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Is Your Dust Combustible? Dust Testing Under NFPA 652

Posted on October 12, 2016

Have you tested your dust? If not, it’s time to get on that. Under the recently released NFPA 652: Standard on the Fundamentals of Combustible Dust, material explosivity testing is now a requirement for all facilities that generate, handle, or store dust.

This means if you have dust in your facility, it’s your responsibility to have the dust tested for combustibility, even if there’s no history of your type of dust causing a combustible dust incident.

What does dust testing entail?

A dust test is a comprehensive evaluation that should be done by a qualified laboratory with the expertise to not only test the dust, but also analyze and explain the results as well as provide the required compliance documentation.

There are five main factors that a dust test should evaluate:

Dust cloud explosibility parameters (Kst, Pmax)

These parameters quantify the severity of a dust explosion. Together, they tell you how much pressure an explosion will generate and how fast it will travel.

  • Kst indicates the rate of pressure rise of a combustible dust.
  • Pmax indicates the maximum explosion pressure of a dust cloud.

Dust cloud ignition limits (LOC, MEC)

These two parameters tell you the likelihood that a dust cloud will explode based on the concentration of oxygen and dust.

  • Limiting oxidant concentration (LOC). The LOC is the minimum oxygen concentration that can support a dust cloud explosion.
  • Minimum explosible concentration (MEC). The MEC is the minimum concentration of dust in the air that will explode if ignited.

Auto-ignition temperature (MAIT)

This test assesses a dust’s sensitivity to heat. The minimum auto-ignition temperature (MAIT) is the lowest temperature at which a dust cloud will auto-ignite when exposed to hot air.

Minimum ignition energy (MIE)

This test determines the smallest amount of ignition energy required to ignite a dust cloud.

Dust layer ignition temperature (MIT)

This test finds the minimum temperature required to ignite a dust layer on a hot surface. For example, the MIT for a 5-mm layer of a combustible food dust will be different from the MIT for a 5-mm layer of a combustible wood dust.

The results of these dust tests determine your further responsibility under NFPA 652. If the dust is found to be combustible, you must then perform a dust hazard analysis (DHA) and take steps to mitigate those hazards.

How Nilfisk can help

For many companies, the dust testing step is new. Our goal at Nilfisk is to help you through the entire process, from facilitating your dust testing to helping you select NFPA-compliant products so you can mitigate your risks.

Here’s how we can help:

  • Facilitating your dust testing (we don’t provide the testing ourselves, but we can help you obtain it through our collaboration with the fire and explosion experts at Fike)
  • Performing site assessments
  • Demonstrating cleaning equipment on-site
  • Helping you select NRTL-certified and NFPA-compliant products
  • Setting up your new equipment and providing training for you and your employees

Learn more about our complimentary support services in our Dust Testing Datasheet. We look forward to helping you stay safe and compliant!