Choosing explosion prevention and isolation equipment for your dust collection system — Part II
Combustible dust hazards and explosion safety have become increasingly urgent concerns in bulk solids processing and handling plants. In this two-part article, a dust collection expert expands on Powder and Bulk Engineering's recent coverage of these issues by providing information on how to prevent explosions in dust collection systems and how to isolate the connected bulk solids process from a dust collector explosion. Part I appeared in October.
If a deflagration occurs in your dust collector, a pressure wave and flame front will propagate through the ductwork to upstream and downstream equipment even if the dust concentration in your ductwork doesn't exceed the dust's MEC. The flame front is a serious hazard to anyone working near the dust capture hoods. If the ductwork's dust concentration does exceed the MEC, the deflagration will propagate through the duct and cause pressure piling (that is, the pressure wave ahead of the flame front will add to the pressure in the connected equipment). This pressure piling can exceed the explosion protection capability of the downstream equipment -- such as a cyclone -- and cause it to fail. You can prevent this by using an explosion isolation device in the duct, which will confine the explosion to the collector and block it from propagating to upstream and downstream equipment.