Biogas Safety first!

Specific requirements
or coated products rather than powdered products),
and this must be documented. Appropriate measures
must be taken to avoid the open handling of additives
and auxiliary materials. Employees’ exposure to additives
and auxiliary materials must be avoided or at
least reduced to the minimum achievable through
technical and organisational measures.
The following types of work with additives and auxiliary
materials are most likely to present hazards:
1. visual inspection of packaging for damage,
acceptance check
2. unloading from delivery vehicle, transport
within the plant, placing in storage
3. removal from storage, making ready for use,
putting to use
4. removal of impurities
5. performance of maintenance work, e.g.
on the metering system
6. disposal or return of packaging
Classification of Ex zones
If a tubular screw conveyor system to feed input materials
is installed below the surface of the liquid in
the digester, the following requirements must be met:
limitation of the removal flow rate and daily
checking of the fill level, or
if the fill level falls below a minimum limit, an
alarm is automatically triggered and removal
is shut down so that the system remains safely
below the level of the liquid.
No zoning necessary, unless the manufacturer’s
instructions specify different classification of
zones.
In the case of liquid feeding systems (silage diluted
with liquid feedstock to make it pumpable) the possibility
of a hazardous potentially explosive atmosphere
being formed cannot be ruled out. Additional
explosion protection measures (ventilation, monitoring
of CH 4
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
If rotating parts are used, they must be designed in
such way that technical measures (e.g. a protective
cover) prevent people from reaching in, being pulled
in or falling in.
Classification of Ex zones
→ See Ex zone classification for holding
tanks / digester preliminary pits (see section 3)
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 manufacturers
and distributors must be heeded. When using
substances that pose a risk to health (e.g. trace elements),
ensure that they are stored and metered in
closed systems to minimise emissions.
Preliminary pit
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