Safety Standards for Agricultural

Biogas Installations

Agricultural Cooperative Association

The following organizations have participated in the establishment of the new edition of
the Safety Standards for Agricultural Biogas Installations:

Fachverband Biogas e.V.

(Professional Association Biogas)
Angerbrunnerstrasse 12
85356 Freising
Germany

Fachausschuss “Chemie”
(Technical Committee “Chemistry”)
Department Explosion Protection
Resp.: Dr. Dyrba
Kurfürsten-Anlage 62
69115 Heidelberg
Germany

TÜV Süddeutschland
Niederlassung Ulm
Benzstr. 17
89079 Ulm
Germany

2
 Status 09/05/2002*

Federal Organization of Agricultural Cooperative Associations

Central Agency for Safety and Health Protection

_______________
Work Document
69
_______________

Safety Standards for Agricultural

Biogas Installations

Bundesverband der landwirtschaftlichen Berufsgenossenschaften e.V.

(Federal Organization of Agricultural Cooperative Associations)
Weißensteinstrasse 70-72
34131 Kassel
Germany

*Replaces the edition of 04/01/1998

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 TABLE OF CONTENTS

1. General.......................................................................................................................... 6
1.1 Definitions ............................................................................................................... 6
1.2 Gas Schematic of an Agricultural Biogas Installation .............................................. 7
1.3 Characteristics of Biogas ........................................................................................ 7
1.4 Dangers .................................................................................................................. 8
1.5 Note for Permits ...................................................................................................... 8
2. Facility Parts................................................................................................................. 9
2.1 General ................................................................................................................... 9
2.2 Fermentation Vessel/Fermenter/Reactor .............................................................. 10
2.3 Liquid Manure Storage.......................................................................................... 11
2.4 Gas Storage .......................................................................................................... 11
2.5 Facility Control and Process Control (PLT) ........................................................... 15
2.6 Gas Treatment ...................................................................................................... 16
2.7 Gas Pipes ............................................................................................................. 16
2.8 Armatures, Safety Systems, and Gas Carrying Facility Parts ............................... 17
3. Potentially Explosive Areas, Ex-Zone Classification .............................................. 19
3.1 Requirements/Marking .......................................................................................... 20
3.2 Classification of Zones .......................................................................................... 20
3.3 Requirements for Equipment In Explosive Areas .................................................. 25
3.4 Dimensioning of the Area of Zone 1...................................................................... 25
3.5 Dimensioning of the Area of Zone 2...................................................................... 26
4. Installation Rooms ..................................................................................................... 26
4.1 Gas Firings............................................................................................................ 26
4.2 CHP Plant ............................................................................................................. 26
5. Operation .................................................................................................................... 28
6. Fire Protection............................................................................................................ 29
Exhibit 1 Commissioning/Reoperation of a Biogas Facility .......................................... 30
Exhibit 2 Test Certificate for a Biogas Foil Storage Vessel .......................................... 31
Exhibit 3 Sample Operational Manual for a Biogas Facility in Normal Operation ...... 34
Exhibit 4 Operational Record (example)......................................................................... 36
Exhibit 5 Sample Operational Manual for a Biogas Installation during Malfunction .. 37
Exhibit 6 Shut-Off of a Biogas Installation ..................................................................... 38
Exhibit 7 Operational Instruction ..................................................................................... 39
Exhibit 8 Proposed Content of an Alarm and Hazard Protection Plan ........................ 40
Exhibit 9 Example of a Zoning Division.......................................................................... 41
Exhibit 10 Tightness of Equipment................................................................................. 42
Exhibit 11 Examples of Further Requirements and Regulations ................................. 44

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Preliminary Remarks

The Safety Standards for Agricultural Biogas Installations (Work Document 69)
comment and substantiate the requirements for installation and operation of agricultural
biogas installations, in the sense of the Instruction for Implementation of § 1 of the
Health and Safety Regulation “Work Places, Edificial Facilities, and Installations” (VSG
2.1) of Agricultural Cooperative Associations.

They shall provide advice to the planning office, the construction company in charge of
the installation, and to the operator relative to the installation and operation of
agricultural biogas installations that are operated with an operating pressure of less than
0.1 bar.

The Safety Standards represent a summary of the most important regulations, and thus
provide references to applicable regulations. In addition, the generally accepted rules of
techniques are applicable; see Exhibit 11 for examples. Deviations are acceptable if the
safety can be ensured in a different manner.

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1. General

1.1 Definitions

Biogas Installation: Installation for generation, storage, and utilization of biogas,

including all facilities and buildings necessary for operation. The
generation results from fermentation of organic matters.
Substrate: Organic matters destined for fermentation.
Fermentation Vessel Vessel in which the microbiological decomposition of the substrate
(Reactor, Fermenter, takes place.
Digestion Tank):
Gas Tank: Gas tight container or foil bag for intermediary storage of the
biogas.
Liquid Manure Container and liquid manure pit for storage of liquid manure and
Storage: the fermented substrate.
Engine Room: Room that houses the gas cleaning, gas pumping, and gas
utilization installations, including the control and feedback control
systems.
CHP Plant: Combined Heat and Power Plant - serves for the generation of
electricity and heat.
Explosive Areas: Areas in which a dangerous explosive atmosphere can develop
caused by local and operational conditions.
Zones: Explosive areas are divided into zones according to the probability
of occurrence of a dangerous explosive atmosphere.
Protection Distances: Areas around gas storage tanks for the protection of the tank and
its equipment.
Gas Treatment: Installation for cleaning and drainage of biogas.
Gas Dome: Fixture on top of the fermentation vessel in which the biogas is
collected and extracted.
Gas Storage: Room or area that houses the gas tank.

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1.2 Gas Schematic of an Agricultural Biogas Installation

Gas
Storage CHP

Fermentation
Vessel
Necessary components Optional components
AV Shut-off valve FF Gas fine filter
AL Blow-off pipe GF Gas torch
HKW CHP Plant GZ Gas counter
DS Over/under press’ protection LD Air dosing pump
O Access opening MA U-Pipe manometer
S Flame return safety RV Return valve
KA Condensate separator SG Observation window
NA Emergency switch
VS Automatic shut-off valve
UW Low pressure monitor

1.3 Characteristics of Biogas

Biogas consists essentially of methane (50 to 80 vol%), carbon dioxide (20 to 50

vol%), hydrosulphide (0.01 to 0.4 vol%), and traces of ammonia, hydrogen, nitrogen,
and carbon monoxide. In addition, suspended matters may appear.

Example: Methane 60 vol%, carbon dioxide 38 vol%, residual gases 2 vol%

Biogas Natural Propane Methane Hydrogen
Gas
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 700 650 470 650 585
Max flame propagation m/s 0.25 0.39 0.42 0.47 0.43
speed in air
Explosion area Vol% 6 - 12 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

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1.4 Dangers

The following dangers and risks can arise when using biogas:
• Danger for life and health by suffocation or poisoning in ducts or containers,
e.g., H2S, CH4, CO2
• Health hazards by co-fermentation matters
• Explosion of ignitable gas/air mixtures
• Development of fires
• Freezing of gas or substrate pipes, causing consequently an unintended
blockage of pipes
• Development of condensates, particularly through cooling of water saturated
gases, with the danger of freezing and blocking of pipes
• Plugging of pipes, particularly of gas and substrate pipes

1.5 Note for Permits

For the construction of a biogas installation, the applicable regulations have to be

complied with, e.g., relative to construction, water, health and occupation, hazard,
and immission protection laws.
Depending on the type and size of the foreseen measures, approval processes have
to be pursued in these legal areas. However, even for those measures that are not
subject to an approval, the material regulations in the different areas and the
technical requirements have to be met.
Generally, an approval process will have to be executed in accordance with the
construction law or the BImSchG (Immission Protection Law), taking also under
consideration the requirements of the water laws.
There is a registration requirement with the responsible customs office for the
generation of biogas and the use of heating oil as ignition oil for the Biogas-CHP
Plant.

