Dust Hazard Analysis
Your Key to NFPA Compliance
A combustible dust explosion and fire destroyed the West Pharmaceutical Services plant in Kinston, North Carolina. causing six deaths, dozens of injuries, and hundreds of job losses. The culprit was a fine plastic powder that had accumulated above the suspended ceiling in the manufacturing area.
Three iron dust flash fires occurred in less than 6 months at Hoeganaes Corporation in Gallatin, TN. 5 people were killed and 3 injured. The CSB found dust on beams and ledges, iron dust leaking from equipment and unreliable dust collectors.
The Imperial Sugar Company in Savannah, GA was completely destroyed by a series of sugar dust explosions that killed fourteen workers and injured another 38. They were fined almost $8.8 million. As you can see, dust is more than a maintenance issue. It is a matter of life and death. In the twenty five year period between 1980 and 2005, the US Chemical Safety and Hazard Investigation Board (CSB) recorded 281 combustible dust incidents that killed 119 works and injured 718 others. Combustible dust, present in almost every manufacturing and processing facility, is both common and deadly. However, with proper controls and diligent maintenance, combustible dust fires and explosions are 100% preventable. Recognizing that combustible dust hazards are complex and little understood, NFPA 652 was introduced to address those issues.
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NFPA 652-2019 Updated Compliance Requirements
The clock is ticking. The 2019 edition of NFPA 652,  Standard on the Fundamentals of Combustible Dust, revises the deadline for facility operators to complete a Dust Hazard Analysis (DHA). The new Sept 7, 2020 DHA deadline isn't limited to new facilities. It is retroactive to all existing facilities that handle combustible dust. Another significant change - NFPA 652 mandates a DHA review every five years to address changes that may have occurred to a facility's process, equipment, product or practices.
What Is Combustible Dust?
By definition, combustible dust is "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."
We commonly think of materials like coal, wood, rubber, paper and pesticides as combustible. What we often overlook is that many materials that we may not consider flammable, metals like aluminum or iron, can also be explosible in dust form. Under certain conditions, even a small amount of dust can combust.
Examples of potentially combustible dusts include: -
Agricultural Products (egg whites, powdered milk, cornstarch, sugar, flour, rice, grain)
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Agricultural Dusts (apple, carrot, cocoa powder potato, gluten, cotton)
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Carbon Dusts (charcoal, cork, cellulose)
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Chemical Dusts (sulpher, calcium acetate, dextrin, lead stearate)
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Metal Dusts (bronze, potassium, calcium, magnesium, titanium, zinc)
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Plastic Dusts (resins like epoxy, melamine, phenol)
Facilities can choose one of two methods to determine combustibility.
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Industry Published Values: Values based on public data (NFPA Documents, Safety Data Sheets, etc) is acceptable if the published data is representative of your material. 
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Dust Testing: The most reliable method when a representative example of your material is used. Inaddition to determining combustibility, laboratory testing can also provide properties specific to your dust, such as Kst, Pmax, MEC, MIE, etc.
Dust Hazard Analysis (DHA)
A Dust Hazard Analysis (DHA) is not just another box to check. DHA is an invaluable tool used to identify, evaluate and combat potential fire and explosion hazards associated with combustible dusts. Done properly, a DHA not only identifies areas of concern but provides specific steps to mitigate the hazards, protecting both lives and property.
HOW? 1. IDENTIFY AND PRIORITIZE Identify fire, flash-fire, deflagration and explosion hazards. Prioritize those presenting the greatest risk to those that can be addressed at a later date. 2. EVALUATE Identify safeguards currently in place and evaluate their effectiveness. Were they properly implemented? Do they comply with NFPA standards? 3. RECOMMEND Recommend additional actions and procedures to safeguard your personnel and facility. 4. DOCUMENT NFPA 652 requires DHA documentation showing that you are compliant with current codes and standards, or that you have at least identified problem areas and have a plan to address them. Don't skip this step! Under certain circumstances, you may be required to produce your documentation. PacMoore Products, a food ingredient manufacturer in Indiana, was fined over $19,000 for several safety violations. One citation was for failing to conduct a DHA on facility equipment, including the dust collection, storage, and Class II, Combustible Dust transport systems. Equally important, the DHA documentation serves as an invaluable reference for management.
Who Performs a DHA?
NFPA 652-2019 states that a DHA must be performed or led by a "qualified person". If you are a plant manager, a facility operator, a plant engineer or a maintenance operator, you may believe you are that qualified person. There are plenty of books and articles to guide you. But, before assuming that role, understand what is involved.
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Analyze each step of the manufacturing process, identifying those that may create a hazard. For instance, what may not have been combustible in one step may become combustible in the next, due to changes in material composition or the introduction of a new element. Ignition sources absent in one step may be present in another.
This may be one time that hiring safety professionals who specialize in Dust Hazard Analysis is the prudent way to go. Remember, a DHA is very time intensive and there is no room for mistakes. A faulty DHA may give you a false sense of security.
Whatever approach you take, understand that simply completing a DHA does not improve plant safety. You must act on the results of the analysis.
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STAY TUNED!
FREE WEBINAR
COMING THIS FALL
Get your questions answered, keep your facility safe and comply with NFPA and OSHA. TEC Engineering will host a free webinar on Dust Hazard Analysis. Featured speaker will be Tim Heneks with Dustcon Solutions.
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I spent the summer by a lake watching a patch of lily pads. Every day, the patch doubled in size. It took 48 days for the patch to cover the entire lake. How long did it take for the patch to cover half the lake?
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QUOTE OF THE DAY
"You are never to old to set another goal or to dream another dream"
-- C.S. Lewis
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