisational least the following information: safety precautions are complete, correct and in 1. Identification of the plant proper working order. 2. Date of inspection or test 3. Type of inspection or test ! it makes sense to draw up an inspection and TIP 4. Basis for the inspection or test Given the large number of different periodically recurring inspections and tests 5. Scope of the inspection or test 6. Effectiveness and function of the test plan showing all the necessary inspections protective measures taken and tests and the contact details of the inspec- tor / test engineer required in each case. 7. Result of the test and date of the next periodically recurring test 8. Records and test certificates must be kept at the The German Biogas Association considers the follow- site of the plant being monitored for the entire ing on-site inspections and tests on biogas plants to duration of use of the plant. In addition, it is be the minimum required (see Table 7). advisable to keep a copy at a different location. 54 Upgrading of biogas to biomethane he raw biogas produced in the plant is sub- jected to basic cleaning prior to utilisation in the CHP unit (see figure 13) . This gen- erally consists of dewatering (drying), H2S reduction and the removal of suspended T solids. However, if biogas is intended to be used as a substitute for natural gas, as a fuel or in compressed form in pressure cylinders, further upgrading of the gas is required, which mainly comprises the sepa- ration of methane and carbon dioxide and the fur- ther reduction of undesirable gaseous constituents (H2S, NH3 and other trace gases). Biogas upgrading requires an additional technical facility, the safety aspects of which are explained in the following. As raw biogas is a mixture of various desirable and undesirable constituents, basic cleaning and fine cleaning are required. Basic cleaning of the raw biogas usually takes place at the biogas generating plant (digester), and fine cleaning or purification at the biogas upgrading plant. In order to adapt the upgraded biogas (biomethane) to the quality stand- Biogas upgrading unit ards of the natural gas grid and/or the requirements of natural gas consumers (natural-gas vehicle, gas burner, CHP unit etc.), further conditioning (for ex- Depending on the respective national requirements ample adjustment of the methane content and calo- (laws, ordinances and sets of regulations), different rific value etc.) should be carried out, depending parts of the biogas upgrading plant may have dif- on national regulations. This treatment takes place ferent operators and may be subject to stakeholders in biogas conditioning plants. Before the upgraded with different areas of competence: the biogas plant biomethane is injected into the specified natural operator, gas supplier/gas grid operator and/or the gas grid, further steps are required: pressure adjust- competent authorities. Responsibilities in the vari- ment, pressure protection, gas metering and if nec- ous parts of the plant should be defined according essary odorisation. to these areas of competence, and set out in writing. Figure 13: Process flow chart for a biomethane upgrading and injection plant electric grid Biogas plant CHP gas flare LPG exhaust air grid raw biogas upgrading conditioning injection gas cleaning unit natural digester Upgrading and injection plant 55 Upgrading of biogas to biomethane The relevant qualifications held by the responsible quality, corrosive constituents of the gas, internal operators and the personnel assigned to the work pressure, climate, geographical location). Potential must also meet national requirements. The same deformation, deflection and linear expansion must applies to specialised companies involved in the be taken into consideration when installing the planning, construction, operation and maintenance pipes, in accordance with site-specific regulations. If of the plants. Regular training measures should be it is expected that condensate will be formed (mainly obligatory in order to keep technical knowledge up- applicable to biogas pipes), the pipes should be laid to-date with the latest findings and technical require- on a gradient and fitted with condensate separators ments. For organisational reasons it is advisable to at the low points of the installation. draw up a plan of the organisational structure for the plant as a whole. It is particularly important that building entry points for gas pipes are corrosion-resistant and strain-free. In addition, a plan of organisational procedures Pipes carrying gas must always have corrosion pro- should be drawn up (recording of faults: checking, tection, ignition protection and equipotential bond- causes etc.) along with operational documentation ing, and they must be clearly identified by colour- (briefings, inspections, tests, incidents, work in- coding or labelling. structions etc.). If gas pipes are potentially exposed to mechanical To be documented: damage (for example from vehicles or other traffic), „briefings and instruction sessions held they must be protected accordingly by collision im- pact protection guards. If gas pipes are laid on land „inspections and tests belonging to a third party or public property, permis- „incidents sions/concessions for crossing the land (e.g. roads „work instructions and railway lines) and laying the pipes must be taken into consideration. Technical protective measures Gas pipes must be checked to ensure they are in faultless condition prior to installation. National The odorisation (addition of an odorous substance as guidelines regarding pipe covering, pipe routing and a warning) of natural gas/biomethane is an important filling of the pipe trench (e.g. in sloping locations) safety measure because purified natural gas/biometh- must be observed. ane is almost odourless. In order to ensure that leaks in pipes or parts of the indoor gas installations are no- Gas pipes must be subjected to a pressure test after in- ticed promptly, for safety reasons specific prescribed itial installation and after any significant changes, with warning odours are added to the natural gas/biom- due consideration for the relevant regulations (test ethane. The smell of the odorised gas must therefore procedure, test duration, test medium, test pressure, not be familiar to people from their everyday lives, for person permitted to perform the test etc.). If the op- example from kitchens or a domestic setting. erating pressure changes during use, any regulations relevant in such circumstances must be observed. The upgraded biomethane must be adapted in ac- cordance with the odorisation requirements of the Documentation for pipes: gas grid into which it is to be injected. This usually involves the use of highly volatile, typical-smelling „details of the design of the gas pipes organic sulphur compounds such as tetrahydrothio- (pressure, nominal diameter ...) phene (THT), which smells like rotten eggs, and mer- „structural analysis records captan mixtures. „certificate of competence from the executing companies National regulations must be observed in the plan- „up-to-date working drawings and ning, construction and maintenance of pipework in plans of present inventory of facili- biomethane plants and external areas, and in the se- ties and equipment lection of materials. All such work must always be carried out by specially trained personnel. „pipe book (documentation of weld- ing work, verification of quality The choice of plant components should be made ac- requirements) cording to practical requirements at the plant (gas „test reports / acceptance certificate 56 Upgrading of biogas to biomethane When work is carried out on the gas installation it must be safely depressurised to the open air and Before any maintenance work is carried out, an must be inerted. A clearance measurement should individual hazard assessment is required, with be carried out prior to work on the gas installation specified protective measures. This must be in order to rule out hazardous Ex zones. Following agreed with all plant operators (biogas production, maintenance / repair work and prior to resumption of cleaning, conditioning and injection). operation, the relevant unit should be subjected to a leak test and functional test. The necessary tests must be performed by qualified professionals and All persons assigned to perform maintenance work must be documented. If necessary, oxygen contained on the installations must be qualified, approved and in the gas system must be removed and the system reliable and must have received special instruction. must be flushed with process gas prior to resumption This applies both to the plant’s own staff and to ex- of operation. The resumption of operation must be ternal companies and workers. German regulations agreed and coordinated with the persons responsible require, for example, that certain activities, namely for the upstream and downstream parts of the plant. functional testing, maintenance, repair and resump- tion of operation, must always be performed by two Only approved specialised companies/skilled work- persons, at least one of whom must have the neces- ers are permitted to perform welding work on pipes sary expertise and the other must at least have re- and gas-carrying systems. Detailed descriptions of ceived relevant instruction. equipment, devices, procedure testing, performance of the welding work and testing of the weld are given Maintenance and repair work should be systemati- in national regulations (in Germany: DVGW GW 350 cally prepared. This means that necessary protective and G472). Welding work on gas-carrying plant parts equipment (e.g. respiratory protection, warning de- is not permitted in installation rooms (exceptions vices, fire extinguishers etc.) must be made availa- may be possible if justified). ble. It is also advisable to draw up a work programme and overview plan in which all relevant activities and The relevant national regulations must be observed plant components are plainly apparent. Where nec- when work is carried out on pressurised plant parts. essary, automated processes in the system should be switched to manual