Workplace safety update
Combustible dust: Preventing dust explosions Combustible dust is made up of fine solid particles that can catch fire or explode when dispersed in air and exposed to an ignition source. Larger particles settle, while smaller particles can remain suspended. Dust can be generated by handling, crushing, grinding, or processing materials, including:
• Most solid organic materials (such as sugar, flour, grain, wood, etc.)
• Many metals (including magnesium, aluminum, and bronze)
• Some nonmetallic inorganic materials
Some of these materials aren’t “normally” combustible, but they can burn or explode if the particles are the right size and in the right concentration. As a rule of thumb, more than 1/32 of an inch of dust (about the thickness of a paperclip) over a large area increases risk. A combination of housekeeping, ventilation, and dust collection keeps accumulation under control.
Combustible dust is dangerous and a silent killer, and it lurks in unseen places, such as rafters, the tops of hoods, and ductwork. All it takes is a handful of fine dust in the air, a contained area, and an ignition source to create a potentially deadly environment.
Many dusts are combustible if conditions are “right.” Elements needed for a typical fire are fuel, heat, and oxygen. A dust explosion requires two additional elements: dispersion of the dust into the air and confinement within an enclosure (the dust explosion pentagon). Removing any one of these elements prevents an explosion.
Additionally, the particles have to be close enough together so that the flame can spread rapidly between them. Wood dust, for example, doesn’t need to be as fine as coal dust.
Be alert for signs that combustible dust may be present. Regular monitoring and removal of dust needs to be done not only in primary areas where dust accumulates, such as on production floors, but also in secondary areas that include cable trays, ductwork, and false ceilings, as well as behind equipment and in other hidden areas.
Three basic principles should be applied to prevent dust explosions:
- Keep dust out of the air as much as possible.
- Keep dust cleaned up.
- Keep sources of ignition away.
Learn More: Employee Safety Update for April 2025