The presence of combustible dust in the work environment is a very real danger. Five elements need to be present for a dust explosion to occur: combustible dust, oxygen, dispersion of dust particles in a confined space, and an ignition source. When all of these conditions are met, a dust explosion can occur.
Although dust explosions can be a real danger, they are also preventable. It’s important for you to know if you have a combustible dust hazard in your workplace. Safety standards for the prevention of combustible dust hazards are available and fines could be levied if employees are not wearing protective flame-resistant clothing.
Here are some of the most dangerous characteristics of combustible dust and why dust explosions are so dangerous:
Dust explosions can be fatal.
A dust explosion occurs when a finely divided combustible materials reach a certain airborne density and touch an ignition source (such as a flame or spark). While it may seem unlikely that such a combination of perfect conditions will occur, according to the Center for Public Integrity, combustible dust has killed or injured over 900 workers across 450 accidents since 1980.
Combustible dust can be insidious
In many cases, the dust particles accumulated on surfaces slowly and went unnoticed for long periods of time until the conditions for a dust explosion were met. That is what happened at the Hoeganaes Corporation metal powder plant near Nashville, TN when a small dust explosion killed two employees in 2011. In the case of Hoeganaes, a small electrical wire laid exposed next to a bucket elevator that carried dust through the plant. This shows that the ignition source required for a potentially fatal dust explosion can be very small.
The most common materials involved in dust explosions are wood, metal, food, plastics, and coal. Materials that seem relatively harmless in dust form such as flour, paper, dyes, and spices can be catalyst to dust explosions in the right setting.
Dust explosions happen instantly
Dust can be ignited by open flame, hot surfaces, friction, electrostatic discharges, arc flashes, and other non-flame sources. Even static electricity has been linked as a source of dust explosions. Whatever the ignition source, dust combusts rapidly causing severe damage and injury in seconds. The most severe burns are caused by the ignited clothing, not by the original explosion itself. Wearing FR clothing can help to minimize the burn injuries of dust explosions.
Dust explosions propagate
Once the initial explosion occurs, there is a threat of another explosion called the “secondary explosion.” The force of the first explosion disperses settled dust in the area into the air. These chain reactions can cause very large flammable dust cloud explosions causing widespread damage.
Learning how to identify a dust hazard, implement proper safety measures, and monitor the situation is the best way to prevent a possible dust explosion. The more you know about possible hazards the better able you are to protect workers from an incident.