06/03/2022
Grain dust Explosion....
Over the last ten years, grain dust explosions have occurred at an average of 10 explosions per year. You might look at that number and think that grain dust explosions aren't something you need to worry about. However, the magnitude of these explosions can be devastating. These explosions can bring down entire operations, causing injuries and even fatalities. But with prevention, grain dust explosions can be avoided.
What is a Grain Dust Explosion?
When grain is handled, dust particles are created. Some of these particles will be fugitive dust, which are very small dust particles that escape into the atmosphere and are suspended in air. It collects on floors, ledges, beams and any exposed equipment. Grain dust explosions happen when there is an accumulation of grain dust in the air and on equipment in a confined space and then exposed to an ignition source.
There are five elements that must be present for an explosion to occur: grain dust, oxygen, dispersion of dust, confinement, and an ignition or fuel source. This is sometimes referred to this as the dust explosion pentagon. If any one of the five elements are removed, an explosion cannot take place.
There are two phases to the explosion, primary and secondary. The primary explosion usually occurs within a confined area, such as the bucket elevator or conveyor. If the dust is exposed to a heat source, it ignites and causes the explosion. The blast from the primary explosion dislodges and suspends the fugitive dust which causes the secondary explosions (see illustration below). These explosions are normally much larger and more catastrophic. The five elements of the explosion pentagon must be present for both the first blast and second blasts.