operation before maintenance or repair work is carried out. Organisational protective measures An individual person must be named as being re- sponsible for safe operation and the safety of the If condensate is expected to arise, the pipes and plant, and be granted the necessary powers. To avert condensate discharge systems must be regularly danger, an on-call service must be arranged at the maintained and cleaned. Pipes above ground lev- plant itself or through an external service provider el must be checked for leaks on an annual basis. so that constant standby backup service is ensured Shorter intervals should be planned for compensa- (24 h/7 days). In Germany, for example, the on-call tors and other specialised components where neces- service must be present at the plant within max. 30 sary (hazard assessment). Every two years pipes laid minutes in order to be able to respond to faults in above ground (including pipe protection) should be good time. checked to ensure that they are in good condition and for external corrosion. If necessary, the UV pro- Instrumentation and control (I&C) systems must be tection of plastic pipes should be repaired. checked by a qualified professional at least once a Biomethane plants and their components must be year and after each maintenance operation to ensure maintained and serviced in accordance with the that they are in working order. The operator of the manufacturer’s instructions (method, intervals plant must draw up a test plan for this purpose. etc.). Essentially a distinction is drawn between three types of maintenance: All tests, measurement reports etc. must be docu- mented in writing or electronically and kept as long „ planned maintenance (fixed intervals) as necessary (at least two maintenance intervals). „ condition-based maintenance (after assessment Structural changes at the plant must be document- of the state of the plant) ed. Other tests must be performed in accordance „ corrective maintenance (initiated because a with the general test requirements for biogas plants fault has arisen) (electrical safety, explosion protection etc.). 57 Recommendations for safe plant operation s biogas is covered by very different ar- operated safely these days. In other countries this is eas of law (agriculture, waste manage- not the case; all too often, the principle tends to be ment, energy industry, health and safety ‘life is cheap’. The people responsible are not con- at work etc.) and is a relatively young sistently held to account. These differences in safety technology, in many countries there are culture are a crucial factor in the safe operation of A no biogas-specific competencies or laws, ordinances plants. Efforts to establish and implement regula- or regulations. The same is true in particular for the tions on safe biogas operation should be pursued as field of international standardisation. Initial efforts rigorously as possible in all countries. are being made to develop an internationally coordi- nated set of rules and standards on biogas (ISO TC One highly significant element of the legal frame- 255 ‘Standardisation in the field of biogas’). work that is meant to guarantee safe biogas opera- tion is the issue of responsibility. In many countries when accidents occur there is a very thorough in- vestigation of what caused the accident and who is responsible for it. If the accident is serious, the po- lice, expert appraisers, the fire brigade, employers’ liability insurance association or other institutions are usually involved in the investigation. The ques- tion of who is financially liable for the damage is also relevant to insurance companies. If rules and raMspott may be subject to severe penalties (financial or even regulations have been ignored, those responsible imprisonment). istock_frank : Unfortunately, in many countries the matter of re- sponsibility is not defined, or the rules and regula- tions are not consistently applied. One quite crucial illUstration: recommendation is therefore that in every country where industrial biogas plants are operated it is es- sential to define who is responsible in the event of an accident. These rules must be rigorously enforced. Established and recognised industry associations have a crucial role to play in agreeing, develop- It is usually the case that the operator of biogas ing, introducing and implementing safety-specific plants bears a high degree of responsibility. He is standards. The interests and needs of the stake- responsible for safe operation of the plant and is holder groups in the biogas industry can thus be generally personally liable. If construction work has pooled to best effect and the maximum degree of been executed poorly, approval has been granted in- acceptance established. The German Biogas Asso- admissibly or other rules and regulations have been ciation, for example, has conducted debates on the breached, other companies or institutions may also subject of safety within its own working group on be responsible. safety ever since the foundation of the association, and has issued recommendations accordingly. The working group is made up of experts working in an honorary capacity from various safety-related fields of the biogas industry. The working group supports the German Biogas Association and its members in dealing with questions and problems. In the international context there are very different ways of dealing with the consequences of accidents. In some countries every accident, however minor, is registered and taken seriously, and the causes are retraced in order to avoid accidents in future if at all possible. In these countries biogas plants are mostly 58 Recommendations for safe plant operation 1. Recommendations for the legal framework „ In order to prevent overlaps in relation to safety- „ In order to ensure the safe operation of biogas related issues and areas of competence, ideally plants it is advisable to consider introducing an the subject of safety at biogas plants should be expert appraiser system for biogas plants to ex- dealt with by just one ministry and its associated amine the licensing of biogas plants and to be authorities and agencies. able to supervise the planning, construction and operation of biogas plants at the time of commis- „ In Germany, all aspects of the law concerning sioning and at periodic intervals. The experience construction, waste management, the environ- gained from the appraisals should be collected ment and occupational and industrial health and and analysed. The findings can then form the ba- safety that are relevant to the construction and sis for any adjustments that need to be made in operation of a biogas plant are examined as part the regulatory framework. of the licensing process for biogas plants. In many countries, however, there is no legal instrument „ Experience from cases of damage or accidents that provides for similarly comprehensive inspec- should be recorded and then evaluated on the tion and regulatory approval. basis of uniform criteria. The results can also provide useful information in finding solutions to „ If structures are set up in the new biogas mar- problems and opportunities for optimisation. The kets that establish comprehensive or even biogas latest findings and insights from the biogas indus- plant-specific licensing procedures, it would be try should be made easily accessible in regular particularly important to include safety-related publications and technical information sheets and functional aspects (such as expert planning, and at conferences. design of the plant, choice of components etc.) in the licensing process. This could also be reviewed „ To ensure the safe operation of biogas plants, it by technical experts, if it is unrealistic for official makes sense to comply with the European stand- government inspections to occur. ards and guidelines mentioned in this publica- tion, such as DIN EN 60529 (Degrees of protec- „ In order to minimise or prevent problems with dif- tion provided by enclosures (IP code)). fering or uncoordinated procedures for the licens- ing and supervision of biogas plants, it is highly „ Constructively positive cooperation between plan- important for biogas plants to be treated in the ners, operators, authorities and national biogas same way across the whole country. It is therefore associations (through working groups, position advisable to develop a uniform regulatory frame- papers, sharing of experience etc.) is crucial in work that applies nationwide (law, ordinance or promoting the safe operation of biogas plants. technical code). The regulatory framework should define a state of the art for biogas plants that is in line with international requirements. It should contain all relevant requirements in one central body of rules and regulations, be easily accessible and easy to understand, and it should be updated at regular intervals. 2. Training in the industry „ Operators of biogas plants should have complet- „ Specialised companies involved in planning, ed recognised operator training and safety train- construction, operation and maintenance should ing prior to start-up. The content of this training be able to call upon defined and verifiable expert should be chosen according to plant-specific knowledge, which should also be regularly re- parameters (size, substrates etc.) and national freshed. regulations. „ Work on dangerous parts or components should „ The operators’ previously acquired expert knowl- be performed by qualified and if necessary super- edge in the field of biogas should be refreshed at vised specialised companies. regular intervals. 