Fires and explosions are a serious safety concern for food processing facilities, especially those working with dry powdered ingredients. An effective dust collection system is an essential element of plant safety—and also one of your biggest fire and explosion risks. Here’s what food processors should know about dust collector safety, National Fire Prevention Association (NFPA) compliance and safe system design.
How Dust Collector Fires and Explosions Occur
According to dustsafetyscience.com, dust collectors are responsible for nearly 15% of industrial fires and explosions in North America, resulting in 25 fires and four explosions in 2021 alone. Many of these were in the food and bakery industries.
The food industry is at high risk for dust collector fires and explosions due to the nature of the dust being collected. Dry, powdered organic materials such as sugar, flour, starch, cocoa, dehydrated milk products, and other food ingredients are combustible—sometimes, highly so. The Imperial Sugar factory explosion in 2008 in Savannah, Ga., is still a cautionary tale for the industry; it resulted in 14 deaths, 36 injuries, and widespread facility destruction. Food and agriculture were responsible for nearly 50% of industrial fires and explosions between 2018 and 2021, according to the “Combustible Dust Incident Report 2021,” available at dustsafetyscience.com.
A dust collection system is used to prevent the buildup of dangerous dust in the facility as a whole and inside enclosed areas such as silos, conveyor systems, batch mixers, and other production equipment. But the dust collector and ductwork also provide many of the ideal conditions for a dust-based fire or explosion:
- The dust collector generates a lot of airflow, guaranteeing a ready supply of oxygen for a combustion reaction;
- The dust and filter media supply fuel;
- Dust inside the system is dispersed in a cloud during collection; and
- The dust cloud is contained in an enclosed area (ductwork or the dust collector filter chamber) where pressure can build up.
Under these conditions, only one more element is needed to start a combustion reaction: an ignition source, which may come from a spark from machinery or processes, an open flame or heat source, friction, or even static electricity. (Some highly combustible dusts can even self-ignite under the right conditions.) A dust collector fire may start when a spark hits a flammable filter media that is loaded with dust. If a combustion reaction starts within an airborne dust cloud inside the dust collection system, the result will be an explosion. The fire triangle and explosion pentagon show the difference (see figures 1 and 2).
Once a fire or explosion starts in the dust collection system, it can rapidly spread to other parts of the facility, leading to widespread damage or a dangerous secondary dust explosion. For these reasons, dust collector fire and explosion safety are essential.
Five Essential Dust Collector Safety Elements
Fortunately, most dust collector fires and explosions are preventable. By removing any of the legs of the fire triangle or explosion pentagon, it is possible to prevent a combustion reaction from starting or stop one in its tracks. There are several critical elements to dust collector fire and explosion safety: