How is dust explosive? You may know dust is explosive, but how is that really possible? When you try to start a camp fire, do you try to light the end of a large log? Of course not! You gather up starter materials like brush and sticks or peel off some splinters to make a kindling. The same principle applies to dust explosions. Materials that you might not think of as combustible are much more likely to be explosive when they are broken down into very small particles (dust).Where is Combustible Dust found and who is at risk of a Combustible Dust Explosion?
Industries involved in handling, conveying, dividing, crushing, drying, compacting, grinding, pulverizing, sanding and/or sawing of materials are at highest risk; whether they are producing particles for use in products or they are simply a by-product of the manufacturing process.
A study by FM Global in 2008 determined that more than half of all explosions occurred in plants with dust collectors, followed by impact equipment and then silos and bins. Read more Facts About Combustible Dust.
Is my dust explosive?
Most all natural and synthetic materials, as well as some metals, can form a combustible dust hazard when they are present in very small particles. OSHA's Combustible Dust Poster is a good place to start for referencing materials that have the potential to cause a dust explosion.
If your dust is is listed on the Combustible Dust Poster it has the potential to cause a dust explosion and you should consider Combustible Dust Testing. Dust testing will give you a base line value (kst) of the explosibility of your dust. If the test yields a result that indicates you have a dust with a high kst, further analysis will be required. Not that this does not necessarily mean you have the proper environment or conditions that would put you at risk of a dust explosion.
How do I protect my plant and people from Dust Explosions?
If you’ve determined that your dust is explosive, how do you protect your plant, people and equipment from explosions? There are two methods of protection - Mitigation and Prevention.
Mitigation is a damage limiting method. An explosion may occur but engineered measures are employed to eliminate the potential for injury and reduce damage. Mitigation techniques include venting, inerting, containment and dilution.
Prevention eliminates the potential for an explosion all together. Prevention techniques include Isolation, both chemical and mechanical, and Suppression.
Which method should I use?
This will be determined by your dust, facility and hazard. The first step I finding out which protection is best suited for your hazard is scheduling a Hazard Analysis. Combustible Dust Consultation and DHAs Along with dust testing results, a thorough review of your facility and your process equipment will determine which protection method to utilize based on your facility, the hazard, current NFPA code and your project budget and goals. In general, the following factors determine the type of protection to use.
1. Kst (explosibility of your dust)
2. The type of vessel/equipment (size and shape)
3. Pressure (normal operating, maximum)
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