What causes dust to become “combustible?”
Virtually any inorganic material that can oxidize (rust) is capable of generating a dust explosion. Coal, sawdust and magnesium for instance. Many otherwise harmless materials can also lead to a combustible dust cloud: grain, flour, sugar, powdered milk and even concentrated pollen. And powdered metals, such as aluminum and titanium can form these explosive dust suspensions in an enclosed environment.
A combustible dust hazard occurs when the airborne particles of any potentially flammable compound in sufficient quantity, contact any source of ignition. The spark of metal on metal, an electric arc from machinery or even a static electric charge can ignite airborne dust particles of certain densities. This initial blast can reach massive temperatures nearing 3500 degrees Fahrenheit and incinerate unprotected clothing, setting it ablaze and causing serious injury and even death.
Who is at risk from a combustible dust hazard?
Workers and even casual visitors to areas such as coal mines, grain elevators, flour mills and metal fabricator facilities are at risk from combustible dust. But the list is not limited to these. Many facilities that merely transport or store materials that otherwise would not be explosive, are at risk when improper ventilation or mechanical failure allow oxidized and airborne particles to concentrate in confined spaces. Even if a dust “cloud” is not visible, workers may be at risk from combustible dust that is present in a sufficient quantity to ignite.
How do you protect your workers from the hazard of combustible dust?
Helpful link: OSHA Combustible Dust NEP