Do You Have Combustible Dust?

Combustible dust is a serious safety risk in many industrial environments. Compounding the danger is the fact that many facility managers do not even realize that their processes are generating combustible dust. If you have combustible dust, a devastating explosion or fire could occur at any time, without the proper mitigation and management measures in place.

Firemen putting out fire

What Types of Dust Are Considered Combustible?

Any fine dust or particulate that has the potential to ignite or explode is considered combustible dust. In an industrial environment, process dust collects on surface areas like ceilings, rafters, duct, and equipment rather quickly. When the dust is combustible, this accumulation creates an environment that is highly flammable and explosive. Activity within the area can disturb or ignite combustible dust, quickly leading to disaster.

Combustible dust can be created by processes involving metal, wood, sugar, grain, as well as many other organic and non-organic materials. The types of material that can become combustible may be surprising:

  • Agricultural Products and Dust (Sugar, Powdered Milk, Wheat Grain)
  • Carbonaceous Dusts (examples: Charcoal, Cellulose, Corn)
  • Chemical Dusts (Ascorbic Acid, Calcium Stearate, Sulfur)
  • Metal Dusts (Aluminum, Bronze, Iron)
  • Plastic Dusts (Epoxy Resin, Melamin, Vinyl)

NFPA & Combustible Dust Regulations

The National Fire Protection Association (NFPA) develops regulatory guidelines to promote safety, including requirements for combustible dust management. In 2015, NFPA 652 was issued, setting a new standard on the fundamentals of combustible dust. The standard relates to industry-specific standards and assures that standard requirements are consistently applied across industries, processes, and dust types. A new development in October 2018, removed previous exceptions that allowed certain industries to be grandfathered into compliance.

Dust Testing Identifies Combustible Dust

In some cases, documentation may be available to help you determine if the dust in your facility is explosive. When documentation is not available, dust testing of your materials should be done at a facility using ASTM (American Society for Testing and Materials) and ISO (International Standard Organization) procedures.

Dust testing will officially determine if dust or powder produced by process applications is potentially combustible. The test results will determine if a material is classified as Type A — Explosible — or Type B — Non-Explosible.

Dust Testing Factors

The following factors are evaluated during dust testing and will help determine the appropriate dust collector and explosion isolation equipment selections.

Kst – the rate of combustion and dust deflagration index, which measures the relative explosion severity compared to other dusts. The larger the value for Kst, the more severe the explosion. Kst provides the best “single number” estimate of the anticipated behavior of a dust deflagration.

Pmax – the maximum explosion overpressure generated in the test chamber.

Mean Particulate Distribution Size – the smaller the particle, the more combustible the dust is, unless the particle is too small for combustion to occur.Used to determine appropriate filter selections.

MEC – the minimum explosible concentration, which measures the minimum amount of dust dispersed in air required to spread an explosion.

MIE – the minimum ignition energy, which predicts the ease and likelihood of ignition of a dispersed dust cloud.

LOC – refers to limiting oxygen concentration. Used to determine the minimum percentage of oxygen required to support a combustion

Moisture Content – refers to the percentage of moisture in material. The drier the dust, the more combustible the dust

Air Solutions is Your Source for Combustible Dust Solutions

Our team along with our associates are experienced and qualified to assist you with NFPA combustible dust compliance, from dust testing to evaluating vulnerabilities at your facility. We develop advanced explosion protection systems that address the needs of your specific facility and processes.