1.5.1 Approval Process

1.5.1.1 New Construction of a Biogas Installation
An application for construction approval has to be filed for all construction
facilities, e.g.:
- Fermentation vessel
- Room for the installation of the gas storage tank
- Tank for gas storage
- Room for installation of the heat generator/CHP Plant, etc.
The construction regulations of the particular state have to be respected.

1.5.1.2 Installation of a Biogas Facility into Existing Structures

8
 The installation of parts of a biogas facility into existing structures requires a
construction approval if farther reaching regulations are applicable for the new
use of the structure than were applicable for the previous use. This is the case if,
for example, gas storage tanks or heat generators/CHPs are to be installed in
existing rooms. For such case, the construction approval application and the
construction documents can be limited to the rooms with changes use.

1.5.2 Occupational Health Regulations

1.5.2.1 Regulation for Electrical Installations in Hazard Areas (ElexV)
The ElexV will be rescinded on 01/01/2003 and will be replaced by the
Operational Safety Regulation (BetrSichV).
The regulation is applicable for installation and operation of electrical facilities in
explosion hazard areas. Explosive atmosphere can particularly develop:
- in rooms in which gas is stored or generated, or which are connected through a
ventilation system,
- in channels or collecting basins,
- inside of equipment, containers, and pipes that contain biogas,
- around facility parts with operational release of combustible matters, such as
overpressure valves at fermentation vessels or gas storage tanks.
Rooms for installation of gas consumption facilities (fireplaces, engines), which
are not in connection with rooms for gas storage or gas generation, do not fall
under the area of application of the ElexV. In such rooms, the installation of parts
transporting or carrying gas or electricity shall be clearly laid out and, as far as
possible, be installed at different walls.
The ElexV specifies the required tests before initial operation and repetitive tests.

2. Facility Parts

2.1 General
Biogas facility parts are facilities, structures, buildings, and rooms that are necessary
for operation and safety of the biogas facility.
2.1.1 Those parts of the biogas facility that are installed above ground outside have to
have safe foundations. They have to be installed in a way that they are well
accessible. Sufficient stability has to be ensured.
2.1.2 In order to avoid the appearance of differences of electrical potential, all facility parts
that are electrically conductive have to be connected with each other, as well as with
the protective conductor and the ground conductor (potential equalization).
2.1.3 Gas transporting parts of the biogas facility have to be protected against chemical
influences, as well as against mechanical damage in risk areas (e.g., protection
against collision in driving areas).

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2.1.4 Maintenance and operation stands, as well as operational panels, for stirring
machines, pumping devices, and rinsing devices should be installed above ground. If
that is not possible, a fixed forced ventilation system has to be existent. Before
accessing the area, sufficient air exchange has to be ensured (user manual and
markings have to be observed).

2.2 Fermentation Vessel/Fermenter/Reactor

2.2.1 Heat Insulation
The heat insulation of fermentation vessels must comply as a minimum with norm B 2
DIN 4102 for normal inflammability. For an area of one meter around openings, out of
which gas leaves operationally, it must consist of material that is difficult to inflame,
according to B 1 DIN 4102.
2.2.2 Access Openings
Access openings must have a diameter of at least 800 mm, or have a size of at least
600 x 800 mm. If entering into the container is necessary for maintenance and repair
work, sufficient ventilation has to be possible; the same security measures are
necessary for the entrance into revision shafts.
2.2.3 Electrical Installations
Electrical installations inside of continuously operated fermentation vessels have to
comply at least with the requirements of Zone 2.
Submersible motor stirring machines and submersible motor pumps have to be
protected at least with protection type IP 68 and shall only be operated in submerged
state. This has to be ensured by a User’s Manual.
Equipment inside of discontinuously operated fermentation containers (e.g., batching
process) has to comply with the requirements for Zone 1.
2.2.4 Safety Devices
Fermentation vessels have to be equipped with safety installations that are effective
at any time and that prevent an impermissible change of the internal pressure.
Closures for liquid have to be designed as safety closures in a way that the sealing
liquid does not leak and flows back by itself at decreasing over or under pressure.
It has to be ensured for the fermentation vessel and the post fermentation vessel that
the fill level is not exceeded, e.g., by feeding the fermented substrate via a frost-
protected rising pipe (overflow) to the liquid manure storage.
2.2.5 Fill Openings
Fill openings have to be secured against falling into them. Measures against falling
are, e.g.:
- Covered filling funnel with a height of > 1.30 meter in combination with a cover
- Filling funnel with a height of > 1.80 meter
- Fixed installed grate with bar distances of ≤ 20 cm

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 - Self-closing flaps for vertical openings
- Fill channels with covered vertical openings
If the above measures cannot be used because of the consistence of the
decomposition material, other protective measures with the same safety for
personnel against falling into the facility have to be used.
2.2.6 Safety Installations against Gas Hazards at Fill Openings
Fill openings should be located relative to the main wind direction in a way that gases
are led away from the operating area.
For locations inside buildings, fermentation gases have to be forced to exit. The
installation for conducting gases off has to be automatically switched on during filling.
If necessary, an operation stand has to be foreseen for filling funnels for safe control
of the rinsing hose.
The gas dangers in the close proximity of the filling device have to be pointed out.
2.2.7 Discontinuous Fermentation (e.g., batch)
No gas dangers shall develop during charging or removal of containers for
discontinuous fermentation.

2.3 Liquid Manure Storage

The regulations for prevention of accidents by the Agricultural Cooperative
Associations apply for the construction, installation, and operation.

2.4 Gas Storage

2.4.1 Gas Tank (pressure < 0.1 bar)
Gas tanks are to be installed, maintained, and operated in a way that the safety of
the facility operator, operating personnel, and third parties is ensured.
Gas tanks have to be gas tight, pressure-resistant, as well as media, UV,
temperature, and weather resistant, in accordance with the requirements.
The following requirements have to be fulfilled relative to the selection of materials,
particularly for foils made of plastic:
- Tear strength: min. 500N/5cm, or
- Tensile strength: min. 250N/5cm
- Gas permeability relative to Methane: ≤ 1000 cm3/cm2 • d • bar
- Temperature resistance from -30°C to +50°C
Gas tanks have to be tested for tightness before initial operation.
2.4.2 Safety Devices
Safety devices effective at all times shall prevent an inadmissible change of the
interior pressure.
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2.4.3 Aeration and De-Aeration of Gas Storage Rooms
Rooms for installation of gas tanks have to have effective ventilation (transverse
ventilation). Diagonal ventilation should be attained. The opening for air supply shall
be located near the floor, the opening for extracted air below the ceiling.
The openings for supply air and extracted air shall have the following minimum cross
sections:

Gas Tank Cross Section

Volume

≤ 100 m3 700 cm2

≤ 200 m3 1000 cm2

> 200 m3 2000 cm2

2.4.4 Doors
Doors have to open toward the outside and be lockable.
2.4.5 Safety Distances (a)
In order to reduce the interaction in an event of damage, or in case of fire to prevent
encroaching on close-by installations, as well as for the protection of a gas tank from
an event of damage such as heating caused by fire, safety distances (fire breaks)
according to Tables 2.4.5.2 to 2.4.5.4 have to be foreseen between the gas tanks
and neighboring facilities, installations, buildings, or traffic ways not belonging to the
biogas facility. Inside the biogas facility, safety distances of at least 6 meters are to
be foreseen between gas tank and rooms for installation of combustion engines or
electrical switching installations (see Section 2.4.5.5).
Remark
If several gas tanks of a facility have to be recognized as a unit because of their
arrangement, the safety distances (a) result from the addition of the individual gas
volumes.
2.4.5.1 Dimensioning of the Safety Distances
For above ground installations, the safety distance is measured from the vertical
projection of the rim of the storage container. For safety distance (a) see Sections
2.4.5.2 to 2.4.5.5.
2.4.5.2 Above Ground Fixed Gas Storage
These include also foil storage in fixed containers or installation rooms, e.g., in former
fermentation food silos or containers.

