In NFPA 660, section 9.8.2.4, it states where both an explosion and fire hazard exist, protection for both hazards need to be employed. If I have a dust collector pulling dry dust out of an air exhaust stream from a process that does not have any flammable vapors, do I only have the dust explosion risk to consider? My understanding is that since any dust combustion hazard (i.e. flash fire or true deflegration) requires dispersion, a pile of powder sitting in the dust collector when it is idle is not a fire risk like a pool of flammable liquid would be. The dusts I am working with are various organic materials, typically considered St 2 materials.
Yes, sounds that way to me.