A powder coating booth is not a paint booth with different material in it. Wet spray creates a flammable vapor hazard. Powder coating creates a combustible dust hazard, and combustible dust behaves in a way that flammable vapor does not: suspended in the right concentration and given an ignition source, it deflagrates. The pressure rise from a dust deflagration inside an enclosure or a recovery duct is a structural event, not just a fire.
That difference drives everything about how these installations are protected. The dominant ignition source is not open flame but electrostatic discharge, generated by the same charging process that makes powder coating work in the first place. Ungrounded parts, an unbonded booth panel, or an isolated conductive object inside the recovery system can accumulate enough charge to produce a spark in a dust cloud that is already at explosive concentration.
The other half of the hazard is accumulation. Powder that settles on horizontal surfaces, inside the recovery cyclone, in the duct run, and on top of the cure oven is a secondary explosion fuel load. Most catastrophic dust incidents are not the initial event but the secondary deflagration when the first pressure wave lifts settled dust into suspension. Housekeeping is a fire protection control at these facilities.