Combustible dust is basically any ultrafine material which can ignite and explode once combined with air. It is not given its due as it happens more often than is realized. Built-up dust, even in minute amounts, can cause extensive damage.
What is Combustible dust
The Occupational Safety and Health Administration (OSHA) defines combustible dust as the following, “Combustible dusts are fine particles that present an explosion hazard when suspended in air in certain conditions.”
That being said, the vast majority of natural and synthetic materials, including some metals, can create combustible dusts. This often overlooked potential hazard is more common than you may think, and yet combustible dust explosions, accompanied by fires, are often one of the most ignored risks in the workplace.
Five critical factors must be in place for ignition to occur. The first three are the obvious – heat, fuel (in this case the dust), and oxygen, known as the “fire triangle.” Distribution of particles, in ample quantity and concentration, can cause rapid ignition defined as deflagration. However, two additional factors added to the “fire triangle”, dispersion and confinement, create what is known as the “dust explosion pentagon.” This amalgam of conditions and factors can lead to a catastrophic explosion. However, if but one of these factors is not in place, there cannot be an explosion.
There does exist an additional threat should a primary explosion occur. If there are additional dust particles dislodged after the initial explosion, the primary explosion could ignite a secondary, more powerful explosion, which is often more catastrophic and more often results in the loss of life, injury, as well as physical building damage.
Sited in A Guide to Combustible Dusts, the North Carolina Department of Labor, in collaboration with OSHA and Commissioner of Labor, Cherie Killian Berry, OSHA State Plan Designee, many natural and synthetic organic materials in many of today’s manufacturing processes can contribute to the formation of combustible dust. They are as follows:
- Food products (e.g., grain, cellulose, powdered milk, sugar, flour, starch, cocoa, maltodextrin)
- Pharmaceuticals (e.g., vitamins)
- Wood (e.g., wood dust, wood flour )
- Textiles (e.g., cotton dust, nylon dust)
- Plastics (e.g., phenolics, polypropylene)
- Resins (e.g., lacquer, phenol-formaldehyde)
- Biosolids (dried wastes from sewage treatment plants)
- Coal and other carbon dusts
Combustible dusts can also be formed from inorganic materials and metals including:
- Magnesium powder
These are but a few, with almost every facet of our modern industrial society prone to this destructive phenomenon.
Prevention of Dust Explosions
To keep this insidious hazard from occurring, OSHA recommends following some precautionary rules of thumb to aid in the prevention of an explosion. Steps to help lessen the probability of a, combustible dust explosions could begin with examining the processes in place at many manufacturing facilities which use any of the materials listed above in their production processes that could produce dust particles.
Another important precaution would be noting the presence of ignition sources such as, flames, sparks, hot machinery, stoves, welding arcs, etc. The areas surrounding these sources should be free of accumulated dust, especially in hard to see, confined areas.
Housekeeping, in general, is another area of concern. Is there a housekeeping schedule to regularly remove dust? Is there a dust collection system in place and in good working order, and does it conform to local fire code requirements?
Regular, scheduled cleaning of hoods, air ducts and vents, as well as unseen accumulation areas, is the preeminent measure for safety. HVAC is the most reliable way to remove most traces of fine particulate dust.
Be sure to have your HVAC Ducts and Vents Thoroughly Cleaned
Knowledge and prevention are key to understanding the potential hazards associated with this paradox. For commercial combustible dust cleaning and control, contact Preferred Hood & Duct, Inc.. For questions and to find out more information, fill out our online form, or contact us directly at (860) 613-1130.