If your dust is combustible, you need to be concerned with the risk. According to a report published by Dust Safety Science¹, 34 dust explosions and 115 fires were logged globally in just the first six months of 2019. The incidents during this period resulted in 13 deaths and 66 injuries.
Could any of these dust explosions or fires have been prevented had a dust hazard analysis (DHA) been conducted? Proper dust explosion protection and housekeeping are critical, but new safeguards need to be taken. According to NFPA 652, you should have a DHA complete by now for any dust or powder that is collected. According to Dust Safety Science, in the past four years, the US averaged 33 dust explosions, 30 injuries, and three fatalities per year. These fires and explosions resulted in over $1 million in property loss.
Dust collectors are being scrutinized because 53% of all primary dust explosions happen within dust collectors, which can result in secondary explosions in or around the facility. Explosions are devastating as are all safety incidents when they can be avoided. Know your options.
Location of primary explosion by operation¹
Consider the key points listed below and ask yourself "Do I need explosion protection?"
The recommended approach for explosion and fire prevention can be implemented with a dust hazard analysis (DHA).³ What is a DHA? It’s a systematic review of all processes. The review determines where a fire or explosion could occur. It looks at the causes and what the consequences are and determines if existing safeguards are enough. If they aren’t, the DHA will include a recommendation of what safeguards are required.
You need to make sure that the review is completed by a “qualified person.” Someone with the experience and credentials that can properly identify potential abnormal conditions. You can expect that they will look at all processes that create dusts.
The analysis will include how fires could move between processes, determine what is normal, abnormal, and what an upset condition would look like. They will itemize all processes and equipment including bins, tanks, silos, hammer mills, pulverizers, grinders, welders, dust collectors (wet and dry) conveyors, screw augers, bucket elevators, sifters, and screens, etc.
The DHA will identify all materials that create dust and what the hazard could be, review all SDS sheets, and review books and online material for information on the dust. The analyst will determine if dust requires testing by a lab and help you develop a plan for dust control, housekeeping, training, and preventive maintenance.
If just one part of the fire triangle or the explosion pentagon can be removed, the hazard is eliminated. Both figures have oxygen, ignition source, and fuel. Oxygen is pretty much impossible to eliminate, so we will concentrate on the other two, ignition source, and fuel.
All decisions of what is required come down to the “authority having jurisdiction” (AHJ). This person could be the local fire marshal, OSHA inspector, or the insurance underwriter to name a few. There should be someone at your facility that works with the AHJ on preventative measures and the protection plan designed for your facility. The bottom line is that the owner of the facility is responsible for all local, state, and federal codes, standards, laws, and regulations for combustible dusts.
If you haven’t completed your DHA as required by NFPA 652 and you need help finding an analyst, contact a specialist for assistance by email at dusthog@parker.com or visit www.parker.com/airquality.
This blog was contributed by Phil Rankey, lead application engineer, Parker Industrial Gas Filtration and Generation Division.
Sources
1 dustsafetyscience.com/dust-safety-science-podcast/, August 24, 2020
2 dustafetyscience.com, August 24, 2020
3 www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=652, August 2020
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