59 Annexes Annex 1: Hazard assessment General information about the biogas plant Operator: Tasks assigned [date]: Number of employees: Date: Persons involved in the hazard assessment: Signatures: 1. General part 1.1 General hazards - organisation Area of activity Protection measure Fulfilled Implemented Who / when Yes No Not required Responsibility Tasks, The operator is responsible for responsibilities and all tasks, responsibilities and competences are competences. Deviations are not clear or not documented. arranged properly. Outside firms are instructed by the operator. Selection of Employment of Identification of occupational employees unqualified persons aptitude before employment. (damage to health, property damage). Company eligibility criteria (e.g. education) are defined and considered. Necessary driver’s licenses are checked. New employees receive induction training. Work without To endanger Only employees with suitable appropriate oneself, other further training perform education and employees or other relevant tasks. training persons. Employees take part in relevant further training measures. Only suitable and trained persons are employed. Safety No recognition of Employees receive instruction instruction hazards or no regarding possible hazards consideration of and protection measures protection measures. before starting work. Working time Working time, Core working hours must be relaxation time and adhered to. breaks are not adhered to. Breaks must be adhered to. First aid Lack of first aid after First aid material is available. accident or sudden illness. Emergency telephone numbers are known. Trained first aider is attainable. 60 Annexes Annex 2: Instruction record for subcontractors and employees for maintenance, installation and repair work Location/place of work BIOGAS PLANT (e.g. plant) ........................................................................................ Job order ........................................................................................ (e.g. agitator repair) Responsible client/employer ........................................... Period of work Date ............................from .........................to expected finish.......................................................... Consultation on current situation required daily before commencing work Type of work / job order Electrode welding ................................................ (Shielding gas)....................................................... (Stick electrode) .................................................. Oxyacetylene welding/brazing................................. (Flame) cutting ................................................... Grinding/cut-off grinding....................................... Other:.................................................................. Executed by Outside company: Responsible site manager of outside company: .......................................................................................................................................................... Biogas plant’s own staff member: ................................................................................................ Contractor possesses the required expertise General information If employees of other employers are exposed to high levels of danger, the employers concerned must appoint a coordinator in writing to agree on the protective measures: Coordinator .................................................................... Maintenance work performed on the basis of a hazard assessment. The contractor has informed the client and other employers about hazards arising from his work for employees of the client and other employers. Personal protective equipment: selection and if applicable mandatory use (safety footwear, ear protection, fall protection, flame-retardant clothing, chemical-resistant protective clothing, protective gloves, goggles, breathing mask etc.). Observance of information signs, mandatory signs and prohibition signs. Note: In the area of the receiving equipment, toxic, very toxic, carcinogenic, mutagenic or reprotoxic deposits may be present as a result of the addition of additives and auxiliary materials (e.g. trace elements). In this case it is necessary to follow the stipulations on the safety data sheet, especially regarding personal protective equipment, and only suitable and instructed personnel must be appointed to the task. Machinery secured to prevent accidental start-up and labelled? Note: There is often no connection to the mobile phone network inside steel and reinforced concrete tanks. Transport and escape routes kept clear. Fire extinguishers, first-aid boxes and electrical distribution boxes not blocked. 61 Annexes Job induction Work procedures, possible hazards, proper use of safety precautions and environmental protection equipment discussed. Emergency plan handed out. All commissioned work always performed under supervision. Unsupervised lone working forbidden. Attention drawn to areas with a potentially explosive atmosphere. Attention drawn to possible hidden hazards (e.g. residual energy, hidden cables/pipes, elevated work equipment, pressurised pipes etc.). No bypassing or manipulation of safety equipment on machines or buildings (e.g. bridging of safetyoriented contact switches, wedging of fire doors etc.). Any (occupational safety) deficiencies detected to be reported to the operation site manager immediately. Briefing on all hazardous substances present, e.g. on the basis of safety data sheets. „ Additives and auxiliary materials (trace elements etc.). „ Flammable liquids. „ Ignitable materials (solids, dust, insulation materials). „ Risk of explosion from gases/vapours. „ Danger of asphyxiation from oxygen-displacing gases CO2. „ Toxic hazard from poisonous gases such as H2S and NH3. „ Other hazardous substances ......................................................................................... Working areas to be secured with barriers and warning notices such that no one is endangered. Compliance with operating instructions, e.g. for wheel loaders, machinery and equipment. Prohibition of alcohol and other intoxicants. Smoking bans in all marked areas. Safe use of electric tools, ladders etc. has been explained, attention drawn to need for visual inspection prior to use. Emergency measures for incidents posing an environmental risk explained. Other: Mandatory work equipment Ladders, climbing aids and occupational safety Fall protection equipment Helmet Ear protection Eye protection Special lamps (IP protection class, ATEX?) Special means of communication (IP protection class, ATEX?) Special hoists for tools and welding gas cylinders Provision of a rescue station with rescue/recovery equipment. Provision of first aid equipment. Eyewash bottle, wound disinfectant, burns first aid kit. 62 Annexes Special measures to prevent The following certificate of competence is present danger during work where (e.g. welder’s certificate for welding work on gas pipes): sparks are generated ............................................................................................................. Removal of flammable objects and materials, including dust deposits, within a radius of ...... m (also in adjacent rooms = vapour-proof? Empty conduits, cable ducts, doors, ventilation ducts?) Biogas removed from vulnerable areas? Covering over at-risk flammable objects next to and beneath the workplace. Safe sealing of openings, pipes and passages to adjacent at-risk areas and tanks connected in the gas system. Removal of potentially flammable cladding and insulation materials. Establishment of equipotential bonding (antistatic set) and humidification. CAUTION: Particular attention to be paid to small secondary fires caused by welding beads and angle grinder sparks. Elimination of risk of explosion in tanks and pipes by inerting of pipes with or N2 CO2? Protective ventilation, active ventilation significantly below LEL Fan output: .....................................................................m3/h Space to be ventilated:.....................................................m3 volume Vent tube (spiral ventilation hose) ................................... m long (distance from fresh air intake point to Ex zone/gas outlet point) Venting/extraction of gases (only use explosion-protected/ATEX blowers, e.g. to be loaned from fire brigade) Clearance measurement with a gas detector (e.g. multi-channel gas monitor) by an expert: battery charged, checked and ready for operation, etc.? Measurement of atmosphere in working area with adequate safety distance, e.g. CH4 < 0.5%; O2 > 20%, CO2 < 0.5%, H2S < 10 ppm, NH3 < 5 ppm Provision of a fire watch with extinguishing equipment. First response equipment for Fire extinguishers (note: if possible keep several different extinguishing agents ready!) fighting incipient fires water foam CO2 ABC dry powder BC dry powder water hose (connected) with spray nozzle? Permission The listed safety measures are to be implemented. The relevant regulations on industrial safety and health, hazardous materials and accident prevention (in Germany: BetrSichV, GefStoffV, TRGS 529 and DGUV) must be observed. In particular DGUV Regulation 113-001 (formerly BGR 117-1) applies to inspecting and working in tanks, digesters, pits, shafts and narrow spaces below ground level. ........................................... .......................................................................................... .......................................................................... Date: Signature of responsible employer/operator of biogas plant Signature of person carrying out the work 63 Organisations German Biogas Association The issue of safety at biogas plants has been a statu- Angerbrunnenstraße 12 tory goal of the Association since its foundation, and 85356 Freising, Germany is addressed through the following activities: Phone: +49 8161 9846-60 „ evaluation of scientific findings, practical experi- Fax: +49 8161 9846-70 ence and actual incidents E-mail: info@biogas.org „ organisation of a working group on safety and URL: www.biogas.org associated sub-groups The German Biogas Association unites operators, „ drafting of quality standards (e.g. safety rules for manufacturers and planners of biogas plants, repre- biogas plants) for the planning, construction and sentatives from science and research and all those operation of biogas plants interested in the industry. Since its establishment in „ promotion of knowledge-sharing through confer- 1992, the association, which has more than 4,800 ences and training courses members, has become the most influential organisa- „ publication of knowledge through