Prevent combustible dust explosions

Combustible dusts – finely ground organic or metal particles – can be found in a number of industries, the Washington State Department of Labor and Industries states. These industries include food, tobacco, plastics, paper, rubber, textiles, pesticides, pharmaceuticals and fossil fuel power generation.

Washington L&I notes that combustible dust can accumulate inside of, or escape from, equipment and settle on work area surfaces. These accumulations, when dispersed in the air in the presence of an ignition source, can result in an explosion.

OSHA says five elements must be present for a dust explosion to occur. If any one of these elements is missing, an explosion will not occur.

The first three elements are needed for a fire:

1. Combustible dust (fuel)
2. Ignition source (heat)
3. Oxygen in air (oxidizer)

The other two elements that must be present for a combustible dust explosion to occur are:

4. Dispersion of dust particles in sufficient quantity and concentration
5. Confinement of the dust cloud

To prevent a dust explosion, OSHA recommends employers:

• Implement a hazardous dust inspection, testing, housekeeping and control program.
• Use proper dust collection systems.
• Regularly inspect for dust residues in open and hidden areas.
• If ignition sources are present, use cleaning methods that do not generate dust clouds.
• Control smoking, open flames and sparks, including mechanical sparks and friction.