The scary thing about dust is that it doesn’t just burn it explodes.
Dust it’s a hazard in many workplaces that you might be aware of, you know it can cause surfaces to become slippery and that you don’t want to breathe it in or get it in your eyes, but what if I told you a layer of dust is thin as a few sheets of paper could be responsible for a massive explosion?
Many types of dust can explode and these include not just organic materials like flour, sugar or wood but also inorganic materials such as some metals, paints, plastics, pharmaceuticals, and even some types of textiles.
What Types Of Dust Can Explode?
OSHA has identified more than 130 products or materials that pose a hazard for dust explosions. The fact is many facilities that have processes that produce dust or fine particles may be at risk of a dust explosion, often with catastrophic results unless precautions are taken and proper procedures are followed.
There are many materials that can become combustible under the right conditions, but almost all buildings are susceptible. You can refer to this poster created by the US OSHA organization: https://www.osha.gov/Publications/combustibledustposter.pdf
How Does Combustible Dust Explode?
The National Fire Prevention Association defines combustible dust as “a finely divided combustible particulate solid that presents a flash fire hazard or explosion hazard when suspended in air or the process specific oxidizing medium over a range of concentrations.”
You’re probably familiar with the ingredients necessary to start a fire, they make up what’s commonly referred to as the fire triangle, they are fuel, oxygen, and heat. When talking about combustible dust add two more ingredients, dispersion and confinement. This is what is referred to as the dust explosion Pentagon.
In order for a dust explosion to occur all five of these ingredients must be in place. Dust explosions happen when dust fuel is dispersed into oxygen, reaching a sufficient level of concentration in an area of confinement and comes into contact with an ignition source, heat.
Primary And Secondary Dust Explosions
It’s not bad enough that a dust explosion occurs in the first place but many times it leads to a secondary explosion when the initial explosion sends other surface dust airborne into a second explosive cloud.
What Is Deflagration?
Another term to that is used to describe dust explosions is deflagration. In a deflagration, the burning substance releases heat, gases, particles, and sparks that ignite and spread fire. During a dust explosion, this process is so rapid that heated and gases create an extreme air pressure that can damage or destroy structures.
How Do You ID A Combustible Dust Hazard?
Well, the best practice is to keep the workplace as clean and dust free as possible but many experts will say that if you are able to write in the dust, or it is a thick as a paper clip or dime you have a potentially hazardous situation. In reality there are many factors, such as particle size, if the dust is of combustible type, air currents, ignition sources, confinement of the dust cloud and many more.
A couple questions that you can ask are:
- Do you manufacture or use materials that can become dust?
- Do you use processes such as cutting, grinding, polishing, cleaning or blasting that can create dust?
- Have you researched to see if the dust you create is combustible?
- Have there been other documented cases of similar situations that resulted in dust explosions?
- Do you have potential ignition sources?
- Can dust enter or accumulate on electrical enclosures or equipment?
- Are measures taken to make sure smoking or other ignition sources are away from production areas?
- Do you have areas overhead where dust can accumulate?
- Have you looked for areas that are hidden for accumulated dust such as ventilation, conveyor equipment, in duct work, on support beams, etc.?
- Do you have a housekeeping program to regularly remove dust?
- Do you have a dust collection system?
- Is your staff aware of combustible dust and it’s hazard?
- Have employees been trained on safe cleaning methods?
Watch this Video of a dust explosion at Abbotsford furniture manufacturer where firefighters narrowly escaped injury.
What Are Some Prevention Measures?
Now that you have identified the potential hazards of dust explosions, you need to take action on preventative measures.
- Use only approved vacuums and wiping measures when cleaning, use of compressed air and brooms can make the situation worse if not correctly used.
- Eliminate “hidden areas” where dust can accumulate unnoticed
- Use only a dust collection system that is designed to eliminate or control combustible dust. Most fan systems will only stir the air, adding dust particles into the air, worsening the situation.
- Create a housekeeping policy that ensures the dust buildup is under control.
- Regularly inspect machines, ducts, and ventilation systems for dust. Repair or clean promptly.
- Educate all employees about combustible dust, the hazards, and how they can help eliminate the potential for fire or explosion.