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Combustible Dust Explosions
Understand and Prevent
Is your industry safe from a dust explosion? Did you know that even a typically non-hazardous material like sugar or plastic can catch fire and explode? J
ust about everything, including food, dyes, chemicals, and metals - even materials that aren't fire risks in larger pieces - has the potential to be combustible in dust form.
Combustible dust (fine particles that present an explosion hazard when suspended in air under certain conditions) is present in nearly all industries - as a raw material, a final product or unwanted waste. Even small accumulations of dust - as little as 1/32 of an inch - can create a dust explosion hazard if spread over a sufficient surface area.
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| Dust Explosion at Imperial Sugar |
A 2016 NFPA (National Fire Protection Association) report estimates an average of 37,000 fires at industrial or manufacturing properties each year, with annual losses from these fires estimated at 18 civilian deaths, 279 civilian injures, and $1 billion in direct property damage.
What Is A Dust Explosion?
Dust explosions occur when a fine, combustible dust is suspended in air and ignited. The rapid burning and release of gaseous products results in a pressure rise and explosion.
Dust explosions can be categorized as either primary or secondary.
- Primary explosions take place in a confined area, such as a cyclone, storage silo, or enclosed part of the manufacturing plant. After detonation, the shock wave can damage and often rupture walls. Burning dust and gases from the explosion are expelled into the surrounding area.
- Secondary explosions result when the primary explosion disturbs settled dust and it becomes airborne. This new dust cloud can itself ignite, causing a secondary explosion often many times the size and severity of the primary explosion. If enough dust has accumulated, these secondary explosions have the potential to bring down entire facilities, causing immense damage and fatalities.
The "Dust Explosion Pentagon"
All five key elements shown in the "dust explosion pentagon" are needed for a combustible dust explosion to occur.
1) Explosive Dust: The dust must be combustible and fine enough to become airborne.
2) Suspended Cloud: The dust cloud must be of explosive
concentration.
3) Confined Area: An enclosed structure surrounding the suspended dust cloud must exist to achieve the characteristic pressure rise.
4) Oxygen: There must be sufficient oxygen in the atmosphere to support and sustain combustion.
5) Ignition Source: There must be an ignition source.
The ignition sources of of industrial dust explosions shown below may surprise you.
Prevention
Fortunately, combustible dust incidents are entirely preventable. However, explosion prevention and mitigation, along with injury/damage control methods and complying with the latest codes and standards can be overwhelming.
TEC Engineers can help make this process easier. We work closely with CVT Technology, specialists in complete explosion protection solutions for the prevention and mitigation of explosion hazards that result from process powders and dry bulk materials. Products and services offered include:
- Combustible Dust Audits
- Combustible Dust Testing
- Equipment Training
- Various explosion mitigation products, including explosion vents, isolation valves, flameless vents, and chemical suppression equipment
Call us today to schedule your walk-through.
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