Is Combustible Dust Present in Your Workplace?

Industrial Vacuum Systems for Use in Hazardous Locations or Ordinary Locations with Combustible Dust

Combustible dust in manufacturing environments has always been one of the major threats for Health and Safety managers. They are responsible for preventing any possible dangers associated with workers and production plants. Many accidents have happened in the past, but after the Imperial sugar disaster in 2008, where 14 people died as a result of an explosion caused by sugar dust, world organizations were sensitized to the creation of new standards and policies preventing such disasters. Starting from that event, OSHA (Occupational Health and Safety Administration) and the NFPA (National Fire Protection Association) started to develop monitoring programs for North America in order to assure the maximum safety level possible in industrial manufacturing processes. Industrial vacuum systems were unavoidably involved in these new policies as they represent both:
✓ Possible source of ignition, if not properly equipped
✓ The best solution and recommended cleaning method for removal of hazardous dusts

HOW DOES A DUST EXPLOSION OCCUR?

An illustration known as the "Explosion Pentagon" shows the elements needed to cause seemingly harmless dust to explode.

Environment Classification – NFPA 70 / Nec

Which policies were created to protect facilities from hazardous dust risks?

NFPA set a classification of dangerous environments based on the type of risk and on its frequency in presence of combustible dust. Two other regulations (NFPA 654 - Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids and NFPA 484 – Standard for combustible metals) both define combustible dust as “any fine solid material that is 420 microns or smaller in diameter and present a fire or explosion hazard when dispersed and ignited in air”. This is why even non classified environments must comply to the housekeeping and cleaning regulations. Not only the generally recognized hazardous industries as pharmaceutical and petrochemical industries are vulnerable to hazard dust explosions, but also agriculture and food industries; such as feed, flour, candies, spice, coffee, tobacco, grain, fertilizer, plastics, wood, paper, pulp, textiles, furniture, tire and rubber manufacturers, dyes, coal and metal processing (aluminium, iron and zinc).

STANDARD ON THE FUNDAMENTALS OF COMBUSTIBLE DUST – NFPA 652

The NFPA created its own regulation in order to set standards to deal with combustible dust in industrial environments, the NFPA 652. The NFPA 652 applies to all facilities that manufacture, blend, package, repackage, convey, or handle combustible dust or particulate solids that may become dust (even in presence of not classified environments) and states that each plant must have:
✓ On file a copy of their dust type testing
✓ A complete Dust Hazard Analysis in order to prevent dust related hazards.
✓ Documented housekeeping procedure listing these methods of cleaning in order:

1. Properly equipped industrial vacuums
2. Brooms, mops
3. Blowguns (only where ignition sources are not present)

Industrial vacuum cleaners are listed as the preferred method of cleaning as they collect and contain dusts safely, guaranteeing the highest level of cleaning and hygiene (much more than blowing or alternative cleaning systems).

NATIONAL EMPHASIS PROGRAM – OSHA

OSHA gives a guidance that all industries must follow called NEP (National Emphasis Program), which lists recommended housekeeping and maintenance procedures.
Even if the NEP is not an approved regulation, this does not mean that it can considered without penalty. There are some standards that can be used for regular citations.
The recommended procedures include:

✓ Detailed working environment cleaning program, defining the materials which may be combustible, the processes to avoid explosions, hidden areas in the facilities that have to be checked regularly, source of ignition
✓ Use of industrial vacuum systems as the best and safest choice for cleaning
✓ Only use certified equipment for the scope, both as outlined by the environment (HazLoc) or for safely picking up the dust type (Combustible / Non-combustible) as identified in your Dust testing and DHA.

Certified or compliant to NFPA and OSHA standards?

It is not possible to certify any equipment or vacuum cleaner by NFPA or OSHA standards, because they are not certification authorities. Only an NRTL (Nationally Recognized Testing Laboratory) may certify equipment for use in Hazardous Locations. The NFPA and OSHA provide specifications that vacuum cleaners (and general equipment) must have when collecting combustible dust. An industrial vacuum cleaner can only be compliant to NFPA and OSHA standards, and it happens when it features:
✓ Complete earth grounding
✓ Conductive accessories, correctly bonded to be safe
✓ The fan must be well protected from the dust particles
✓ Antistatic filters
✓ There is no paper filter
✓ Specific Ohm testing for each part of the machine must meet the criteria outlined in the standards for each dust type or environment.

EXPLOSION PROOF CERTIFICATION

Only electrical equipment can be certified and the only authorities able to do that are the NRTLs (Nationally Recognized Testing Laboratory). They are the only bodies that can provide certifications for electric equipment in the United States.
Note: Pneumatic equipment cannot be certified by a NRLT, because there is no certification for pneumatic equipment in the United States.