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 Gas volume in To 300 More than More than More than Material selection for outer
m3 per tank 300 to 1,500 to 5,000 walls
1,500 5,000
Safety 3 3 6 10 Not flammable,
Distance (a) in construction material class
meters A, fire-retardant (F30),
smoke protected
Safety 3 6 10 15 Not flammable,
Distance (a) in construction material class
meters A, smoke protected
Safety 6 10 15 20 Other, from flammable
Distance (a) in materials of construction
meters material class B

2.4.5.3 Underground and Earth Covered Gas Storage

Safety distances around armatures and openings
Gas volume in m3 To 300 More than 300 to More than 1,500 to More than 5,000
per tank 1,500 5,000
Safety Distance 3 6 10 15
(a) in meters
Note
If earth covered tanks cannot be driven on without limitations, they have to be
marked and equipped with a barrier.

2.4.5.4 Balloon and Pillow Storage as well as Foil Storage above Liquid Manure Storage or
Fermentation Vessels
Safety Distances

Gas volume in m3 To 300 More than 300 to More than 1,500 to More than 5,000
per tank 1,500 5,000
Safety Distance 4.5 10 15 20
(a) in meters

2.4.5.5 Protection Wall

The safety distance can be reduced by sufficient earth coverage, by a sufficiently
dimensioned protection wall, or by a fire barrier insulation (e.g., fire protection wall of
fire resistance class F 90 according to DIN 4102). Doors in protection walls have to
be fire resistant and self-closing (T 90 according to DIN 4102). When using a
protection wall of fire resistance class F 90 A with a protection coverage of 3 meters
toward the sides and above, the safety distance can be reduced to zero.
A protection wall may also consist of a building wall with similar characteristics and
without openings.

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Picture: Protection Wall Arrangement

Example 1: No Protection Wall

Biogas Storage

Building

Example 2: a = a1 + a2 Protection Wall between Storage and Building

Biogas Storage

Protection Wall

Building

Example 3: Protection Wall Part of the Building

Biogas Storage
Protection Wall

Building

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2.4.5.6 Requirements within the Safety Distances
Within the safety distances:
- No combustible materials in quantities above 200 kg may be stored without
additional protection measures, and there may be no other buildings, public
streets, or roads located. Additional protection measures may include, for
example, fire prevention, fire protection, or fire fighting measures (see, e.g.,
Section 2.4.5.5).
- Traffic routes are permissible if necessary for the operation of the facility.
- Machines and activities that could lead to an endangerment for the gas tank (e.g.,
welding, cutting) are forbidden without additional protection measures.
- Fire, open light, and smoking are forbidden.
2.4.5.7 Marking
Areas in which safety distances have to be respected, including, as case may be,
also access to gas tanks, must be marked according to VSG 1.5.
Examples for Marking

P02 Fire, open light, P06 Access forbidden

and smoking forbidden for unauthorized persons

2.4.6 Mechanical Danger

2.4.6.1 Gas storage and its equipment have to be protected from mechanical damage.
Gas tanks and their equipment in dangerous areas have to be protected from
being hit by vehicles by, for example, barricades, fences, or implementation of
safety distances.
2.4.6.2 Openly accessible pillow storage or foil covers made of flexible materials have to
be protected against mechanical damage. This requirement will be fulfilled, for
example, by a protection fence erected around the pillow storage. If the distance
of the protection fence is less than 850 mm, the fence has to be protected against
reaching through. The protection fence has to be established as a climb-through
protected fence using wire netting with a height of at least 1.50 meters.

2.5 Facility Control and Process Control (PLT)

PLT installations have to be divided into operation control protection and damage
limitation devices (see, e.g., VDI/VDE-Guideline 2180, DIN V 19 250).

15
 Central Emergency Shut-off System and Shut-Off Criteria
Both quick acting gate valves in the gas safety line have to be controlled in a way
that the gas supply to the engines is not released until start of operation and
interrupted during operation under the following conditions:
- Exceeding of rpm
- Falling below the minimum gas pressure
- Exceeding the maximum gas pressure
- Activation of the temperature limiter in the cooling circuit
- Use of the emergency stop switch
- Failure of control power
- Activation of the gas alert and fire detection systems, or the temperature
monitoring system of the air in the room
- Failure of the ventilation system
Control devices with safety function have to be designed to be safe themselves,
unless they are secured by means of a redundant system, e.g., a mechanical over
pressure safety device or a free level overflow pipe against overfill.

2.6 Gas Treatment

2.6.1 Desulphurization by Ferrous Materials or Active Coal

If biogas is desulphurated using ferrous materials or active coal, there is a danger of
self-heating during regeneration. The safety notes of the manufacturers have to be
complied with in order to avoid this.
2.6.2 Desulphurization by Adding Air into the Gas Volumes of Fermentation Vessels
The air-dosing pump has to be set so that it transports at most a volume flow of 12%
relative the biogas generated in the same time frame. The air dosage has to be
dimensioned in a way that even with a failure of flow control, no substantially larger
air volumes can be moved. The inlet pipe for the gas room requires a non-return
valve.

2.7 Gas Pipes

2.7.1 Gas transporting pipes have to be designed in accordance with generally accepted
engineering rules. The professional manufacturing and tightness has to be proven,
e.g., by certificate by the manufacturer (see sample in Exhibit 2).
Pipes have to be resistant against media and corrosion. Pipes resistant for biogas
are, for example, pipes made of steel, stainless steel, polyethylene (PE-HD), and
PVC-U.
16
 Note
Copper is not resistant against biogas; according to experience, brass and red brass
are suitable (commercial PVC-KG pipes are not admissible, since their design
strength corresponds to a maximum of 0.5 bar).
Pipes, including fixtures and flexible connections, have to have design strength of at
least one bar.
2.7.2 Generally, steel pipes have to be used. Plastic pipes may be used outside of closed
rooms, such as buildings, parts of buildings, or containers, for installations below
ground level generally, and above ground level, as a connection line for the foil
storage and as connection line of the fermenter. Plastic pipes have to be protected
from mechanical and thermal damage. Coupling sleeve connections, which are not
designed as longitudinal frictional connections, have to be secured against shear in
accordance with occurring pressures. The pipe connections have to be frictional
connections.
2.7.3 Mechanical damage by settlement (e.g., for passage through a wall) has to be
prevented by using appropriate fixtures and corresponding connections.
2.7.4 In case of moist gases, attention has to be paid relative to a freezing safe installation
of the pipes. Condensate off-takes have to be designed for the installation to be
freezing safe and always functioning.
2.7.5 Connection pipes to the gas tank within the installation room of the gas tank are
considered part of the gas tank.
2.7.6 Pipes have to be marked in accordance with DIN 2403 corresponding to the flowing
substance and the flow direction. Marking color: yellow.
The location of underground gas lines has to be marked by a gas line warning stripe.
2.7.7 The suitability of gas carrying flexible connection pieces belonging to the CHP Plant
have to be certified by the manufacturer of the CHP Plant.

2.8 Armatures, Safety Systems, and Gas Carrying Facility Parts

2.8.1 Armatures, safety systems, and gas carrying facility parts have to be installed
freezing safe in accordance with the generally accepted engineering rules and have
to be tested for tightness. Relative to tightness, they have to comply with the
requirements of BGR 104 Section E 1.3.2 “Tightness of Equipment” (see Exhibit 10).
In addition, they have to be media, corrosion, and pressure resistant.
2.8.2 Armatures and gas carrying facility parts, which do not have a DVGW certification,
have to be designed for a pressure resistance corresponding to ten times the
operational pressure and have to be biogas resistant, e.g., inspection glass, cover for
an access opening.

