Industrial Hygiene
Photo: tiero / iStock / Getty Images Plus
Dust
Can Be Catastrophic
Combustible
Good housekeeping and right cleaning equipment are critical in manufacturing
By Nora Ashmen
C
ombustible dust explosions continue to cause catastrophic incidents across industries worldwide. Despite increased awareness and regulations, primary and secondary explosions due to accumulated dust are still occurring, often resulting in devastating loss of life, facility damage, and operational downtime. One of the most effective preventative measures is maintaining a clean facility through proper housekeeping and the use of intrinsically safe, explosion-proof, compressed-air operated industrial vacuum cleaning systems specifically engineered for hazardous dust environments.
The Global Threat of Combustible Dust Explosions
Catastrophic combustible dust explosions are not a thing of the past. As recently as 2024, incidents have occurred in food processing, metalworking, woodworking, and chemical manufacturing facilities. In most of these cases, an initial (primary) explosion disturbs accumulated dust, leading to a more powerful (secondary) explosion that causes the most destruction.
According to data from the U.S. Chemical Safety Board (CSB), hundreds of dust-related fires and explosions are reported every year in the United States alone. Internationally, similar trends persist despite ongoing education and standards. What is the common denominator? Inadequate housekeeping practices and the misuse of cleaning equipment in potentially explosive environments.
What Is Combustible Dust?
Combustible dust is any fine particulate that has the potential to catch fire and explode when suspended in air under the right conditions. Materials ranging from food ingredients to plastics, wood, pharmaceuticals, and metals can generate combustible dust.
The Five Elements of a Combustible Dust Explosion (The "Dust Pentagon"):
1. Fuel: Combustible dust itself
2. Oxidizer: Typically, ambient air (oxygen)
3. Ignition Source: Sparks, hot surfaces, static discharge, etc.
4. Dispersion: Dust must be suspended in the air
5. Confinement: Enclosed space (walls, ceilings, ducts) where pressure can build
Removing any one of these five elements eliminates the explosion hazard. While ignition sources are often controlled through electrical classification and engineering controls, housekeeping addresses both the “fuel” and “dispersion” components by preventing the accumulation of dust and its resuspension into the air.
Even with engineered safety controls and explosion mitigation systems in place, dust accumulation remains a leading contributor to explosion severity.
The Dangers of Using Standard Shop-Type Electric Vacuums
One of the most dangerous mistakes in combustible dust environments is using traditional shop vacuums or general-purpose electric vacuums for cleanup. These devices are not designed for explosive dust atmospheres and introduce several hazards:
Non-Intrinsically Safe Components
Standard vacuums often contain motors, brushes, and switches that can produce sparks or excessive heat—common ignition sources for a dust explosion.
Lack of Grounding and Bonding
Electric vacuums typically lack proper grounding, allowing static electricity to build up. A single static discharge in a dusty environment can ignite a suspended dust cloud.
No Explosion Containment or Isolation
In the event of ignition, these vacuums can become sources of secondary explosion propagation, endangering personnel and equipment.
Inadequate Filtration
Many shop vacuums do not contain HEPA or ULPA filtration, allowing fine particulates to pass through and become airborne again, reintroducing dispersion risk.
Why Use Intrinsically Safe, Explosion-Proof, Compressed Air Operated Industrial Vacuums?
To safely clean combustible dust, facilities must use certified explosion-proof vacuum cleaning systems specifically designed for Class II, Division 1 and 2 hazardous locations (or ATEX-certified for European applications). Compressed air operated vacuum cleaners provide a range of safety benefits:
Key Features and Benefits:
• No Electricity, No Sparks: Powered by compressed air, these units eliminate the risk of internal electrical ignition sources altogether. No brushes, no motors, just safe, spark-free operation.
• Fully Grounded and Bonded: Explosion-proof vacuums are designed to dissipate static electricity safely through conductive hoses, bonded components, and grounded systems.
• HEPA Filtration: High-efficiency filters trap even the finest particles, preventing the re-aerosolization of dust and reducing inhalation and dispersion risks.
• Explosion-Proof Construction: Certified units are built using non-sparking materials (like stainless steel or carbon steel) and sealed designs that can contain internal pressure events.
• Compliance with OSHA & NFPA Standards: Use of certified equipment ensures compliance with OSHA 29 CFR 1910.22(a)(1), which requires all places of employment to be kept clean and orderly, and NFPA 652, which mandates housekeeping as part of dust hazard analysis.
Housekeeping is a First Line of Defense
Even with engineered safety controls and explosion mitigation systems in place, dust accumulation remains a leading contributor to explosion severity. Routine, scheduled housekeeping with appropriate vacuum systems not only protects people and assets but also extends equipment life and improves overall air quality in the facility.
Best Practices:
• Identify and eliminate hidden dust accumulation zones (rafters, beams, behind equipment).
• Develop a documented cleaning protocol tailored to the material being processed.
• Use only certified explosion-proof vacuum systems appropriate for your dust hazard classification.
• Train personnel on safe vacuum operation and maintenance procedures.
Conclusion
The use of improper cleaning equipment, such as electric shop-type vacuum cleaners in combustible dust environments, is a preventable risk that still causes fires and explosions today. Investing in intrinsically safe, explosion-proof, compressed air operated industrial vacuum cleaners is not just a compliance measure; it's a critical safety solution. When paired with disciplined housekeeping practices, these industrial vacuum cleaners serve as a frontline defense against deadly and destructive dust-related incidents.
Clean manufacturing plants aren’t just efficient, they are safe.
Nora Ashmen is Director of Marketing at VAC-U-MAX.
September 2025
VOL. 59 NO. 7