Explosion prevention and explosion protection according to ATEX

Fire protection is not covered by ATEX guidelines


In contrast to explosion protection, fire protection is not clearly regulated by law.

This is why the operator should determine the extent of general or specific fire protection measures and the application of rules.

DIN EN 13478
Machine safety – fire protection

VDI 2263 page 6
Dust fires and explosion protection in dust extraction installations

VDS 3445
Fire protection in dust extraction installations

Latent fire hazard in dust extraction installations


Dust extracting installations with mostly dry filtration technology are especially at risk. Dust explosions can lead to fire. This possibility should be considered for all protection systems.

Dust fires can also occur without explosions.

Undetected dust accumulations can ignite from an increase in heat and lead to smoldering fires or the occurrence of flames.

Flammable materials must be given particular consideration.

Even slightly smoldering fires in the ductwork or in a filter element rarely go out since they are always fanned by high air volumes in the dust extraction system.

Smoldering fires and flames can create a latent ignition source for dust explosions.

Metallic dusts in particular often result in damage


Our experience indicates that metallic dusts are twice as flammable as organic dusts.

This warning is supported by impartial industry-wide testing. Spark entry and spontaneous combustion were cited as the most frequent sources of ignition.

Ignition sources basically correspond to explosion sources.

An in-depth overview is provided in the GESTIS-DST-EX database.


GESTIS-STAUB-EX
>

Organizational measures


The operator is responsible for the safety of the system.

According to applicable German laws (ArbSchG, BetrSichV, GefStoffV etc), the hazard evaluation must be reported.

The process parameters must also be checked for alterations in the design and the adherence to the intended use. If necessary, corresponding measures must be adopted.

 

Following measures must be undertaken if a fire risk cannot be excluded:

– Only trained, authorized personnel may operate the dust extracting machine

– The operating personnel must be familiar with all operating conditions, especially with potential deviations from the normal operation. It shall be informed on the installed fire protection systems and the requirements in case of fires.

– The fire brigade must be informed on the possible risk of fire in the dust extraction system and installed fire protection measures.
The procedures in the event of fires should also be coordinated.

Operating instructions

Following measures shall be taken into account in the instruction manual:

– Strict ban on smoking in fire and explosion endangered areas.

– Prevention of the entry of ignition sources such as cigarette butts and easily combustible materials (such as cleaning rags)

– The dust collection tank must be emptied continuously according to the volume of dust.

– Dust accumulation must be avoided.

– Labor with sources of heat may only be performed with necessary precautionary measures (including VdS 2008 "Welding-, cutting,- soldering- and metal cutting").

– Inspection and maintenance must be performed and documented according to the manufacturer’s instructions.

Fire protection design B

(mechanical/ organizational)

Fire protection by mechanical and organizational measures to avoid fires can be ensured in dust extracting systems of design B.

Measures
Spark pre-separator
(at machine tools)

Spark detection

Spark extinguishing

Grounding

Heavy non-combustible filter

Fire protection design C

(damage limiting)

Measures

Interruption of the dirty air supply for the cleaning process in the dust extraction system.

Fire detection on the dirty air side by maximum heat sensor.

Fire detection on the dirty air side by maximum heat sensor or visual smoke detector, in ductwork by spark detector.

Manual extinguishing/semi-stationary extinguishing system for water extinguishing.

Manual extinguishing with powder or gas with extinguishing access opening in dust extraction system (e. g. TR-1)





For this layout, measures for damage limitation are of particular importance, as a supplement to fire prevention measures:

Automatic stationary extinguishing system for CO2 extinguishing (incl. extinguishing agent tank) sensor technology.

Shut off valves with actuators or pneumatically activated on the dirty air side, closing securely with 3 % opening on the clean air side.

Legal measures:
e. g. authorization to operate the dust extraction system

Assistance in selection
of fire protection measures (PDF)

Explain thorough and cautious behavior


Even the peripheral areas of dust extraction systems are of significance during fire protection. The dispersion of relatively small dust accumulations can lead to an explosive environment.

For central dust extraction systems, it is important to consider flame breakthrough in various fire sections during the planning.