17
2.8.3 It shall be possible to operate armatures from a safe stand. Armatures for gas
extraction have to be secured against unauthorized or inadvertent opening, e.g., by
securing the handle.
2.8.4 Condensate separator and safety systems have to be accessible at all times.
Pressure control units with sealing liquid in over or under pressure safety devices, as
well as condensate and dirt separators, must be controllable and maintainable easily
and safely, without having to enter into pits or shafts.
Pressure control units with sealing liquid have to be designed in a way that in case of
actuation the sealing liquid cannot exit but rather flows back automatically. In order to
avoid emission of gas, the pressure of water seals that function as a condensate
separator rather than as an over/under pressure safety device has to be at least five
times the actuation pressure of the over pressure safety device.
2.8.5 In front of gas consumption devices, such as heating boilers and CHP facilities, flame
traps have to be installed as closely as possible to the consumer in accordance with
the instructions by the manufacturer. Only certified armatures have to be used.
Gravel pits have to be type certified.
Recommendation
Existing facilities with gravel pits without type certification should be refurbished with
type certified gravel pits or type certified flame filters when major changes of the gas
system or an exchange of an aggregate are implemented. It is recommended that the
refurbishment be executed within five (5) years of the publication of these safety
regulations.
The arrangement of components has to be done in accordance with Schematic 1.2.
2.8.6 Arrangement of Over and Under Pressure Safety Devices
2.8.6.1 Each gas tight vessel in which biogas is being produced has to be equipped with
at least one safety device against exceeding or under-running of the pressure.
The gas escaping in case of actuation has to be led off safely. The reliability and
suitability of the safety device has to be proven by component marking and
individual test. It has to be ensured by means of a separate under pressure
sensor or a similar device in the gas system that a forced shutdown of the gas
consumption equipment and a malfunction message are initiated before actuation
of the under pressure safety device.
The over and under pressure safety devices within the facility have to be
designed, arranged, and monitored, and the biogas facility as a whole has to be
operated in a way that all operational states of the fermenters can be safely
controlled. The formation of foam represents a malfunction and has to be
prevented by means of operational measures within the facility. Damage by the
formation of foam has to be prevented, e.g., by a burst safety device, a pressure
relief safety device, or sufficient storage volume. The suitability of the over/under
pressure safety device has to be proven by means of a comprehensible
calculation and a functional description. If designed for submersion, it has to be
ensured that it does not run empty or dry and does not freeze.

18
 The operational manual has to point out that the function of safety devices has to
be verified always after facility malfunctions, and once a week during normal
operation.

Note
Safety devices may become ineffective, for example, by sluggishness caused by
dirt or corrosion, by plugging, or by freezing.
A change of the interior pressure can be caused by:
- gas production without discharging,
- addition or discharging of gas or substrate by means of pumps.
Liquid seals as a safety device have to be designed so that the sealing liquid
flows back automatically with over or under pressure.
The feeding pipes for over or under pressure safety devices must not have the
possibility for manual shut-off.
Over and under pressure safety devices have to safe against freezing.
2.8.6.2 Relief pipes for over or under pressure safety devices have to:
- open at least 3 meters from the ground, and
- open one meter above the roof or the rim of the vessel, or
- be away from buildings and traffic ways by at least 5 meters.
Alternately, free flow off has to be proven. The one-meter area around the
opening of the relief pipes is Zone 1.
The blow off of biogas in case of malfunctions of the gas consumption facilities is
not admissible without limitations. If the gas volumes to be expected in such
cases exceed a volume flow of 20 m3/h, the blow off volumes have to be limited to
such value by appropriate measures, or gas burn off has to be used.
Appropriate measures are, e.g.:
- Existence of a second gas consumption facility, independent from each other,
and corresponding reduction of the substrate supply. Not later than 48 hours
after the malfunction event, the remaining gas consumption has to be in a
position to reduce the residual blow off gas volume to 20 m3/h.
- Proof of a suitable location for positioning the connection possibility and the
availability of a mobile burn off facility within 24 hours.
The exhaust gases of the gas burn off have to be conducted away over the roof
or through an exhaust pipe, which has to be away from buildings or traffic routes
by at least 5 meters, and the opening has to be located at least 3 meters above
ground.

3. Potentially Explosive Areas, Ex-Zone Classification

19
3.1 Requirements/Marking
Since one has to consider the existence of explosive gas/air mixtures in the vicinity of
gas tanks and fermentation vessels, zones have to be implemented in accordance
with Section 3.2. Measures for the avoidance of ignition sources have to be taken in
accordance with BGR 104 Section E 2, “Measures that Prevent the Ignition of a
Dangerous Explosive Atmosphere” in explosive areas, e.g., prevention of sparking,
interdiction of fire and smoking.
Explosive areas have to be marked by using appropriate signage with black letters on
yellow background, e.g.:

3.2 Classification of Zones

Explosive areas are three-dimensional spaces in which, because of local or
operational conditions, a dangerous explosive atmosphere may develop.
Explosive areas are divided into zones according to the probability of the
development of a dangerous explosive atmosphere (see Exhibit 9).
The following is valid for areas that are explosive because of gases:

Zone 0 contains areas in which the dangerous explosive atmosphere, which consists of a
mixture of air and gases, vapors or mists, is present continuously, long-term, or
often.
Remarks
The term “often” has to be understood as “most of the time”.
Explanations
During normal operation of biogas facilities, Zone 0 is practically non-existent. In
addition, the fermentation vessel does not contain explosive mixtures. At most, the
intake manifold of the combustion engine or the combustion chamber for the gas
burn off contains, in accordance with their purpose, an explosive mixture. This area is
sealed off from the remaining gas system by flame traps.

Zone 1 contains areas in which it has to be taken into account that a dangerous explosive
atmosphere consisting of gases, vapors, or mists develops occasionally.
Explanations
20
 Occasionally, an explosive mixture develops in biogas facilities around the openings
of blow off pipes of gas over pressure safety devices and of gas burn off installations
(see Section 3.4).

Zone 2 contains areas for which the development of a dangerous explosive atmosphere
consisting of gases, vapors, or mists does not have to be considered, but if it
develops anyway, then only with a low probability and short term.
Explanations
The rare appearance of explosive gas mixtures can generally develop during a
malfunction or during service activities.
In the area of the fermentation vessel, this is valid for the maintenance and cleaning
openings and the interior of a continuously operated fermenter. For gas storage, this
concerns the gas tank and the vicinity of the ventilation inlets and outlets (see
schematic drawing).

21
Examples for Ex-Zones

Observation glass,
technically tight
Stirring machine,
service opening

Prep pit
Fermentation
Vessel Over pressure
Safety device

Spatial extent of Ex-Zones

spherical upwards

Protection wall,
smoke protected
F 90

Ventilation gas tank Gas Tank

Door T 30 self closing

Ventilation gas tank

22
Outside Foil Gas Storage

Top View

Biogas storage

Protection wall

Building

Side Elevation View

Protection wall

Building

Biogas storage

23
 Example Ex-Zones
Fermentation vessel with foil cap

Fill level max

Fill level min

Enclosed foil gas storage

Side elevation view

Protection wall
Opening
ventilation

Building

Biogas storage

Protection wall

Opening
ventilation
Building

Biogas
storage

24
Top View

Biogas storage

Ventilation intake

Ventilation
outlet

Building

Protection walls

3.3 Requirements for Equipment In Explosive Areas

For the selection of electrical components, see VDE 0165 Part 1.
3.3.1 Requirements in Zone 0
Only such equipment may be used in Zone 0 that is certified for Zone 0 and that is
marked accordingly.
Note
Confirmations of conformity for Zone 1 are not sufficient.
As of 06/30/2003, only such equipment and protection systems may be used that are
classified Group II Category 1 according to Exhibit 1 of Regulation 94/9/EU.
3.3.2 Requirements in Zone 1
Only such equipment may be used in Zone 1 that is certified for Zone 0 or 1 and that
is marked accordingly.
As of 06/30/2003, only such equipment and protection systems may be used that are
classified Group II Category 1 or 2 according to Exhibit 1 of Regulation 94/9/EU.
3.3.3 Requirements in Zone 2
Only such equipment may be used in Zone 2 that is certified for Zone 0, 1, or 2 and
that is marked accordingly.
As of 06/30/2003, only such equipment and protection systems may be used that are
classified Group II Category 1, 2, or 3 according to Exhibit 1 of Regulation 94/9/EU
(see, e.g., prEN 13463, EN 13 478).

