Combustible Dust, It's Just Not Worth the Risk
Combustible Dust Hazards | Tips for on-the-Job Safety
Industrial work in any field has its challenges. The best way to face these difficulties is to learn about preventative measures before the risks become a reality.
Air Dynamics Industrial Systems Corporation has over two and half decades of experience with problem-solving in a wide range of hazardous industrial environments. Below are some helpful tips we have learned through the years, as well as links to important articles on workplace safety. Please use this resource to help protect yourself, your coworkers, and your employees.
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Identifying Combustible Dust Factors
Many kinds of dust are capable of combustion (exploding). OSHA and the Department of Labor (DOL) have identified five factors that are present during a dust explosion/deflagration:
Combustible Dust
Containment of Dust
Dispersion of Dust Cloud
Oxidation
Ignition/Source
Through the combined effects of these factors, a dust deflagration will occur.
Combustible Dust | Pentagram
The depth of the dust is a major factor in the explosive nature of combustible dust. OSHA has identified that as little as one thirty-second of an inch (1/32”) of dust is all it takes for some dust to form a dust cloud and deflagrate.
This is the depth of a paper clip.
Dusts range in explosive capability categorized by a Kst Value. The Kst value is a numerical indicator to demonstrate the severity of a dust explosion. The value ranges from 0 (no explosion) to over 400 (an extremely dangerous explosion). Dusts are captured and tested in specific labs to determine the Kst Value.
(EXPLOSIVE INDEX)
Types of Combustible Dust
Each industry identified below has regular interaction with the combustible material. For each dust, if the proper precautions are not taken, a serious dust explosion will occur.
Below are assorted samples of combustible dust categories. More may exist and are not listed as this is not an extensive overview. For full disclosure of this information follow this link to go to OSHA's website and see their detailed guidelines on the various explosive dust.
Agricultural Explosive Dust
The AG Industry faces many combustible dust dangers due to the usually volatile nature of organic dust. For example, corn dust (75 Kst) is a “small” explosion. However, cornstarch ranks in at 202 Kst! Almost triple the explosive capacity from a very similar dust.
Keep in mind that even low-scale Kst values can cause significant destruction. The Imperial Sugar Plant outside of Port Wentworth, Georgia in 2008 was caused by sugar dust with a Kst value of around 138.
Though these are only a few examples, the agricultural industry faces numerous types of explosive dusts ranging from egg white powder to hops used in brewing beer and tobacco dust. See the attached link in the references section to view a full list provided by OSHA.
Click the photo or the button below to read about the Imperial Sugar Explosion.
Lumber Industry
Logging or woodworking produces many kinds of dangerous dust. As with the AG Industry, the dust is organic. Since it is organic we know it has combustible potential. In a likewise fashion, the power of the explosion depends on the material being handled. Wood dust is normally a highly combustible material, and the Kst values demonstrate this fact. Wood flour ranks in at 205 Kst, similar to Cork dust at 202 Kst, demonstrating the capacity for a powerful explosion.
In 2015, a wood flour explosion in Bosley, England killed four workers and destroyed the mill in which they worked. Wood flour averages 205 on the Kst scale. This “moderate” explosion leveled a mill with ease.
Click the picture to read an article from the BBC on the explosion. Photo credit Sky News.
Manufacturing Metal Dust
Manufacturing metals can cause some dangerous dust to disperse in your facility. While dust such as Bronze (31 Kst) has a relatively low explosive capacity, metal dust can be extremely dangerous.
Remember: even dust with a low Kst value can explode with terrible results. Anything over 0 on the Kst scale is volatile. Dust such as magnesium has a 508 Kst value! The explosion that could be caused by this dust would be devastating.
A deflagration occurred at AL Solutions in 2010 that resulted in the deaths of three employees and severely injured a fourth. Zirconium and titanium dust, both of which are highly combustible, were located throughout the facility. Poor housekeeping procedures produced the fatal combination of a dust explosion. AL Solutions had three (3) other incidents, two of which resulted in deaths, that were caused by poor design and housekeeping. The case of AL Solutions is a prime example of a preventable combustible dust tragedy.
Click the photo to read the NFPA Case Study on AL Solutions Explosion. Photo Credit: US Chemical Safety Board
Manufacturing Plastics
Plastics are an extremely combustible material. This is due in part to the chemical nature of the plastics. Fine plastic dust such as polyethylene, more commonly known as PET, has a 134 Kst value. A very "moderate" explosion that could level a building.
An example of this would be the West Pharmaceutical Services explosion in 2003. Polyethylene (PET) plastic dust built up around the plant due to poor housecleaning procedures. After the five explosive conditions were met, the dust deflagrated and claimed the lives of six (6) employees and injured another thirty-eight (38).
Click the photo or the button to read more about the West Pharmaceutical Services Explosion.
Manufacturing Carbonaceous Material
Materials such as charcoal from wood, coal (bituminous), soot, and other carbon-based dust maintain a high chance of combustibility. These types of explosions are extremely deadly due to the confined nature of mining. This requires companies in this field to take extra precautions when dealing with coal dust. Using water to dampen the dust is a common method, as well as other house-cleaning standards.
"Between 1986 and 2010, there were 10 multiple fatality mining explosions in underground coal mines in the U.S" - CDC on Mining Explosions
Click the photo or follow the button to read more on Mining Dust Explosions.
House-keeping Procedures for Combustible Dust
OSHA has identified several critical steps to preventing combustible dust deflagration.
The first and most important step is identifying and understanding the explosive potential of the dust you have at your facility.
The second step should be a careful overview of current housekeeping procedures. OSHA and the NFPA have explicitly demonstrated proper implementation. Have you located areas where dust is accumulating in your shop or facility? Is this dust being cleaned with a non-static vacuum system or, in permissible areas, being swept and discarded safely?
If you have questions about your specific application, don’t hesitate to call our dust control specialists. We have over two and half decades of dealing with all forms of combustible material. We design solutions that are meant to solve your challenge, not just a temporary fix.
Whether you’re seeking a new solution or a retrofit of an outdated system, Air Dynamics Industrial Systems Corporation can help you protect your employees, investments, and very possibly your life.
Below are links to OSHA's and NFPA resources. It is important to familiarize yourself with the information they provide as it could save your plant, your coworkers, or your life.
General Combustible Dust Information:
Feed and Grain Information:
If you take nothing else from this page, remember that dust explosions occur every year, in the United States and around the world. If you do not prepare preventative measures, you are at risk, as are your company, facility, and coworkers. This is not meant as a scare tactic, just simple truth.