Are You at Risk for a Combustible Dust Explosion? | Nilfisk Official Website
May 01, 2009

Are You at Risk for a Combustible Dust Explosion?

After decades of work-place explosions leading to hundreds of injuries and fatalities, combustible dust is finally a national headline that OSHA cannot ignore. While there are still no laws regarding combustible dust procedures, the agency has made quite a bit of headway in outlining recommendations for prevention and conducting random audits of "at-risk" facilities. By now, if you are a plant manager that handles dry bulk solids, you should be bulking up your maintenance plan which may include an industrial vacuum purchase--but did you know that using the wrong vacuum can actually add to the risk of a combustible dust explosion?

Many vacuum companies offer basic models dressed up with a few anti-static accessories and describe them as suitable for explosive material. With metal parts and non-enclosed motors, these vacs can create arcs, sparks or heat that can cause ignition of the exterior atmosphere and overheating that can ignite dust blanketing the vacuum. Plant Managers should take no chances when it comes to protecting your facility and look for CERTIFIED explosion-proof vacuums that are explosion-proof to the core. This means that everything from the outer shell to the internal mechanics including the motor, switches, filters and inner chambers should be grounded and constructed of non-sparking materials such as stainless steel.

Approval by a nationally recognized testing agency such as CSA or UL is imperative and will protect you from purchasing a poser. Look for models that state they are certified for use in your specific NFPA classified environment. This provides legal certification and ensures that every component in the vacuum from the ground up meets strict standards for preventing shock and fire hazards.

Explosion-Proof Vs. Intrinsically Safe

In environments where electricity is unavailable or undesirable, pneumatic vacuums for hazardous locations are excellent alternatives. It is important to note that only electric vacuums can be certified and deemed “explosion-proof,” but properly outfitted pneumatic vacuums, referred to as “intrinsically-safe,” often pack the same punch as their electric counterparts while still meeting the requirements for use in your NFPA classified environment. Again, beware of companies that refer to their pneumatic models as certified explosion proof. Testing agencies for air-operated machines simply do not exist.


As with any critical environment vacuum, superior filtration should not be sacrificed on an explosion proof model. For peak operating efficiency, the vacuum should have a multi-stage, graduated filtration system, which uses a series of progressively finer anti-static filters to trap and retain particles as they move through the vacuum. For companies of all shapes and sizes, the use of HEPA filters is not just critical, but mandatory. Quality HEPA filters offer an efficient, effective way to trap and retain the smallest dust particles, down to and including 0.3 microns, helping to preserve air quality and protect workers. Manufacturers also have the option for an ULPA filter, which captures particles down to and including 0.12 microns. In order to eliminate combustible dust from being exhausted back into the ambient air, the HEPA or ULPA filter should be positioned after the motor in order for it to properly filter the exhaust stream. The motor’s commutator and carbon brushes generate dust, and if the exhaust stream is not filtered, that dust will simply be released back into the environment.

Spill Response

Don’t forget to take spill response into account when purchasing an EXP. Although OSHA’s current audits are specifically looking at companies that handle dry solids, manufacturers’ maintenance plans are also under the microscope. If you plan on collecting flammable or explosive chemicals, consider a wet-model explosion-proof vacuum, which are also available in both electric and pneumatic versions.


Picking the right vacuum often raises a lot of questions, especially when it comes to disaster prevention. Ask your vacuum-manufacturer to do an onsite analysis of your vacuum needs in order to recommend what type of vacuum, hose and accessories you should use.

As displayed in one too many plants all across the U.S., the term “maintenance” oversimplifies the role an industrial vacuum system plays in today’s manufacturing processes. The right vacuum can save money, protect the integrity of the product, increase productivity, and most importantly, protect your most valuable asset, your employees.

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