its own spe- tion in the field of biogas worldwide. The Association cialist journal, technical texts and presentations works closely with various international organisa- tions and provides knowledge from seasoned biogas The training of biogas plant operators has become experts. This is gained from the experience gathered increasingly important in recent years. In light of with about 9,000 biogas plants in operation in Ger- this, three German associations, the German Tech- many over several decades. nical and Scientific Association for Gas and Wa- ter (DVGW – Deutscher Verein des Gas- und Was- The Association has excellent expertise and knowl- serfaches e.V.), the German Association for Water, edge in nearly all aspects of biogas, biogas plants Wastewater and Waste (DWA – Deutsche Vereini- and biogas plant operation and is involved in all of- gung für Wasserwirtschaft, Abwasser und Abfall e. ficial German and various international bodies where V.) and the German Biogas Association established standards or regulations for biogas plants are dis- the Biogas Training Network in October 2013. cussed and defined. One example is its contribution within an ISO (International Organisation for Stand- The main aim of the Biogas Training Network is to ardisation) working group to define terms, defini- provide standardised, proficient training and contin- tions and classifications of biogas systems. uing professional development for biogas plant op- erators and individuals involved in the operation of biogas plants throughout Germany. At the time of its foundation, the Biogas Training Network began with five training establishments. As of July 2016 there are 16 training organisations offering the training to obtain the operator qualification for biogas plant safety. To date, more than 3,500 people have been trained through the Biogas Training Network. Year of foundation 1992 · number of employees 43 64 Organisations Deutsche Gesellschaft The publication was jointly supported by the für Internationale Zusammenarbeit following GIZ projects: (GIZ) GmbH „ Sustainable Energy for Food – Powering Dag-Hammarskjöld-Weg 1-5 Agriculture 65726 Eschborn, Germany „ Energetic utilization of urban waste in Phone: +49 6196 79-0 Mexico (Enres) Fax: +49 6196 79-11 15 E-mail: info@giz.de „ Renewable energies and energy efficiency URL: www.giz.de in Central America (4e) „ Promoting climate-friendly biogas technology The Deutsche Gesellschaft für Internationale in Brazil (Probiogas) Zusammenarbeit (GIZ) GmbH is a global service „ South African-German Energy Programme provider in the field of international cooperation for (SAGEN) sustainable development. GIZ has over 50 years of „ Support for the Moroccan Solar Plan (DKTI 1) experience in a wide variety of areas, including eco- nomic development and employment, energy and „ Promotion of least cost renewables in Indonesia the environment, and peace and security. (LCORE-INDO) As a public-benefit federal enterprise, GIZ supports the German government – in particular the Federal Ministry for Economic Cooperation and Develop- ment (BMZ) – and public and private sector clients in around 130 countries in achieving their objec- tives in international cooperation. With this aim, GIZ works together with its partners to develop effective solutions that offer people better prospects and sus- tainably improve their living conditions. In the area of renewable energy, GIZ is currently executing more than 170 projects in over 50 coun- tries, and more than 20 of these focus on biogas or have a biogas component. These projects’ activities include the support of legal framework conditions for biogas, the analysis of different substrates for use in biogas production, capacity development, cooperation with the private sector and the support of biogas pilot projects. Year of foundation 2011 · number of employees 16,400 65 References ATEX. (2014). The European Parliament. DIRECTIVE 2014/34/EU on harmonisation of the laws of the Member States relating to equipment and protective systems intended for use in potentially explosive atmospheres (recast). BDC, D. G. (2015). Conceito de segurança para plantas de biogás. Berlin/Belo Horizonte. Comité Européen de Normalisation (CEN). (2016). DIN EN ISO 7010. Von http://www.iso7010.de/iso-7010/ abgerufen DIN EN 60529: 2014-09. (kein Datum). Degrees of Protection Provided by Enclosures. Hurst, P., & Kirby, P. (2004). Health, Safety and Environment: A Series of Trade Union Educational Manuals for Agricultural Workers. Geneve: International Labour Organisation. Rohstoffe, F. N. (2013). Leitfaden Biogas: Von der Gewinnung zur Nutzung. Fachagentur Nachwachsende Rohstoffe e.V. (FNR). SVLFG (2012). Aktuelle Entwicklungen bei der Anlagensicherheit von Biogasanlagen aus Sicht der landwirtschaftlichen Berufsgenossenschaft. Berlin. SVLFG. (2016). Technische Information 4. Kassel: Sozialversicherung für Landwirtschaft, Forsten und Gartenbau . TRBA 214. (2013). Technische Regeln für Biologische Arbeitsstoffe. Abfallbehandlungsanlagen. TRBS 1112-1. (2010). Instandhaltung. Technische Regeln für Betriebsicherheit. TRBS 2153. (2009). Technische Regeln für Betriebssicherheit (TRBS) TRBS 2153. Vermeidung von Zündgefahren infolge elektrostatischer Aufladungen. TRGS 529. (2016). Technische Regeln für Gefahrstoffe. Tätigkeiten bei der Herstellung von Biogas. TRGS 727. (2016). Technische Regeln für Gefahrstoffe. Vermeidung von Zündgefahren infolge elektrostatischer Aufladung. TRGS 900. (2016). Technische Regeln für Gefahrstoffe. Arbeitsplatzgrenzwerte. United, N. (2015). Global Harmonized System of Classification and Labelling of Chemicals. New York and Geneva. Von http://www.unece.org/fileadmin/DAM/trans/ danger/publi/ghs/ghs_rev06/English/ST-SG-AC10-30-Rev6e.pdf abgerufen 66 Publisher Fachverband Biogas e. V. Dr. Claudius da Costa Gomez (V.i.S.d.P.), Angerbrunnenstraße 12 · 85356 Freising · Germany Publisher Fachverband Biogas e. V. Phone +49 (0) 81 61 - 98 46 60 Dr. Claudius da Costa Gomez (V.i.S.d.P.), Fax +49 (0) 81 61 - 98 46 70 Angerbrunnenstraße 12 · 85356 Freising · Germany info@biogas.org, www.biogas.org Phone +49 (0) 81 61 - 98 46 60 Editor Fax Fachverband Biogas e. V. +49 (0) 81 61 - 98 46 70 info@biogas.org, www.biogas.org Authors Giannina Bontempo, Manuel Maciejczyk and Lucas Wagner Editor Fachverband Biogas e. V. Clemens Findeisen, Mareike Fischer and Frank Hofmann Authors Layout Giannina Bontempo, Manuel Maciejczyk and Lucas Wagner bigbenreklamebureau Frank Hofmann and Clemens Findeisen www.bb-rb.de Layout Cover bigbenreklamebureau Fotolia_mihalec Photos www.bb-rb.de Fachverband Biogas e.V. Photos Print Fachverband Biogas e.V., www.fotolia.de Druckmedienzentrum Gotha Print Print run 2,000 copies Druckmedienzentrum Gotha Print run 2,000 copies Status November 2016 Status November 2016 ISSN 2510-487X www.biogas-safety.org fotolia_Mihalec photo: www.biogas-safety.com 68 APPENDICES APPENDIX G – PENTAIR DOCUMENT: “CLASSIFICATION OF ATEX ZONES FOR THE PENTAIR HAFFMANN’S BIOGAS UPGRADING INSTALLATION, PROJECT BLAISE / WEST MAILLING” DATED JUNE 2019 APPENDICES APPENDIX H – 2G DOCUMENT: HAZARDOUS AREA CLASSIFICATION REPORT FOR 2G RANGE OF CHP UNITS; REPORT NO: 70066329/03; DATED 24TH APRIL 2017; CSA GROUP TESTING UK LIMITED” CSA Group Testing UK Limited Unit 6, Hawarden Industrial Park, Deeside, CH5 3US, UK. +44 (0)1244 670900 ukinfo@csagroup.com www.siracertification.com Hazardous Area Classification Report for 2G Range of CHP Units Issued on behalf of: 2G Energy Ltd Clifton House Ashville Point Clifton Lane Sutton Weaver Cheshire WA7 3FW Report No: 70066329/03 Author: J Ball Associate, CSA Group Testing U.K. Limited Technical approval: S P Lewis Compliance Specialist CSA Group Testing U.K. Limited Acceptance by 2G Energy Ltd: Date: 24th April 2017 Copyright  CSA Group Testing UK Limited. Page 1 of 23 70066329/03 1 EXECUTIVE SUMMARY No hazardous zones are required, and the overall level of risk arising from the use of natural gas or biogas and ethylene glycol solution on any of the 2G CHP units is low. Biogas and natural gas fuels are used at low pressure and the container is sufficiently well ventilated to reduce the size of the flammable gas zones to a negligible size so they may be disregarded. Glycol releases may give rise to a mist if leaks occur. However, mists are unlikely to be formed at low pumping pressures, and ignition of glycol/water mixtures is difficult, so the level of risk is low and hazardous zones are not required. In ‘standby’ (i.e. engine not running, but ready to start) the main gas valve is shut. Before the valve can be opened (and fuel gas enters the pipework within the container) the ventilation has to be running and engine has to be demanding fuel. Therefore there is no gas in the pipework and no zone within the container during ‘standby’. 2G Energy Ltd should prepare risk assessments for activities outside normal operation. Copyright  CSA Group Testing UK Limited. Page 2 of 23 70066329/03

Contains