3.4 Dimensioning of the Area of Zone 1

The area of Zone 1 is defined as the circumference of one meter around facility parts,
equipment parts, connections, view glasses, transfer openings, service openings of
the gas tank, and of that part of the fermentation vessel that is exposed to gas, as far

25
 as an operational exit of biogas has to be accounted for, as well as around the
opening of blow off pipes (see BGR 104 Section E 1.3.2.3, Exhibits 9 and 10).
The distance of one meter is valid for free ventilation. A distance of 4.5 meters has to
be respected in enclosed rooms.

3.5 Dimensioning of the Area of Zone 2

Facility parts exposed to gas:
The area of Zone 2 is defined as the circumference of 3 meters around those facility
parts, equipment parts, connections, transfer openings, service openings, and
bursting discs, which are classified as technically tight. The distance of 3 meters is
valid for free ventilation. Enclosed rooms are entirely considered as Zone 2 (see BGR
104 Section E 1.3.2.2, Exhibits 9 and 10).
The area of Zone 2 is defined as the annulus of one meter to 3 meter around facility
parts, equipment parts, connections, view glasses, transfer openings, service
openings of the gas tank, and of that part of the fermentation vessel that is exposed
to gas, as far as an operational exit of biogas has to be accounted for, as well as
around the opening of blow off pipes.
Gas storage:
For a foil storage vessel, installed outside or in a room with ventilation all around, the
area of Zone 2 comprises the circumference of 3 meters, upwards and sideways, and
downwards for 2 meters with an inclination of 45°. If the foil storage vessel is placed
in a smoke proof and therefore essentially air tight room, Zone 2 is comprised of the
interior of the gas storage room, as well as the circumference of 3 meters upwards
and sideways around the ventilation intakes and outlets; the extension downwards is
2 meters with an inclination of 45°.
Rooms can be made smoke proof by, e.g.:
- Open face brick or plastered walls
- Concrete walls
- Walls with cladding made of noncombustible and grouted plates
- Norm container with metal walls
Note
There is no zone around permanently technically tight facility parts according to BGR
104 Section E 1.3.2.2 (see Exhibits 9 and 10).

4. Installation Rooms
4.1 Gas Firings
The Technical Regulations for Gas Installations (DVGW-TRGI 1986, edition 1996) is
applicable for installation rooms for gas installations.

4.2 CHP Plant

4.2.1 Installation in Outbuildings without Lounge

26
4.2.1.1 Installation rooms have to be dimensioned so that the CHP Plants can be
installed, operated, and maintained orderly. That is normally the case if the CHP
is accessible from three sides. Doors have to open in direction of escape.
4.2.1.2 Floor drains must have oil separators. Alternately, an oil collection tank has to be
installed below the engine that is able to receive the total oil volume of the engine.
4.2.1.3 Installation rooms must have intake and outlet openings for ventilation that cannot
be closed and that allow lateral ventilation. When using technical ventilation, it has
to be ensured that the outgoing air is drawn from the vicinity of the ceiling. In such
case, it is irrelevant whether the air intake is located low or high in the room.
When using natural ventilation, the air intake has to be located in the vicinity of
the floor, the opening for air exit at the opposing wall near the ceiling.
Note
The free minimum cross section ”A” of the opening for air intake or outlet results
from the following equation:

A = 10 P + 175 A = free cross section, in cm2

P = maximum electrical power delivered by the
generator, in kW
Example: 22 kWel = 395 cm2
30 kWel = 475 cm2

4.2.1.4 It must be possible to shut the CHP off at any time by means of an illuminated
switch located at the outside of the installation room. The switch has to be marked
well visibly and permanently by “Emergency Switch CHP”.
4.2.1.5 It shall be possible to shut the gas supply for the CHP off from outside the
installation room as closely as possible to the CHP room. The open and closed
positions must be marked.
4.2.1.6 In case of engines that use a turbo charger for compressing the gas-air mixture,
the following precautions have to be taken to prevent explosive mixtures in case
of emergencies:
a) monitoring of the air in the installation room using type certified equipment and
automatic shut-off of the aggregate and the electrical installations, or
b) monitoring of the air in the installation room using type certified equipment and
automatic shut-off of the aggregate and simultaneous switch-on of a forced
ventilation installation, which is dimensioned according to c) so that no
explosive mixtures can develop, or
c) forced ventilation of the aggregate room with at least an air exchange that
effects sufficient dilution for the maximum possible gas volumes. The
necessary minimum air exchange is 35 m3/h of air for each one kilowatt
electrical power installed. This results in a maximum gas concentration of
maximum 1.5 vol%, which corresponds to about 25% of the lower gas
explosion limit (biogas 6 to 12 vol%).

27
 With open shut-off valves, the ventilator must operate, and its function has to
be monitored by a flow guard.
4.2.1.7 Two shut-off valves have to be installed before each engine aggregate, which
shut off automatically with standstill of the engine. The leak tightness of this pipe
portion has to be verified on a regular basis. If the supply line to the engine is
operated continuously with an over pressure of > 5 mbar even with engine
standstill, an automatic supply line monitoring is necessary.
Recommendation
Existing installations have to be refurbished in case of essential modifications of
the gas system or the exchange of an aggregate. It is recommended to execute
the refurbishment within five (5) years after publishing of these safety guidelines.
4.2.1.8 Rooms into which gas can intrude and that have to be accessible on a regular
basis for the operation of the facility have to be ventilated in a way that no
dangerous gas mixture can develop. Exit from such rooms shall be possible
without entering into the CHP room. If these rooms cannot be ventilated
accordingly, an explosion protection has to be foreseen. In addition, the MAK
values have to be complied with safely and permanently.
Explanation
Such rooms are considered Zone 2 (see Section 3).
4.2.2 Installation in Residential Buildings
4.2.2.1 The regulations of Sections 4.2.1.1 to 4.2.1.8 are applicable.
4.2.2.2 Walls and columns, as well as ceilings above and below installation rooms, have
at least to be fire protected according to F 90 A DIN 4102 and consist of
noncombustible materials. Claddings and insulation layers made from
combustible materials may not be used for walls, ceilings, or columns.
4.2.2.3 Doors in fire resistant walls have to be at least fire retardant, according to T 30
DIN 4102, and have to be self-closing; this is not applicable for doors that lead to
the outside.
4.2.2.4 Ventilation ducts and other pipes may only be installed across walls and ceilings if
the pipes themselves cannot transfer fire or if preventive measures against
transfer of fire have been taken (e.g., insulation of cables with general
construction certification, fire protection flaps).
Open areas in the opening have to be filled with noncombustible materials that
are resistant to deformation.

5. Operation

An operational manual has to be available for initial operation (see sample in Exhibit
1). The initial operation of the installation has to be done by the specialized
professional (see the Acceptance Protocol in Exhibit 2).
Operation and maintenance of biogas facilities may only be assigned to reliable
persons who are familiar with the tasks. Attention has to be paid to the operational
manuals with the safety instructions (see Exhibit 3).

