Controlling Combustible Dust in Your Plant

FromPowder/Bulk Solids

Four Steps to Control Combustible Dust in Your Plant

Hi-Vac manifold piping system to help clean up chips and cuttings from machine centers
Hi-Vac manifold piping system to help clean up chips and cuttings from machine centers

According to the Spring 2015 Office of Information and Regulatory Affairs report, combustible dust explosions have been an OSHA focus for years. The U.S. Chemical Safety Board reported in late 2006 that 199 workers had died in 2005 alone as a result of combustible dust events. OSHA has increasingly focused on how to prevent explosions caused by combustible dust. Together with the U.S. Department of Labor, OSHA published a bulletin in November 2014 titled, “Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions.”

According to the bulletin, there are three components of a dust explosion, and those are dust, an ignition source (usually heat), and oxygen in the air that helps the fire spread rapidly. Together with
hazard assessment, OSHA suggests in the bulletin that tactics like improving ventilation design would help prevent combustible dust explosions and fires.
The fact is that fire and explosions caused by combustible dust can be prevented in many cases. Four steps can help a plan become more OSHA-compliant and safer for the workers there.

Step One: Install a Plant-Wide Manifold Piping System

Together with a high-quality stationary industrial vacuum system, a pneumatic conveying system or a central vacuum cleaning system can effectively reduce the amount of combustible dust in a plant. Shorter hoses at each workstation can be used so that employees do not have to touch potentially hazardous material and so that they can clean their areas without the fatigue that larger systems can cause.

Step Two: Use a System That Allows Controls to Be Positioned outside the Classified Area

The installation of a manifold piping system, together with the use of a powerful industrial vacuum system, can enable installation of the control panel to occur outside of the classified area. This means the plant can continue to use NEMA 4 classification control panel versus the far more expensive NEMA 7/9 controls. If one of the impediments to plant safety is perceived cost, it is important to note that this simple change can potentially save thousands of dollars.

Step Three: Add a Back Draft Isolation Valve or Pressurized Chemical Isolation outside the Plant

The installation of a back draft isolation valve or a pressurized chemical isolation outside the plan will help to ensure that any ignition source outside of the vacuum system will not enter the plant.

Step Four: Pick the Best Possible Industrial Vacuum System

Perhaps the most important step to help prevent combustible dust fires and explosions is to invest in the best possible industrial vacuum system. These systems need to be durable, reliable, and provide several different safety features that are central to meeting combustible dust control objectives. Among the safety features to look for are:

    • No flame escape

    • No air inrush thanks to quick reclosing

    • Air-tight enclosure

    • Operable in all mounting positions


Look for a vacuum system that is virtually maintenance-free. A stainless steel material inlet  assembly, grounding the filter bags or cartridges, utilizing a grounded, smooth bore rubber hose and aluminum or stainless nozzles, all can help to eliminate sparking potential. The investment in such a system compared to the costs in damage, not to mention in human lives, is easy to justify.

Controlling combustible dust is a constant concern for plants of all kinds. There is a perpetual risk of danger, but with a strong plant design, clear safety procedures, and an investment in a high-quality
industrial vacuum system, tragedies can easily be avoided.

    Shawn Doolittle is sales manager industrial products, Hi-Vac Corp., Marietta, OH. For more information, call 800-752-2400 or visit

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