Quotes ..............................................................................................................................4 Foreword ...........................................................................................................................5 General requirements .........................................................................................................6 1. Introduction ..............................................................................................................6 2. Terms and definitions .................................................................................................7 3. Properties of biogas ....................................................................................................9 ..................................................................................................................10 1 Executive Summary ....................................................................................................................... 2 2 Introduction .................................................................................................................................. 4 2.1 Terms of reference .............................................................................................................. 4 2.2 Summary of area classification ............................................................................................. 4 3 Hazardous materials ...................................................................................................................... 5 4 Overview of the operation .............................................................................................................. 5 5 Area classification .......................................................................................................................... 8 5.1 Exterior of the container ...................................................................................................... 8 5.1.1 Sources of release ...................................................................................................... 8 5.1.2 Ventilation ................................................................................................................. 8 5.1.3 Zoning ....................................................................................................................... 8 5.2 Interior of the container ...................................................................................................... 9 5.2.1 Sources of release ...................................................................................................... 9 5.2.2 Ventilation ................................................................................................................. 9 5.2.3 Zoning ....................................................................................................................... 9 6 Analysis ...................................................................................................................................... 11 6.1 DSEAR Regulation 5: Risk assessment ................................................................................ 11 6.2 DSEAR Regulation 6: Elimination of risk .............................................................................. 11 6.3 Potential ignition sources ................................................................................................... 12 6.4 Ignition risk assessment .................................................................................................... 13 7 Conclusion .................................................................................................................................. 14 Appendix 1 The area classification process and its relationship to DSEAR ............................................ 15 A.1.1 Grades of release ........................................................................................................... 15 A.1.2 Zone definitions ............................................................................................................. 15 A.1.3 Relationship between grades of release and zones ........................................................... 16 A.1.4 Catastrophic failures ...................................................................................................... 16 A.1.5 Area classification for indoor locations ............................................................................. 16 Appendix 2 Risk assessment nomenclature ....................................................................................... 18 Appendix 3 Calculations ................................................................................................................... 20 Appendix 4 References .................................................................................................................... 23 List of tables Table 1. Flammable gases and liquids....................................................................................................... 5 Table 2. 2G CHP units ............................................................................................................................. 7 Table 3. Zoning summary ...................................................................................................................... 10 Table 4. Summary of ignition sources (EN 1127-1) .................................................................................. 12 Table 5. Ignition risk assessment ........................................................................................................... 13 Table 6: Grades of release ..................................................................................................................... 15 Table 7: Zone definitions ....................................................................................................................... 15 Table 8: Relationship between grade of release and zone with good ventilation ........................................ 16 REPORT ISSUE HISTORY Date: Details 16/03/2016 Report /01(draft) to 2G Energy Ltd. for comments 7/04/2016 Comments by 2G Energy Ltd. on report 01(draft) received by CSA Group UK 17/03/2016 Technical check on report /01(draft) completed 7/04/2016 Report /Final issued Updated final report issued. 24/4/2017 IEC 60079-10-1:2015 applied. Indoor location considered. In this report, footnotes are indicated with a letter (a); endnotes (references to documents used) are indicated with a number (1). Copyright  CSA Group Testing UK Limited. Page 3 of 23 70066329/03 2 INTRODUCTION 2.1 Terms of reference This report has been prepared by CSA Group U.K. Limited (CSA Group) on behalf of 2G Energy Ltd. 2G manufacture a range of CHP units featuring a Biogas or natural gas fuelled engine located within a specially designed 2G container. The containerised installation is assumed to be located in a non-hazardous area, either external, or internally within a building. All sites handling significant quantities of flammable materials capable of forming a potentially explosive atmosphere come under the ATEX 1999/92/EC ‘Worker Protection’ Directive1, which is implemented in the UK by means of the Dangerous Substances and Explosive Atmospheres Regulations2 (DSEAR). The engine does not operate in a flammable atmosphere within the container and so the Product Directive (ATEX 94/9/EC) will not apply. One of the requirements of DSEAR Regulation 7 is for an area classification of the site to be undertaken, with the results marked up on suitable zoning drawings. This report covers the area classification aspect of DSEAR and includes a risk assessment for the installation. The principal code of practice used in this report is IEC 60079-10-1:20153. The area classification is given in section 5 of this report, along with the full rationale for the conclusions reached. A summary of the area classification is given in section 2.2. 2.2 Summary of area classification Biogas or natural gas is used at low pressure and the container is sufficiently well ventilated to reduce the size of the flammable gas zones to a negligible size. Glycol releases may give rise to a mist if leaks occur. However, ignition of glycol/water mixtures is difficult, so the level of risk is low and hazardous zones are not required. No hazardous zones are required inside or outside the container. Copyright  CSA Group Testing UK Limited. Page 4 of 23 70066329/03 3 HAZARDOUS MATERIALS Table 1. Flammable gases and liquids Name Mol. Lower Flash Boiling Density at Saturated App. Temp. (alternative names in mass explosive point ntp vapour pressure group class (AIT) brackets) (M) limit (air = (svp) (LEL) 1.2 kg/m3) Biogas (57% methane + 28 4.4% gas 1.2 kg/m3 gas IIA T1 (537C) 43% carbon dioxide) a Natural gas 16 4.4% gas 0.66 kg/m3 gas IIA T1 (537C) (assumed methane)b Ethylene glycol 45% 126C T2 (440C) mix with water 0.011 kPa @ 20C 62 5% (100% 105C 1065 kg/m3 IIB (100% glycol) (mono ethylene glycol)c 0.012 kPa @ 32C glycol) Natural gas and biogas may form flammable mixtures with air. Ethylene glycol is purchased as a 45% mixture with water, and is used at this dilution in the engine coolant circuits. The maximum temperature at which it is handled is 95oC. As this is below the flash point flammable vapour mixtures cannot form. However, mists or sprays of organic materials can sometimes ignite at temperatures below the flash point. Experimental work by Hull, Robertson, Mullen, Stradling and Sidwell4 has demonstrated that ethylene glycol/water mixtures are flammable, but can only be ignited under certain unlikely conditions. Their testing showed that when water/glycol mixtures containing more than 10% water are sprayed onto a hot surface any existing fire is extinguished. Water/glycol mixtures are therefore taken to be non-flammable. 4 OVERVIEW OF THE OPERATION A typical schematic diagram and layout drawing of a unit is shown on Energietechnik GmbH drawings labelled 131204_12m-CO_Avus500plus and 131204_R+I_AV500plusBG. On most 2G units the gas fuelled engine is located within a specially designed 2G container which can vary in construction depending on the noise specification required. The sizes of the containers are shown at Table 2. Control cabinets and tankage for lubricating oils are located externally to the main engine compartment. The Gbox units are typically located in a well ventilated room, and not inside a container. Containers are assumed to be located in a non-hazardous outdoor location, but may be housed inside a building, in which case the installation will be subject to a separate DSEAR assessment. Biogas or natural gas fuel is supplied to the installation at low or zero pressure. This often needs boosting to satisfy the needs of the CHP, which can be external or internal to the container. The pressure required by the 2G CHP range can vary from 20mbar for Gboxes up to 150mbar for the larger Avus units. The engine compartment is ventilated with air by a forced draft fan. Some of this air is used as combustion air in the engine, while the remainder is exhausted at the opposite end of the compartment. The engine is interlocked with the air supply. A flammable gas detector, and a smoke detector, are located at the air outlet from the container. Activation of these detectors will cause shutdown of the engine. a Hazardous properties of Biogas are conservatively taken as Methane. b Natural gas is a mixture containing (approx.) methane 88%, ethane 5.3%, higher alkanes 2.7%, nitrogen 3.0%, CO2 1.5% c BASF datasheetsfor Glysantin Protect Plus Ready Mix Copyright  CSA Group Testing UK Limited. Page 5 of 23 70066329/03 In the ‘standby’ condition, where the engine is not running, but ready to run, the main fuel gas valve is shut outside the container and therefore there is no risk of gas fuel within the container. The ventilation has to be running and the engine has to be cranking at a defined speed before the main gas valve is allowed to open. Ethylene glycol/water circuits are provided for engine cooling, heat dump and heat recovery from the engine. One of the circuits supplies heat to an external recovery system that is not considered further in this report; the other two circuits lose heat to air cooled heat exchangers located on the outside of the container. The engine exhaust vents above the container roof. The full range of 2G units is shown below at Table 2. Copyright  CSA Group Testing UK Limited. Page 6 of 23 70066329/03 Table 2. 