28
 The operational instructions have to be placed permanently in the operation room
(see, e.g., Exhibit 7).
It is recommended to maintain an operational record (see Exhibit 4) that contains all
daily measurements, control and maintenance activities, as well as malfunctions.
In case of a malfunction of the gas consumption equipment, the gas production of the
facility has to be reduced by means of appropriate measures in order to keep the
blow off volumes as small as possible.
Appropriate measures for the reduction of the gas production are, e.g.:
- Interruption of the supply of substrate
- Shut-off of heat supply to the fermenter
In case of malfunctions and for a shut down of the biogas facility, the measures
according to Exhibits 5 and 6 have to be taken.

6. Fire Protection

A fire extinguisher with 12 kg powder and a protection cap, for fire classification A, B,
and C according to DIN EN 3, has to be attached outside at the operation building
well visible, easy to access in case of fire, and ready for use.
For the equipment with fire extinguishers, reference is made to BGR 133 “Equipment
of Work Places with Fire Extinguishers”. Farther reaching fire protection measures
(see Exhibit 8 - Proposal For The Content of an Alarm and Danger Protection Plan)
have to be coordinated with the regionally responsible fire department.
For fire protection reasons, storage of engine oils, used oils, or other combustible
materials in quantities above 200 kg is not permitted in the CHP room. For CHPs with
up to 50 kW electrical power, the storage of up to 5,000 liters of ignition oil is
permitted.

29
Exhibit 1 Commissioning/Reoperation of a Biogas Facility
Sample for Facility according to Section 1.2
Commissioning/Reoperation of a Biogas Facility

1. During the commissioning, explosive gas mixtures may be present in the gas space in
the fermentation vessel. Spark formation has to be avoided, e.g., operation of the
stirring machines submerged.
2. Attention has to be paid to zones according to Section 3.2.
3. Initially, empty fermentation vessels have to be separated from the gas collection
system.
4. The fermentation vessels are connected to the atmosphere through over pressure
safety devices, in open position, and blow off pipes.
5. The fermentation vessels are being filled with as much as possible active substrate
until all inlets and outlets (liquid seal) are sealed by substrate.
6. Heating of the fermentation substrate.
7. During the start up/heating of the facility, no further filling shall take place.
8. During the start up of the fermentation process, the developed gases pass through the
blow off pipe (gas over pressure safety device) in the open air and replace the air in
the fermenter.
9. After verification of the gas quality, the gas system and the gas tank will be filled with
biogas. The over/under pressure safety device is put into operation. The gas quality is
sufficient and not explosive if the methane content of the gas is higher than 45% or the
gas continues to burn without ignition flame.
10. The CHPs are put into operation. They draw the gas automatically from the gas tank.
Acceptable gas quality to be verified by gas measurement.
Note: A flame test shall only be done if a flame trap is installed in front of the opening!
The opening shall not be located in enclosed rooms.

30
Exhibit 2 Test Certificate for a Biogas Foil Storage Vessel

Sample

Test Certificate for a Biogas Foil Storage Vessel

Location of Facility: Biogas Facility:

Operator of Facility:

Manufacturer of Facility:

Test Inspector for Foil

Storage Vessel:

Foil Storage Vessel

Manufacturer: Company:

Material:
Dimensions:
Gas tightness: For Methane: cm3/m2 • d • bar
Mechanical strength: Tear strength: N/5 cm
Tensile strength: N/5 cm
Temperature resistance:
Seals:
Installation type:

Tightness Test
Test area:
Test method:
Test medium:
Test result:

Remarks:

Location/Date: Seal/Signature

31
 Sample

Test Certificate for a Gas Carrying Pipe

Location of Facility: Biogas Facility:

Operator of Facility:

Manufacturer of Facility:

Test Inspector for Pipe:

Pipe in the CHP room underground

Manufacturer:
Material:
Dimensions:
Mechanical strength:
Pipe connections:
Seals:

Tightness Test
Test line from - to
Test method: According to Technical Regulations for Gas Installations
DVGW-TRGI 86 “Test of Pipes with Operational Pressure of
Up To 100 mbar”
Test pressure: Pre-Test: 1 bar, main test: 110 mbar
Test duration: Pre-Test: 10 min., main test: 10 min.
Test medium: Air
Test result:

Remarks:

Location/Date: Seal/Signature

32
Test Report No. Order No.:
VSG 1.4/BGV 2 A
Test executed according VBG 4
DIN VDE 0100 T. 610 DIN VDE 0829/EN 50 090
Reason for test: New Installation Expansion Modification Repair
Visual Inspection: Heat generating equipment Main potential equalizing
Correct selection of equipment Target destination of pipes in distributor Additional (local) potential equalization
Damage of equipment Pipe installation
Protection against direct touching Low voltage with safe switch-off
Safety devices Protection disconnector Arrangement of bus equipment in distr.
Fire protection walls Protection insulation Bus lines/actuators
Test: Remark:
Function of protection and Right orientation of 3-phase plug-ins Function of bus installation E:B
monitoring devices
Function of high voltage installation Turning direction of motors
Measurement:
Grounding resistance Ω Connectivity protective conductor/potential equalization
Insulation resistance of bus line kΩ Connectivity/polarization bus lines
Used instruments Manufacturer Type Manufacturer Type Manufacturer Type
according to
DIN VDE Manufacturer Type Manufacturer Type Manufacturer Type
Circuit Location Line/cable Over current Z8 Fault current ULS…
No. Facility part Protection Ω Protection device V
Type No. Cross Type/ /n Or R n/Art /∆mess /∆mess Umess
wires section Charac /n
2
mm t A A MΩ A A A V
Main line
Distributor

Test result: No fault Test tag at distributor Next test date

Signatures

The electrical installation corresponds to the accepted principles of electrical engineering

Inspector Responsible Operator

Location/Date Signature Location/Date Signature

33
Exhibit 3 Sample Operational Manual for a Biogas Facility in Normal Operation

Sample Operational Manual for a Biogas Facility

in Normal Operation

In addition to this sample Operational Manual, the operational instructions of the

manufacturers of individual components, such as CHP, pumps, mixers, foil storage vessels,
under pressure monitor, room air monitor, etc., are applicable.

General Part:
- Pay attention to pressure variations and to good accessibility during filling and emptying.

Daily:
- Note gas counter reading and operational hours of engine
- Verify oil level of engine
- Verify functioning of alarm lamps in the switching cabinet in the electrical room
- Verify water pressure of heating installation
- Verify the functioning of the air dosage installation of the desulphurization facility
- Monitor fermentation temperature
- Select stirring intervals so that there is no formation of a swimming or a sinking layer
- Ensure for all intakes and outlets that the liquid manure/substrate flow required by the
process is maintained
- The set up desulphurization airflow has to be adjusted to the actual gas production rate
(max. 12 vol%)
- Verify fill levels of the fermenter and the final storage
- Verify the foil connections (e.g., clamp tube at the foil gas storage vessel)

Weekly:
- Verify fill levels of the submerged cups of the over or under pressure safety device and
of the condensate separator
- Verify functioning of the submerged propeller; verify appearance of vibrations
- Visually inspect motors and electrical lines
- Verify functioning and dirt of gas magnet valves
- Verify tightness of automatically closing gas shut off valves

Monthly:
- Move all sliders several times so that they do not become stuck

6-monthly:
- Verify the air intake and outflow of the engine room of the CHP
- Inspect electrical installations for damage
- Verify functioning of the under pressure detectors
- Control function of gas sensors, fire alarm (if available)

Yearly:
- Verify all gas carrying facility parts for damage, tightness, and corrosion
- Verify fire extinguishers
34
- Verify prevention of freezing of seal liquids

In the zones according to Section 3.2, ignition sources have to be avoided, e.g.:
- Smoke, fire
- Non-explosion protected electrical equipment

Pits and Shafts

Before entering and during the stay in pits and channels, it has to be ensured that there is
no danger of poisoning, and there is sufficient air for breathing. Facility equipment has to be
safely secured against switch-on. In case of insufficient ventilation, there is the danger of
suffocation, fire, and explosion.

