Overview
- Composition of the dust
- Particle size
- Processes being used
- Accumulation of more than 1/8”
Combustible dust is an area of focus from both OSHA and the National Fire Protection Association due to the potential for fires and explosions. Combustible dust explosions have occurred in the following types of operations: manufacturing, printing shops, agricultural operations such as feed and grain mills and bins, fertilizer plants, and wood and metal shops.
At UNL, some research is being done using different forms of plant starches which are extremely fine in size and can present the same hazards as wood or metal dust if not properly managed. In the photos provided, not only was the interior of the room coated with a layer of dust but the accumulation inside the air handling unit was over two inches thick.
All different types of commonly found products if present in the proper form and size are considered to be “combustible”. Flour, spices, powdered milk, cornstarch, charcoal, wood or sawdust, cotton, cellulose, sulfur, magnesium and a variety of plastics. The size of the particle isn’t defined from an OSHA perspective but usually considered to be finer than 420 microns.
Please note that a follow-up will be conducted by the assigned EHS staff person if you see fine dust in gross horizontal accumulations (over 5% of the room’s sq. ft.) of over 1/8” or the thickness of a dime on countertops, electrical fixtures or overhead on structural steel or pipe runs.
If you are unfamiliar with this topic you may want to watch a very informative video from the U.S. Chemical Safety Board that explains and demonstrates the actual hazards of combustible dust.