2G CHP units Electrical power Container dimensions Ventilation rate output (standard container) Unit Biogas Natural Length Width Height Volume Biogas Natural fuel gas fuel gas kW m m3 m3/h Gbox 20 x 20 6d 2.44 2.8 41 x 350 Gbox 50 x 50 6d 2.44 2.8 41 x filius 104 50 x 6 2.44 2.8 41 7037 x filius 204 64 x 6 2.44 2.8 41 5830 x Filius R04 75 x 6 2.44 2.8 41 3661 x filius 106 100 x 6 2.44 2.8 41 5830 x filius 206 150 x 6 2.44 2.8 41 6840 x filius 404 150 x 6 2.44 2.8 41 N/A x patruus 50 50 x 6.5 3 58.5 7037 x patruus 64 64 x 6.5 3 58.5 4727 x patruus 100 100 6.5 3 58.5 5830 5897 patruus 140 x 140 6.5 3 58.5 x 6888 patruus 190 190 x 6.5 3 58.5 7603 x patruus 200 x 200 6.5 3 58.5 x 7969 patruus 240 x 240 6.5 3 58.5 x 10220 patruus 250 250 6.5 3 58.5 9472 9622 patruus 370 370 x 9 3 81 14040 x patruus 400 x 400 9 3 81 x 15719 agenitor 206 220 9 3 81 8485 8574 agenitor 306 250 9 3 81 9349 9473 agenitor 406 250 9 3 81 9272 9533 agenitor 408 360 9 3 81 13404 13600 agenitor 212 400 x 9 3 81 14316 x agenitor 312 450 9 3 81 16492 N/A avus 400c x 400 12 3 108 x 9799 avus 500a 527 12 3 108 20539 13486 avus 500plus 550 12 3 108 19057 19508 avus 500b 637 12 3 108 24737 17538 avus 500c 600 12 3 108 23365 13734 avus 800a 835 12 3 108 32417 21648 avus 800b 889 12 3 108 34507 24322 avus 800c 800 12 3 108 31397 17780 avus 1000a 1067 1063 12 3 108 41349 26482 avus 1000b 1189 12 3 108 46137 31875 avus 1000c 1200 12 3 108 47132 25720 avus 1500b 1487 12 3 108 57698 38671 avus 1500c 1560 15 3 135 60470 33738 avus 2000c 2000 15 3 135 77470 43045 avus 2000a 2200 x 15 6 3.7 333 70000 x avus 3000a 2800 x 15 6 3.7 333 90000 x d Note: not normally in a container. Copyright  CSA Group Testing UK Limited. Page 7 of 23 70066329/03 5 AREA CLASSIFICATION The principles of area classification, including terms used, are outlined in Appendix 1 For those unfamiliar with the area classification process, this Appendix should be read first. 5.1 Exterior of the container Fuel gas is drawn into the gas control train at low or zero pressure. For biogas, if the level of saturation is high, then it is cooled down to approximately 7oC to remove the condensate to an acceptable level, typically 50-60%. The biogas may also be subject to carbon filtration (or biological filtration on larger units) together with re-heating to remove H2S. Glycol/water pipework is run external to the container. The glycol-air heat exchangers are mounted on the container roof when the container is located outdoors. If the container is located indoors the heat exchangers may be relocated to a convenient location outside the building. 5.1.1 Sources of release There are no continuous or primary grade releases. Secondary grade releases comprise: -  Fuel gas leaks at flanges and screwed pipework connections and compressor seals. The bulk of the pipework is all-welded construction so there are relatively few potential leak points.  Mist releases of glycol/water mix at pipework connections. For this report it is assumed that appropriate controls are in place to prevent air ingress to any external Biogas fuel supply system so that an explosive gas/air mixture cannot occur inside the gas pipework systems. 5.1.2 Ventilation The area outside the container is normally outdoors and is naturally ventilated. If located indoors the area outside the container may be mechanically or naturally ventilated dependent on the specific site requirements. When located inside a building the site may be subject to a separate DSEAR assessment. 5.1.3 Zoning It was recognised that the calculations for zone extent from IEC 60079-10-1:2008, and used in previous issues of this report, were overly conservative for small releases of gas. HSE has carried out work to establish some more realistic figures. Clause 5.4 of HSE report RR6305 concludes that an outdoor leak of less than 1g/s of methane will give rise to a flammable gas cloud of negligible extent, even if the jet of gas is obstructed. Figure 5.7 of RR630 demonstrates that this leakage rate is not exceeded even with a hole of 5.5mm2 area. A large hole is extremely unlikely to occur. This situation has been rectified in the 2015 version of IEC 60079-10-1, and the newer version has been used for this issue of the report. Calculation 2 at Appendix 3 for outdoor and indoor releases shows that a small hole in the gas pipework will not create a flammable zone where the unit is located either outdoors or indoors, even where the room ventilation rate is as low as 0.01m3/s. So the area around the external gas pipework may be considered non-hazardous under most situations likely to be encountered. Releases of glycol/water mix may result in formation of a mist, and some such mists can sometimes ignite at temperatures below the liquid flash point. Work by HSE indicates that a flammable mist may be produced at system pressures as low as 1bar. However, experimental work by Hull, Robertson, Mullen, Stradling and Sidwell has demonstrated that when water/glycol mixtures containing more than 10% water are sprayed Copyright  CSA Group Testing UK Limited. Page 8 of 23 70066329/03 onto a hot surface any existing fire is extinguished. Therefore the ignition risk from mists can be discounted. They also found that to ignite ethylene glycol/water mixtures, the majority of the water must first be evaporated from the mixture. Then the ethylene glycol must be located where it is pocketed and heated sufficiently to establish a vapour plume with an air-fuel mixture within the upper and lower flammability limits of the vapour in essentially static air flow conditions. These conditions are not met externally to the container, and ignition of the coolant steams is improbable. 5.2 Interior of the container Enclosed within the engine compartment of the container are: -  The gas fuelled engine and its ancillary systems.  Glycol/water pipework and circulating pumps. The control compartment contains electrical control modules and lubricating oil reservoirs. 5.2.1 Sources of release There are no continuous or primary grade releases. Secondary grade releases comprise: -  Vapour leaks of fuel gas at flanges and screwed pipework connections.  Mist releases of glycol/water mix at pipework connections and pump seals. The following leak sizes may be applied in calculations (values taken from Cox Lees & Ang6) provided the joint is not subject to high thermal or mechanical stresses: -  ‘standard’ CAF-type gaskets without any spiral support: assume a leak path of 2.5 mm2  valves and ‘high integrity’ SWJ-type (spirally-wound joints) gaskets with spiral support: assume a leak path of 0.25 mm2  threaded or compression or RTJ-type (ring-type joint) joints: assume a leak path of 0.1 mm2 A hole size of 0.25 mm2 has therefore been applied in the calculations used in this report. 5.2.2 Ventilation Ventilation inside the container is independent of the location of the container. The engine compartment of the container is ventilated by a forced draft fan at a rate of shown in Table 2. The volume of the engine compartment shown in the table makes no allowance for the volume taken up by the engine or the control system compartment, so provides a conservative estimate of the ventilation provided. A congestion factor of 5 has conservatively been used in the calculation, indicating that there is significant obstruction to the air flow through the container. The control compartment is not separately ventilated. 5.2.3 Zoning As discussed at clause 5.1.3, HSE report RR630 also concludes that an indoor leak of less than 1g/s of methane will give rise to a flammable gas cloud of negligible extent providing the gas concentration at the outlet from the room is less than 10% of the Lower Explosive Limit. Calculations shown at Appendix 3 demonstrate that the gas leakage rate does not exceed 0.035g/s, the concentration of gas in the exhaust does not exceed 10% of the lower explosive limit, for any unit. A leak of pure methane has been assumed in all cases as the worst case. Biogas containing 57% methane is a more benign scenario. The normal maximum gas pressure shown at Table 2 has been used as the likelihood of 2 failures (high pressure and a leak) is considered remote. Copyright  CSA Group Testing UK Limited. Page 9 of 23 70066329/03 The worst case unit is the Gbox20 where it is enclosed in a container. Appendix 3 shows the Degree of Dilution is “High” for this, and every other unit. When the Degree of Dilution is “High” the extent of a flammable zone can be considered to be negligible, and all units are classified non-hazardous internally. These findings also apply to all units that are not inside a ventilated container, even where natural air flow to the unit may be obstructede (see Calculation 1 at Appendix 3 for outdoor and indoor releases). The overpressure within the container if a leak did ignite is shown by RR630 to be less than 10mbar. As discussed at clause 5.1.3 mist releases of ethylene glycol/water mixtures are unlikely to ignite. Also, the conditions for ignition of ethylene glycol are unlikely to be met as the