WHY IS A DUST EXTRACTION SYSTEM DESIGNED ACCORDING TO THE ATEX DIRECTIVES THE ONLY RIGHT CHOICE?
Explosion in a dust extraction system can have a huge negative impact on your business, forcing you to shut down production for a long time. Choosing a correctly designed system with the right equipment is your best insurance as you minimize the risk of explosion immensely.
Our Documentation & QA Manager, safety expert and member of the National Committee DS–S 531, Carsten Hembo, explains in detail below how a dust extraction system should be designed.
Prevent Ignition Sources Inside the Dust Collector
In the EU, manufacturers of ATEX directive-compliant baghouse dust collectors must ensure that the filters have no own ignition sources during normal operation and malfunctions. This requires in-depth knowledge and understanding of how the different system components work.
– In practice we ensure a safe design without own ignition sources by assessing the different components inside the filter, using antistatic filter bags, internal equipotential bonding and only using components certified for the actual dust concentration, Safety & QA Manager at Moldow, Carsten Hembo, explains.
– Everything has been done in close cooperation with a Notified Body, who has validated that our safe design lives up to all applicable legislation and standards
External Ignition Sources
Although preventing ignition sources inside the baghouse filter has huge importance for explosion safety, the explosion risk cannot be eliminated completely, as an external ignition source can enter the filter and ignite the dust.
– An external ignition source can for example be a spark from a processing machine that travels through the ducts to the filter. That is why it can be a good idea to include a spark detection and extinguishing system which can prevent an explosion due to an external ignition source, Safety & QA Manager at Moldow, Carsten Hembo, explains.
Explosion Venting on ATEX Dust Extraction System – a False Sense of Security?
Taking the above-mentioned precautions, the explosion risk is minimal. But should an explosion occur, Moldow baghouse filters are equipped with explosion venting, which prevents a demolition of the filter unit and an uncontrolled explosion relief.
– Filters from Moldow have been full-scale explosion tested by a Notified Body, which is why we can guarantee that our baghouse filters meet the highest safety requirements, and that a possible explosion will be relieved safely.
– So instead of forcing you to shut down production for a long time and invest in a new filter, your dust extraction system should, in the majority of cases, be ready for operation again after only installing new filter bags and explosion venting.
– Unfortunately, some filters do not live up to applicable legislation. Even though they have explosion venting or an Ex sign, they might not have been designed properly or tested by a Notified Body. This will give a false sense of security, as you would think that the system is explosion safe, Carsten Hembo points out.
Surprisingly Many Dust Explosions
Do explosions still happen? Unfortunately, yes. In 2019, 75 combustible dust explosions were registered globally resulting in 118 injuries and 8 fatalities.
– The ATEX directives have been in force since 2003. Since then more and more countries outside the EU have become aware of the requirements and content of these Directives, including the requirement to carry out an Explosion Risk Assessment, Carsten Hembo points out.
– As the latest addition, the American authorities have made NFPA 652 mandatory for all companies handling combustible dust. It is required to carry out a Dust Hazard Analysis (DHA) no later than September 7, 2020.
