Combustible Dust

 

   
 Continuous Combustible Dust Remediation

    

The Deadly Dangers of Combustible Dust

In Mississippi, a rubber fabricating plant suffered a dust explosion that killed five and injured 11. Wood dust in a Pennsylvania particleboard plant exploded killing three and injuring 10. In North Carolina, plastic powder used at a pharmaceutical plant caused an explosion that killed six and injured 38. A series of wheat dust explosions in a grain storage facility in Kansas killed seven. At a wheel manufacturing plant in Indiana, explosions of accumulated aluminum dust severely burned three employees–one fatally. And in 2008, a series of dust explosions and fire at a sugar plant in Georgia killed 14 and injured 36.1

The list could go on and would include many different types of combustible dust present in a wide range of industries. According to OSHA and the U.S. Department of Labor, since 1980 there have been at least 350 combustible dust explosions in the United States, killing more than 130 workers and injuring almost 800. In many accidents, employers and employees were unaware that a hazard even existed.1

What Makes Dust Combustible?

Part of the problem with regulating dust explosions is the confusion about which dusts can explode andunder what conditions.2

 A large number of solid substances become explosive when in the form of a fine dust. These substances include organic materials, such as grain, sugar, wood, and coal; synthetic organics, such as plastics, dyes, foams, pharmaceuticals, and chemicals; and combustible metals, such as aluminum, magnesium, zinc, and iron. Generally speaking, the smaller the dust particle, the bigger the hazard. 2

Five conditions raise the risk of a dust explosion. If a combustible dust is suspended in air or another oxidizing medium, is at the minimum exposable concentration (MEC), is in the presence of an ignition source, and is confined, the conditions are ripe for a dust explosion. Removing at least one element of the dust pentagon is the control strategy in NFPA dust standards.2

 

 

Subsequent explosions, or secondary explosions, often occur once dust is disturbed. It was secondary dust explosions, which are due to inadequate housekeeping and excessive dust accumulations, which caused much of the damage and casualties in recent catastrophic incidents.3

 

Is Your Facility at Risk?

OSHA estimates at least 30,000 U.S. facilities and hundreds of types of processes may be at risk for a combustible dust incident. Those industries include food, grain, tobacco, plastics, wood, paper, pulp, rubber, furniture, textiles, pesticides, pharmaceuticals, dyes, coal, metals, and more. By recent estimates, on average two to three dust explosions occur in various manufacturing facilities in the United States every day. In addition to the potential loss of life and injury, a single incident can cost millions in damage, large fines from OSHA, and shut a facility down for months—if not permanently.1

Explosions can happen in any manufacturing process or facility where combustible dust is produced—in the air, stored, or accumulated. The National Fire Protection Association (NFPA) currently states that dust accumulations of as little as 1/32 of an inch (approximately the same thickness as a paper clip) are sufficient to create a dust deflagration when dispersed and exposed to an ignition source. Employee safety is threatened by the initial explosion, ensuing fires, additional explosions, flying debris, and collapsing building components. Recognizing unsafe conditions and then doing something about them can break the chain of events that could lead to a dust explosion and its catastrophic results.1

 

1. Pederson, Neils H., Avoiding Combustible Dust Explosions, article from Powder Bulk Solids May 2010.

2. Spencer, Amy Beasley, When a Nuisance Becomes Deadly, NFPA Journal, November/December 2008.

3. Condello, Albert V. III,   Professor, Safety Mgmt & Fire Protection Engineering, Department of Engineering Technology, University of  Houston.


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