temperature in the container is less than the ethylene glycol flashpoint, and there are significant ventilation air flows throughout the container. As neither fuel gas nor ethylene glycol/water can give rise to hazardous zones, the engine compartment may be considered non-hazardous. No highly flammable materials are present in the control compartment, and mist formation of lubricating oil is unlikely. The door should be kept closed when the unit is operating. The control compartment is considered to be non-hazardous. Table 3. Zoning summary Key: C = continuous grade release, P = primary, S = secondary, Amb. = ambient, Atmos. = atmospheric, Nat. = natural, Art. = artificial, Ind. = indoor, Out. = outdoor, Med. = medium, NR = no release, NE = negligible extent, NH = non-hazardous area. Drawing: Flammable materials: Biogas, natural gas, ethylene Plant: 2G Energy CHP unit See 2G energy literature glycol/water Release Temp. & press. Ventilation Hazardous area See Location of Grade Degree Source of potentially Availability no. potentially section Zone No Zone extent explosive atmosphere explosive C barg Type (m) atmosphere Fuel gas leaks from External to 1 gas pipework Non- container S Amb. 370mbarf Out Med. Good NE hazardous 4.1 Fuel gas leaks from 2 Non- Inside container S Amb. 370mbare Art High Good NE gas pipework 4.2 hazardous Glycol mist leaks from External to 3 pipework joints Non- container S Amb. 2 bar Out Med. Good NH hazardous 4.1 Glycol mist leaks from 4 Non- Inside container S Amb. 2 bar Art High Good NH pipework joints 4.2 hazardous Release from engine Control 5 compartment Non- compartment NR Amb. Atmos Nat. Med. Good NH hazardous 4.2 e Air velocity around the unit taken as 0.5m/s as suggested by IEC 60079-10-1 Table C.1 for low level obstructed outdoor conditions for lighter than air gases. f Maximum system pressure represented by cut out setting – a maximum of 150mbar is typical. Copyright  CSA Group Testing UK Limited. Page 10 of 23 70066329/03 6 ANALYSIS 6.1 DSEAR Regulation 5: Risk assessment DSEAR regulation 5 requires risk assessments that identify: - a) the hazardous properties of the substance; b) information on safety provided by the supplier, including information contained in any relevant safety data sheet; c) the circumstances of the work including: - i.) the work processes and substances used and their possible interactions; ii.) the amount of the substance involved; iii.) where the work will involve more than one dangerous substance, the risk presented by such substances in combination; and iv.) the arrangements for the safe handling, storage and transport of dangerous substances and of waste containing dangerous substances; d) activities, such as maintenance, where there is the potential for a high level of risk; e) the effect of measures which have been or will be taken pursuant to these Regulations; f) the likelihood that an explosive atmosphere will occur and its persistence; g) the likelihood that ignition sources, including electrostatic discharges, will be present and become active and effective; h) the scale of the anticipated effects of a fire or an explosion; i) any places which are or can be connected via openings to places in which explosive atmospheres may occur; and j) such additional safety information as the employer may need in order to complete the risk assessment. 6.2 DSEAR Regulation 6: Elimination of risk DSEAR Regulation 6 requires employers to 1 eliminate or reduce risk as far as is reasonably practicable 2 flammable materials should be replaced with non-flammables where possible 3 control risks and, if there remains a possible explosion risk, mitigate the effect of the explosion 4 Consider the following control measures in order of priority: a) reduce quantities to a minimum b) avoid releases c) if releases occur, control at source d) prevent the formation of an explosive atmosphere, including provision of ventilation e) collect, contain and render safe any flammable releases f) avoid ignition sources, adverse conditions; segregate incompatible substances 5 Mitigation measures to include (as appropriate): g) reduce number of employees exposed h) avoid propagation of fires/explosions i) provision of explosion pressure relief j) provision of explosion suppression k) provision of plant able to withstand explosion l) provision of PPE 6 safely handle, store and transport flammable materials 7 ensure risk-reduction measures are maintained 8 any other practical safety measures Copyright  CSA Group Testing UK Limited. Page 11 of 23 70066329/03 6.3 Potential ignition sources EN 1127-17 clause 5.2 lists thirteen type of ignition source. Table 4 summarises the ignition sources likely to be present during normal operation. Maintenance and other unusual activities have not been considered, and 2G Energy should assess the risks from these activities. Table 4. Summary of ignition sources (EN 1127-1) Ignition source Controls 1) Hot surfaces There are hot surfaces arising from the engine exhaust system inside the container and on the container roof 2) Flames and hot gases There are no flames or hot gases. The engine exhaust is released outside the container at a safe area. 3) Mechanically-generated sparks None during normal operation 4) Electrical apparatus Protection of electrical and non-electrical equipment is not known. It is assumed that unprotected equipment is installed. 5) Stray static currents, cathodic Earthing is inherent in the steel container structure. All metal corrosion protection equipment is bonded. There is no cathodic protection. 6) Static electricity Earth bonding of equipment is assumed. 7) Lightning The equipment is enclosed within a metal enclosure. Lightning is not considered to be a hazard. 8) RF electromagnetic waves from Unlikely to be present. 1011 Hz to 3 x 1012 Hz 9) Optical electromagnetic waves from Unlikely to be present. 3 x 1011 Hz to 3 x 1015 Hz 10) Ionising radiation Unlikely to be present. 11) Ultrasonics Unlikely to be present. 12) Adiabatic compression, shock Unlikely to be present. waves, gas flows 13) Exothermic reactions, including self- Exothermic or other potentially violent reactions are not carried ignition of dusts out. It is considered that hot surfaces or unprotected equipment may provide viable sources of ignition both inside and outside the container. Copyright  CSA Group Testing UK Limited. Page 12 of 23 70066329/03 6.4 Ignition risk assessment See Appendix 2 for nomenclature used in the risk assessment. Only risks to life safety have been assessed. Table 5. Ignition risk assessment event Risk of Likelihood ignition likelihood Severity ignition Overall Hazardous Controls Events release Overall +ignition leak Fuel gas leak Ignition of outside Very gas leak Hazardous zone of negligible extent. Frequent Probable Remote Low container Fuel gas leak Ignition of Forced ventilation of enclosure. inside gas leak Hazardous zone of negligible extent. Frequent Probable Remote Very Low container Engine shutdown on gas or smoke Low alarm, and on ventilation failure. Glycol leak Ignition of Forced ventilation of enclosure. Extremely inside Very flammable Very Engine shutdown on gas or smoke Frequent Remote unlikely Low container mist alarm, and on ventilation failure. Glycol leak Ignition of Extremely outside flammable Very None Frequent Remote unlikely Low container mist Leak frequency from Cox, Lees and Ang Table 11.1 for minor leak for flanges. Assuming 20 joints, likelihood = 2.10-2. Likelihood assessed as Frequent for gas and glycol joints. Ignition probability from Cox, Lees and Ang clause 15.2. Ignition likelihood = 10-2 for liquids with flashpoint <110oF. Likelihood assessed as Probable for gas leaks. Ignition likelihood = 10-3 for liquids with flashpoint >110oF. Likelihood assessed here as Remote for mist leaks given the evidence from test work by Hull, Robertson, Mullen, Stradling and Sidwell. Overall likelihood of leak resulting in ignition Frequent x Probable = Remote Frequent x Remote = Extremely Unlikely Severity of ignition of small gas leak assessed as Very Lowg – volume of gas likely to ignite is small, and explosion overpressure < 10mbar. Severity of ignition of mist release assessed as Low - volume of mist may be significant. The assessment demonstrates that the overall risk from ignition of flammable materials is low. g Figure 4.1 of HSE report RR630 indicates that the explosion overpressure is unlikely to exceed 10mbar. Copyright  CSA Group Testing UK Limited. Page 13 of 23 70066329/03 7 CONCLUSION The overall level of risk arising from the use Biogas or natural gas and glycol is low. Fuel gas is used at low pressure and the container is sufficiently well ventilated to reduce the size of the flammable gas zones to a negligible size so they may be disregarded. Gas leaks outside the container may also be disregarded under most likely conditions. Glycol releases may give rise to a mist if leaks occur, but test work has shown that ethylene glycol/water mists do not ignite. Other ignition mechanisms are considered unlikely. 