35
Exhibit 4 Operational Record (example)

Sample

Operational Record (example)

Date Gas Gas Con- Hours of Electricity Ferment. Substrate Mainten. Special
Meter sumption Operation Meter Temp. Supply Work Events
Reading [m3/day] [h] Reading [°C] [m3]
[m3] [kWh]

36
Exhibit 5 Sample Operational Manual for a Biogas Installation during Malfunction
Sample Operational Manual for a Biogas Installation
during Malfunction

In addition to this sample Operational Manual, the operational instructions by the

suppliers of individual components apply.
Room for Gas Storage
- Shut off gas supply
- Empty gas storage
- Access for authorized persons only
o After sufficient ventilation
o Accompanied by a second person (who stays in the vicinity of the storage opening)
and secured by a safety rope

Heating
- Attention: Danger of scalding by exiting heating water

Machine Room and CHP

- Shut off gas supply outside of machine room
- Actuate emergency switch outside of the machine room
- Possibly forced ventilation (e.g., in case of gas smell)
- If gas smell, under no circumstances use of light switches, open fire, or spark formation

Electrical Installation
- Work at the electrical installation must be done only by tradesmen

Liquid Manure Pipes and Sliders

- Remove blockages without delay
- Malfunction in the pumping system: close all sliders after pump shut-off

Pumps and Mixer

- Shut off power supply and secure against unauthorized action.
This is particularly valid for work in pre-pits and fermentation vessels!

Pits and Shafts

Attention: Before accessing and during stay in pits and channels, it has to be ensured
that no danger of suffocation and poisoning exists, and that sufficient air for breathing is
available. Facility equipment has to be secured reliably against switch-on. Sufficient
ventilation has to be ensured. In case of insufficient ventilation, there is danger of
suffocation, poisoning, fire, and explosion.

37
Exhibit 6 Shut-Off of a Biogas Installation

Shut-Off of a Biogas Installation

1. Shut-off of the substrate supply to the fermentation vessels, while removal continues.
The removal volume of the substrate may not exceed the volume of the produced gas.

2. If the removal volume of the substrate can exceed the volume of produced gas, the
fermentation vessel will be shut off from the gas collection system and the connection to
the atmosphere is established, e.g., by emptying the liquid from the liquid seal.

3. Separate the gas tank from the gas storage vessel in order to avoid gas backflow.

4. Pumps and stirring machines have to be shut off and secured against switch-on.

5. Ignition sources have to be avoided within the protection distance around the
fermentation vessel.

6. Before accessing and during stay in pits and channels, it has to be ensured that no
danger of suffocation and poisoning exists, and that sufficient air for breathing is
available. Facility equipment has to be secured reliably against switch-on. Sufficient
ventilation has to be ensured. In case of insufficient ventilation, there is danger of
suffocation, poisoning, fire, and explosion.

38
Exhibit 7 Operational Instruction

Operational Instruction
Designation of Hazardous Materials
Liquid Manure and Biogases
(Hydrogen Sulphide, Methane, Carbon dioxide, Ammonia)
Work Area: Biogas facility, liquid manure pits, liquid manure channels, liquid manure storage, channels,
etc.
Activities: Stirring, rinsing, pumping, transfer pumping, removal of liquid manure or substrate, repair and

Hazards for Man and Environment

The gases will be set free particularly by moving liquid manure or substrates. Dangerous
gas concentrations can develop that may remain for longer periods.
• Danger of life by hydrogen sulphide (H2S)
Attention: H2S disables the olfactory nerve; higher concentrations will not be noticed
any more
• Danger of suffocation by carbon dioxide (CO2)
• Danger of explosion by methane (CH4)
• Health hazard by ammonia (NH3)

Protection Measures and Rules of Conduct

Never enter the fermenter, storage areas, pits, or shafts without protection equipment.
Entry only with self-contained breathing apparatus, e.g., fresh air suction tube apparatus
with safety rope, held by at least two persons, admissible.
For work with liquid manure and substrate, any ignition source has to be avoided:
• Switch off jet gas machines
• Smoking ban
• No light test
• No welding or cutting work, sparks and welding beats may fall into pits at a distance
(if such work is absolutely necessary, attention has to be paid to good ventilation –
e.g., by a blower - pits have to be covered)

Conduct at Hazardous Situations

Entry into pits, etc., to rescue casualties only with self-contained breathing apparatus
and safety rope. Alert the Fire Department! Tel.: 112
Make sure that there is sufficient fresh air.

First Aid
After breathing of liquid manure and biogases: Fresh air supply.
Unconscious persons: Verification of breathing and stable side position.
Secure medical assistance immediately. Indicate poisoning by hydrogen sulphide.
First Aid Assistance: Doctor:
Tel.: Emergency Call: 112

__________________ ___________________________________
Date Signature Business Owner

39
Exhibit 8 Proposed Content of an Alarm and Hazard Protection Plan
Proposed Content of an Alarm and Hazard Protection Plan

A biogas facility is a construction facility that necessitates a detailed review during the
planning stage, relative to the factual assessment of the fire risk, and a close coordination
with the management of the deployment forces of the local fire department, relative to the
requirements for tactical deployment.

This requires normally the joint development of a common concept for the tactical
deployment of the fire department in case of fire incidences and for other technical
assistance (fire protection concept).

The Fire Protection Concept has to be drafted by the operator of the facility, and then
coordinated with the responsible fire department relative to their tactical requirements for
tactical deployment. The Fire Protection Concept has to be submitted in final form to the
authorization agency at least one week before commissioning of the facility.

In accordance with the individual requirements, the Fire Protection Concept will normally
have to include facts and descriptions relative to the following issues:

1. Access and transit ways, as well as positioning and operation areas for the fire
department.

2. Proof of the necessary fire water volume and proof of fire water supply.

3. Dimensions, position, and arrangements of the fire water retainers.

4. The system of outer and inner sealing in fire sectors or fire fighting sectors, as well as
the system of smoke sectors with details about positioning and arrangement of the
components.

5. Position, arrangement, and marking of rescue routes on the property and inside of
buildings, with indication of safety illumination.

6. Details of the users of the facility.

7. Position and arrangements of domestic installations, particularly pipe installations, if

case be, with details of fire behavior in the area of rescue routes.

8. Position and arrangement of air ventilation systems, if case be, with details relative to fire
protection instructions.

9. Position, arrangement, and dimensioning of smoke and heat removal installations.

10. Position, arrangement, and, if case be, dimensions of facilities, installations, and
equipment for fire fighting (e.g., fire extinguishers) with details relative to protection areas
and storage of special fire fighting matters.
40
Exhibit 9 Example of a Zoning Division

Example of a Zoning Division

(See also the collection of examples relative to explosion protection regulations [Ex-RL,
BGR 104])

Part of Facility Type of Tightness Zone 1 Zone 2

Around: Apparatus and facility parts 0 – 1 meter 1 – 3 meters

Facility parts, equipment parts, with operational gas exit
connections
------ 0 – 3 meters
Service openings and burst discs Technically tight

Permanently technically tight ------ -------

Around:
Foil storage outside 3 meters upwards

Foil covers for fermentation vessels -------- 3 meters sideways

and storage

Intake and outlet openings of smoke 2 meters downwards

tight gas storage rooms 45° inclination
Around:
Openings of blow off pipes Apparatus and facility parts 0 – 1 meter 1 – 3 meters
with operational gas exit

41
Exhibit 10 Tightness of Equipment

Tightness of Equipment

1. Tightness of Equipment

The exit of combustible gases, vapors, or dusts in hazardous quantities into the
environment can be avoided by tight equipment.

