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Beware the Dust Explosion Triangle

Originally published by Chris Kilbourne on http://safetydailyadvisor.blr.com

It’s just dust. How could it be that dangerous? Because any combustible material (and some materials normally considered noncombustible) can burn rapidly when in a particular or finely ground form.

In simple terms, a dust explosion is a very rapid combustion or burning of the dust when it is suspended in air. In addition to the familiar fire “triangle” of oxygen, heat, and fuel (the dust), dispersion of dust particles in sufficient quantity and concentration can cause rapid combustion known as a deflagration.

If the event is confined by an enclosure such as a building, room, vessel, or process equipment, the resulting pressure rise may cause an explosion.

All of the following five factors create the “Dust Explosion Pentagon”:

  • Oxygen
  • Heat
  • Fuel
  • Dispersion
  • Confinement

If one element of the pentagon is missing, an explosion cannot occur.

Fire and explosion from combustible dust pose immediate and deadly risks to health and safety. In fact, dust explosions are routinely catastrophic in nature, resulting in loss of lives and severe structural damage, and are often devastating to the community.

Secondary Explosions

Secondary explosions, which are relatively common after dust explosions, make the hazards that much worse. The initial explosion dislodges more accumulated dust into the air or damages a containment system such as a duct, vessel, or collector, again releasing more dust. As a result, if ignited, the additional dust dispersed into the air may cause one or more secondary explosions.

These can be far more destructive than the primary explosion because of the increased quantity and concentration of dispersed combustible dust. Many deaths and extensive damage in past accidents have been caused by secondary explosions.

In many dust explosions, employers and employees were unaware that a hazard even existed. Ignorance of combustible dust hazards can be fatal. If your company is potentially affected by these hazards, please take action now to prevent tragic consequences.

Don’t Wait for an Explosion!

The force from a combustible dust explosion can cause employee deaths and injuries, and the destruction of entire buildings.

  • The U.S. Chemical Safety and Hazard Investigation Board (CSB) identified 281 combustible dust incidents between 1980 and 2005 that led to the deaths of 119 workers, injured 718, and extensively damaged numerous industrial facilities.
  • More recently 3 workers were killed in a 2010 titanium dust explosion in West Virginia and 14 were killed in a 2008 sugar dust explosion in Georgia.

A wide variety of materials that can explode in dust form exist in many industries.

Because of the risks, OSHA turned the spotlight on combustible dust hazards with a National Emphasis Program. The agency also included combustible dust in its definition of a hazardous chemical when it revised the hazard communication standard to align with the requirements of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS).

Combustible dust is an innocent-looking disaster waiting to happen. Everyone in your workplace should be aware of this potential hazard and should take every precaution to be sure that your workplace stays safe from sudden explosions and the other hazards of combustible dust.