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Combustible Dust Standard: NFPA 652


Combustible dust is any fine material that can catch fire and explode when mixed with air. OSHA defines combustible dust as “…a solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition, which presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations.”

This does not always mean the types of material normally considered either combustible or dangerous. It can include metal dust, wood dust, plastic or rubber dust, coal dust, biosolids, dust from certain textiles—even organic dust, like flour, sugar, paper, soap and dried blood.

Why Standard is Important

If a company has processes that create dust or use powders, then it has a responsibility to determine if a combustible dust hazard exists. NFPA 652: Standard on the Fundamentals of Combustible Dust, 2016 edition, became effective Sept. 2015. This standard was created to promote and define hazard analysis, awareness, management and mitigation. The standard also issues a new term, “Dust Hazard Analysis,” or DHA, to differentiate this analysis from the more complex forms of process hazard analysis methods currently found in industry. NFPA 652 is the starting point for this analysis. It will guide you step by step in identifying hazards and what to do next.

The NFPA standards have required a process hazard analysis since 2005. NFPA 652 takes this requirement further by making this requirement retroactive to existing installations, with a deadline. A DHA is now required for new installations and upgrades to existing installations. The standard allows three years to complete this DHA. To illustrate the importance of this hazard analysis, many OSHA citations regarding combustible dust hazards list the lack of a hazard analysis at the top of the citation.

Combustible dusts are created during the transportation, handling, processing, polishing and grinding of the materials. Abrasive blasting, crushing, cutting and screening dry materials can also create dust.

The types of workplaces most at risk of combustible dust include:

  • Food production
  • Woodworking facilities
  • Metal processing
  • Recycling facilities
  • Chemical manufacturing (rubber, plastics, pharmaceuticals)
  • Grain elevators
  • Coal-fired power plants

Any workplace that generates dust might be at risk, however. This is why it’s essential to conduct a thorough risk assessment.

Key Compliance Requirements:

The purpose of a dust-collection system is to remove and isolate dust away from people who can inhale it and process areas where it could accumulate and become a deflagration hazard. The DHA will identify the following conditions that may exist external or internal to the system that contribute to a fire or deflagration hazard:

  • Presence of oxygen: Air is the oxidant
  • Presence of fuel: Combustible dust where ever it is found, including floors, elevated surfaces, inside ducts, and inside process enclosures and machines
  • Dispersion of fuel: includes pulse cleaning inside dust collector; use of compressed air for cleaning; and events that can dislodge dust from elevated surfaces
  • Ignition sources: Sparks, electrical shorts, hot work, electrostatic discharge, flames, rotating equipment, hot surfaces
  • Containment locations: inside pipes; inside dust collectors; and inside any process enclosure or machine

Compliance Assistance:

Because so many different types of workplaces might contain potential combustible dust risks, it’s essential to conduct a thorough risk assessment. Failing to comply with this standard can leave you open to serious fines and even more serious injuries, if an incident occurs.

• OSHA offers a lengthy list of materials that could produce combustible dust:

• Become familiar with NFPA 652: Standard on the Fundamentals of Combustible Dust. It provides basic principles and requirements for identifying and managing fire and explosion hazards from combustible dust.

• OSHA looks to this standard for guidance when it comes to best practices for preventing combustible dust fires and explosions. Those who don’t take the necessary steps to protect workers can be fined for violations under 18 different standards as part of OSHA’s Combustible Dust National Emphasis Program.  This includes the General Duty Clause and 29 CFR 1910.22, the main housekeeping standard.

• For more an in-depth discussion of combustible dust, see the article titled “How to Prevent Combustible Dust Incidents in the Workplace” in WMHS’s November 2018 issue:

Sponsored By:
What does NFPA 652 mean to Nilfisk? Proper housekeeping is a powerful and essential line of defense against many types of workplace hazards, and combustible dust is no exception. NFPA 652 recommends cleaning methods such as vacuuming but also outlines specific design requirements to ensure the equipment can meet the demands of collecting combustible dust. In the absence of a formal OSHA rule, NFPA 652 is vital to guiding our manufacturing customers on how to identify, measure and, most importantly, choose the proper industrial vacuum to safely mitigate their combustible dust risk.

Nilfisk, Inc., Industrial Vacuum Division, 800-645-3475,

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