WHAT CAUSES A DUST EXPLOSION?
Like flammable gas, flammable dust needs to mix with air and encounter a source of ignition to explode. Flammable dust has been a problem in underground coal mining for many years. Mining experts did much of the research on dust explosion hazards, as well as much of the early work on flammable gas hazards. The U.S. Bureau of Mines performed research on dust ignition properties. It even built a simulated coal mine tunnel it could fill with dust and air and ignited it to study the properties of dust explosions. This research helped determine how much energy it took to ignite a cloud of a particular dust mixed with air and provided data on how a dust explosion propagates. Ignition can happen two ways: by spark energy or by a hot surface. Each type of dust has a particular ignition energy and an autoignition temperature—the temperature a hot surface has to reach to set off a dust/air cloud. The National Fire Protection Association (NFPA) publishes a standard, NFPA 499, that lists these pro