2G Energy should prepare risk assessments for activities outside normal operation. This report is based on information supplied by 2G Energy, the use of relevant Codes of Practice and established calculations where appropriate. This report was checked by 2G Energy before issue and 2G Energy confirmed that, to the best of their knowledge, the data supplied is correct and no changes to the plant have occurred up to the date of the final report that might affect the assessment. CSA Group cannot take responsibility for conclusions based on data that is subsequently shown to be incorrect. The CSA Group signatories on page 1 of this report indicate by their signatures that the assumptions and predictions about releases of flammable materials to atmosphere are reasonable. Furthermore they also confirm that this report is the result of properly applying the appropriate standards and codes of practice for area classification. The (optional) signatory on behalf of 2G Energy is for use within the business, and is intended to indicate the person who takes responsibility for the report. Copyright  CSA Group Testing UK Limited. Page 14 of 23 70066329/03 Appendix 1 The area classification process and its relationship to DSEAR The following appendix is supplied for information only and is not intended in itself to impart a level of training necessary for a competent person. A.1.1 Grades of release Potential releases of flammable materials are assigned ‘grades of release’, which are defined in IEC 60079- 10-1:2008 sections 3.11, 3.12 and 3.13, as given in the table below. Table 6: Grades of release Grade of Definition release Continuous: A release which is continuous or is expected to occur frequently or for long periods (typically >1000 hours/year) Primary: A release which can be expected to occur periodically or occasionally during normal operation (typically between 10 and 1000 hours/year) Secondary: A release which is not expected to occur during normal operation and, if it does occur, is likely to do so only infrequently and for short periods (typically between 1 and 10 hours/year) The text in italics is not part of the definitions in IEC 60079-10-1 but is additional guidance found in EI15 section 1.6.4. There is no clear definition of ‘short periods’ as applied to secondary grade releases, but IEC 60079-10-1:2008 Calculation No. 7 implies that a persistence time of less than one hour once the release has stopped is consistent with the definition of a secondary grade release. A.1.2 Zone definitions The zone number assigned is based solely on the probability of an explosive atmosphere being present in a given location. Three probabilities are recognised in IEC 60079-10-1:2008 sections 3.6, 3.7 & 3.8: Table 7: Zone definitions High probability Zone 0 An area in which an explosive gas atmosphere is present continuously or for long periods or frequently. Medium probability Zone 1 An area in which an explosive gas atmosphere is likely to occur in normal operation occasionally Low probability Zone 2 An area in which an explosive gas atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only. The extent of the zone is dependent on a number of factors, e.g. the properties of the flammable materials, process pressure, leak aperture, ventilation, safety factors applied etc. Copyright  CSA Group Testing UK Limited. Page 15 of 23 70066329/03 A.1.3 Relationship between grades of release and zones In unrestricted open-air locations, the following generally apply: - Table 8: Relationship between grade of release and zone with good ventilation Corresponding Grade of release gas/vapour zone Continuous grade release zone 0 Primary grade release zone 1 Secondary grade release zone 2 However, the grade of release and zone are not synonymous. Poor ventilation may result in a more stringent zone (typical of pits, trenches and indoor situations where ventilation is limited). On the other hand, the provision of LEV usually results in a zone 2 from a primary grade release. A.1.4 Catastrophic failures It is important to note that area classification only deals with reasonably foreseeable abnormal events and does not consider highly improbable (‘catastrophic’) events. IEC 60079-10-1 section 1(d) defines ‘catastrophic’ failures as “beyond the concept of abnormality dealt with in the standard” and lists “the rupture of a process vessels or pipeline and events that are not predictable” as examples. Thus, a ‘catastrophic’ failure may cause an explosive atmosphere to be present in an area defined by area classification as ‘non-hazardous’ and such situations are subject to a risk assessment by the operator under other legislation. In area classification methodology, the concept of catastrophic failure may also be taken to include situations where two independent and unlikely events must occur for a potentially explosive atmosphere to be present. An example of this could be the failure of the LEV at the same time as failure of a flange. EI15 section 1.6.4 implies that a probability of less than 1 hour/year (the lower bound quoted for a secondary grade release) is consistent with a ‘catastrophic’ event, since a zone 2 may not be required. However, this philosophy is not universally adopted. A.1.5 Area classification for indoor locations IEC 60079-10-1:2008 introduced the concept of hypothetical volume ( Vz) for estimating the risk arising from a release of flammable gas or vapour. The later, 2015, version of the standard has revised the methodology to rectify the situation whereby overly large zones are assigned for small gas releases. In summary, IEC 60079-10-1;2015 introduces an assessment of ventilation and dilution and its influence on hazardous area (IEC 60079-10-1 Section C.3). For indoor situations the hazard depends on the ventilation rate, the nature of the expected source of gas and the properties of the gas released, particularly gas density and buoyancy. In some cases the hazard may depend on the ventilation; in others it may be almost independent of it. Ventilation is the mechanism by which air enters and leaves the room or other enclosed space. Dispersion is the mechanism by which clouds dilute. These are very different concepts and both are important. IEC 60079-10-1 Figure C.1 (based on an initial zero background concentration) provides a chart for assessing the degree of dilution, determined by the derivation of the Release Characteristic for the gas derived from: Wg / (ρg x k x LFL) (m3/s) Where Wg is the release characteristic for the gas ρg is the density of the gas or vapour (kg/m3) K is the safety factor attributed to LFL, typically between 0.5 and 1.0 Copyright  CSA Group Testing UK Limited. Page 16 of 23 70066329/03 Leak hole sizes that may be applied in calculations are provided at IEC 60079-10-1 Table B.1. For indoor situations, the background concentration must be assessed and guidance is provided in section C.3.6.2 of IEC 60079-10-1). If background concentration exceeds 25% of the LFL, the degree of dilution should generally be considered as ‘low’. Wind velocity for various locations is given at Table C.1 of IEC 60079-10-1. The type of zone for indoor and open areas is estimated from Table D.1 of IEC 60079-10-1 and the relevant grade of release, degree of dilution, and availability of ventilation. Copyright  CSA Group Testing UK Limited. Page 17 of 23 70066329/03 Appendix 2 Risk assessment nomenclature Hazard Severity Scale Life Safety Severity Minor injury. Very low (Scratch, bruise, minor cut. Injury allows normal work after First Aid Treatment) Reportable injury, lost time accident. (More severe cut, sprain, strain, minor burns. Low Restricted Duties after treatment. There may be loss of time) Permanent disability. RIDDOR serious injury. Medium (Severe burns, fractures, or back injuries. Lost time accident or .serious. injury) High Death on site, injuries off site. Potential punitive fine. Very high Death off site. Multiple deaths on site. Probable prohibition. Occurrence Likelihood Scale Frequency of Protective Examples of protective Definition outcome (years) Measures measures 10-7 Extremely Many failures need to Intrinsically safe. Full analysis of safety shutdown Unlikely occur before incident Many control measures system to establish reliability. occurs 10-5 Several control measures, Safety critical control system. Improbable A number of failures are regularly verified Guards + interlocks. needed Relief valve Instrument interlock/cut out. 10-4 1 control measure with Mechanical handling device Remote A single failure will regular verification. installed. cause an incident Validated procedure in force. Guarding Indirect control measures SOP (not validated) 10-3 Probable only, or single control PPE Foreseeable measure. Unverified control loop. Factors contrary to good practice, 10-1 e.g. uneven floors, poor Frequent No control measures Expected to happen construction standard, un-validated training. Risk Matrix Likelihood  Extremely Hazard severity Improbable Remote Probable Frequent unlikely  Very low Low Medium Low Very low Low Medium High Medium Low Medium High Low Medium High Very high Medium High Very high Copyright  CSA Group Testing UK Limited. Page 18 of 23 70066329/03 Very high / High Unacceptable - risk cannot be justified except in exceptional circumstances. Upper A.L.A.R.P. - tolerable only if risk reduction is impracticable or cost is grossly Medium disproportional to improvement gained. Lower A.L.A.R.P. - tolerable if the cost of risk reduction would exceed the improvement Medium gained. Low / Very low Broadly acceptable. A.L.A.R.P = As low as is reasonably practicable Copyright  CSA Group Testing UK Limited. Page 19 of 23 70066329/03 Appendix 3 Calculations The following extracts from an Excel spreadsheet demonstrate that the degree of dilution is “High” for all units. Biogas AREA CLASSIFICATION CALCULATIONS Calculation: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Flammable material: 20 21 22 23 24 25 26 biogas 27 biogas 28 biogas 29 biogas 30 biogas 31 biogas 32 biogas Source of release: biogas pipework leak biogas pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak Type of release pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak pipework leak Secondary pipework leak Secondary Physical form of release Secondary Gas/vapour Secondary Gas/vapour Secondary Gas/vapour Secondary Gas/vapour Secondary Gas/vapour Gas/vapour Secondary Gas/vapour Gas/vapour Gas/vapour Gas/vapour Gas/vapour Gas/vapour Gas/vapour Gas/vapour Gas/vapour Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour jet Gas/vapour Gas/vapour jet Gas/vapour jet Gas/vapour jet

Health hazards

13 of biogas: „ Inhalation of dusts or aerosols containing In light of the potential sources of danger outlined moulds, bacteria or endotoxins, for instance above it is impossible to completely rule out health from silage or dry poultry excrement that has hazards for operators, employees and third parties. become damp (SVLFG, 2016). These health hazards can be divided into four cat- egories: hazardous substances, electrical hazards, „ If activities are conducted with visibly mouldy mechanical hazards, and explosion and fire haz- wastes, it is impossible to rule out acute toxic ef- ards. fects from the inhalation of mycotoxins or other microbiological metabolic products (TRBA 214,