It can be distinguished between:

- Permanently technically tight equipment
- Technically tight equipment
- Equipment with operational release of combustible matters

The construction materials for equipment shall be selected for the design of equipment in a
way that they withstand the mechanical, thermal, and chemical conditions to be expected.
Danger by reaction of wall materials with combustible mixtures must be excluded. When
selecting materials, the potential for corrosion has to be considered.

1.1 Permanently Technically Tight Equipment

Equipment is permanently technically tight (BGV B6 formerly VBG 61, TRB 600 No. 5), if:

a) it is designed in a way that it remains tight because of its design, or

b) its technical tightness is continuously ensured through maintenance and monitoring.

Relative to a)

Permanently technically tight facility and equipment parts are, e.g., welded equipment with
- removable components, whereby the necessary detachable connections have only to be
operationally released very rarely, and the construction of which is designed in the same
way as the following detachable pipe connections (exception: metallically tightening
connections)
- connecting pieces for the detachable attachment of pipes, armatures, or blind covers,
whereby the necessary detachable connections have only to be operationally released
very rarely, and the construction of which is designed in the same way as the following
detachable pipe connections (exception: metallically tightening connections)

Permanently technically tight pipe connections are, e.g.:

- non-detachable connections, e.g., welded
- detachable connections, which operationally are very rarely detached, e.g.:
o professional flange connections

Permanently technically tight connections for the connection of equipment, as far as they
are rarely operationally detached, are, e.g.:
- pipe connections as mentioned above, and

42
- NPT-thread (National Pipe Paper Thread, cone type pipe thread) or other conical pipe
threads with sealing the thread until DN 50, as far as they are not exposed to changing
thermal loads (∆t > 100 °C).

Relative to b)

Beside pure design measures, technical measures combined with organizational measures
can also lead to permanently technically tight equipment.

This category includes, e.g., with appropriate monitoring and maintenance:

- Dynamically loaded seals, e.g., for axle guides of pumps
- Thermally loaded seals of facility parts

The extent and frequency of verification and maintenance depend in detail on the type of
design, operational mode, and the loads and shall ensure permanent technical tightness.
Attention has to be paid that extent and frequency of verification and maintenance,
necessary to maintain permanent technical tightness, shall be determined in the operational
instructions.

For the verification, one of the following measures can be sufficient:

- Walk through and observation, e.g., for streaks, formation of ice, smell, and noise
caused by leakages.
- Walk through the facility with mobile leak detectors or mobile gas warning equipment.
- Continuous or periodic monitoring of the atmosphere by automatic fixed measurement
equipment with warning function.

Suitable preventive maintenance can reduce the extent and frequency of the verification of
tightness.

1.2 Technically Tight Equipment

Equipment is technically tight if during a tightness test or tightness monitoring or control no

leakage is detectable, e.g., by means of foam generating means or with leakage test or
display instruments, whereby rare releases of gases and vapors cannot be excluded, for
example:

- Pumps whose technical tightness cannot be ensured permanently (e.g., with a simple
sliding ring seal.
- Detachable connections according to Item 1.1, which are rarely not detached.

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Exhibit 11 Examples of Further Requirements and Regulations
Examples of Further Requirements and Regulations

Accident Prevention Regulations (VSGen) of the Agricultural Cooperative Associations

VSG 1.1 “General Regulation for Occupational Health and Safety”

VSG 1.4 “Electrical Facilities and Equipment”
VSG 2.1 “Work Locations, Construction Facilities, and Equipment”
VSG 2.2 “Storage Sites”
VSG 2.8 “Liquid Manure Storage, Pits, Channels, and Wells”

Source for ordering: The VSWGen can be requested from the proper Agricultural
Cooperative Association (see second to last page).

Ordinances:
Ordinance for safety and occupational health relative to the appropriation of means for work
and their use for work, relative to the safety during operation of facilities which have to be
monitored during operation, and relative to the organization of operative occupational health
and safety (Operational Safety Ordinance – BetrSichV).

Ordinance of the Ministry of Environment and Traffic relative to handling of water

endangering materials and relative to specialized operations (Ordinance for Facilities with
Water Endangering Materials – VawS) in the edition by the different states.

Ordinance for Storage of Water Endangering Materials (March 2001)

Regulations by the Professional Liability Insurance Associations:

BGV C 5 “Technical Waste Water Facilities”

BGV D 2 “Work on Gas Pipes”
BGR 104 “Explosion Protection – Rules”
BGR 133 “Equipment of Workplaces with Fire Extinguishers”

Source for ordering: Carl Heymanns Verlag KG

Luxemburger Str. 449
50939 Köln/Germany

DIN Standards (Norms)

DIN 2403 “Marking of Pipes According to the Flow Matters”

DIN 2470 (1) “Gas Pipes of Steel Tubes with Permitted Operational Pressures Up To 16
Bar; Requirements for Pipe Parts”
DIN 3380 “Gas Pressure Regulators for Entry Pressures Up To 100 Bar”
DIN 4102 “Fire characteristics of construction materials and construction parts”
DIN V 19250 “Control Equipment; Basic Safety Considerations for MSR Protection Devices”
Source for ordering: Beuth Verlag, Burggrafenstr. 6, 12623 Berlin, Germany
VDE Regulations
44
DIN VDE 0100 “Establishment of High Power Installations with Nominal
Voltages Up To 1000 V”
VDE 0165 Part1/
EN 60 079-14 “ElectricalEquipment for Gas Explosive Areas – Part 14:
Electrical Installations in Gas Explosive Areas (except mines)”

VDE 0170/0171 “Electrical Equipment for Explosive Areas”

DIN 57 185/VDE 0185 “Lightning Protection Installation”

DIN/VDE 2180 Part 1 Safety of Installations of Process Engineering by Means of

Process Control Engineering (PLT) – Introduction, Definitions,
Descriptions

DIN/VDE 2180 Part 3 Safety of Installations of Process Engineering by Means of

Process Control Engineering (PLT) – Construction and
Installation Measures to Secure Functioning of the PLT
Installation in Emergency Situations

DIN/VDE 2180 Part 4 Safety of Installations of Process Engineering by Means of

Process Control Engineering (PLT) – Calculation Methods for
Reliability Characteristics of PLT Safety Installations

DIN/VDE 2180 Part 5 Safety of Installations of Process Engineering by Means of

Process Control Engineering (PLT) – Use of Safety Oriented
Programmable Controls

Source for ordering: VDE-Verlag GmbH, Bismarckstr.33, 10625 Berlin, Germany

DVGW-Regulations

G 600 “Technical Rules for Gas Installations DVGW-TRGI 1986/1996”

G 262 “Use of Landfill, Sewage, and Biogases”

G 472 “Polyethylene Gas Pipes Up To 10 Bar Operational Pressure (RE 80,

PE 100 and PE-Xa) – Installation”

G 469 “Pressure Test Method for Pipes and Installations of Gas Supply”

G 462 Part 1 “Installation of Steel Gas Pipes Up To 4 Bar Operational Over

Pressure”

G 462 Part 2 “Steel Gas Pipes from 4 Bar to 16 Bar Operational Pressure;
Installation”

Source for ordering: Wirtschafts- und Verlagsgesellschaft Gas und Wasser mbH,
45
 Postfach 14 01 51, 53111 Bonn, Germany

Masthead

Editor:

Federal Association of Agricultural Cooperative Associations (BLB)

Reference: Through the regional Agricultural Cooperative Associations, see (next page)
addresses

Print run: 3735

Production: Printing Plant Schanze GmbH, Kassel, Germany

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List of Agricultural Cooperative Associations

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