Combustible Dust: Understanding NFPA 654
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Combustible Dust Services: Understanding NFPA 654

Combustible Dust Services | Combustible Dust Solutions

Combustible dust explosion is a critical concern for any company that processes and conveys dry bulk materials in their production facility. Changes in regulations have brought this issue into even greater focus. Nol-Tec Systems are the experts in developing combustible dust solutions that minimize the production of dust and the possibilities of combustion.


Contact Nol-Tec to discuss combustible dust solutions for your workplace.


Recent Combustible Dust Regulation Updates

The National Fire Protection Association (NFPA) recently issued stricter standards for safety measures used to prevent and mitigate explosions and fires in facilities where a combustible mix of dust/air could be present. Some of these changes include the particle size that defines dust (material less than 40 mesh) and the inclusion of more organic materials.


Additionally, the United States has fully adopted the Globally Harmonized System for the Labeling and Classification of Chemicals (GHS), which set new standards for combustible dust. (These standards are also incorporated into the NFPA recommendations.) These changes mean the reach of the codes has changed substantially.


NFPA Combustible Dust Codes

There are several NFPA codes that pertain to combustible dust, but it is the intent to have standards address consistently across industries and materials. Nol-Tec has broad experience in conveying materials in all of these categories.

  • NFPA 652 – general regulation which directs users to the more specific industry and commodity specific standards
  • NFPA 654 – manufacturing, processing, and handling – broadest regulation and the base for the others
  • NFPA 61 – agricultural and food processing (organic dusts)
  • NFPA 484 – combustible metals
  • NFPA 655 – sulphur
  • NFPA 664 – wood processing and woodworking


Many chemicals not previously classified as hazardous are now designated as combustible dust explosion hazards. The Kst (dust deflagration index) values of a myriad of powders have been updated.


The Kst value indicates how easily a material or mixture ignites, what the speed of fire/explosion propagation is, and the amount of energy released in the explosion. It measures “relative explosion severity compared to other dusts” (OSHA’s Hazard Communication Guidance for Combustible Dusts, OSHA 3371-08 2009). These are all indicators of the severity of a combustible dust explosion caused by a given material. In fact, so many dusts are classified combustible that the focus is now on that severity potential and how to mitigate it.


High-Profile Combustible Dust Explosions Lead to Stricter OSHA Enforcement

In late 2014, the Occupational Safety and Health Administration (OSHA) received a mandate to fully enforce these updated NFPA standards, covering hundreds of chemicals, organic materials, metals, and powders. This stricter enforcement has been, in no small part, due to several high-profile combustible dust explosion incidents.


The United States Chemical Safety Board (CSB) investigates these accidents and issues final reports and recommendations for any facility that hopes to reopen and continue working with combustible dust. Their findings can also be very informative for other similar facilities working to minimize combustible dust explosion potential in their own plants. Examples of this reporting can be found at the U.S. Chemical Safety board website, along with a video showing how dust combusts and the damage it can inflict on a facility and its staff.


Along with these CSB recommendations, OSHA utilizes NFPA 654 to inform site inspections for violations such as poor housekeeping, inadequate communication of the hazards posed by a material, and insufficient hazard control.


Hazard control has typically been focused on two areas. The first is facility housekeeping and containment of the materials. Nol-Tec is an expert in handling difficult bulk materials—those that are fragile, friable, or abrasive. We know how to design combustible dust solutions that minimize breakage of your materials. Less breakage means less dust, which means less risk for combustible dust explosion. And, the less dust that escapes the conveying process, the lower the risk of explosions due to accumulations of dust in the facility. Nol-Tec Systems’ dense and dilute phase pneumatic conveying designs are fully enclosed and are reliable tools for the maintenance of a clean facility.


Explosion Mitigation: Preventing Combustible Dust Explosion

The second focus area of OSHA’s hazard control regulations is on the mitigation of combustible dust explosions. This is generally accomplished through the use of explosion panels, venting systems, and/or explosion suppression systems. Panels and venting can help control the release of energy in case of an explosion, which can minimize damage to the plant and improve personnel safety. There is, however, damage to the processing system itself, as well as loss of the dry bulk material that exploded and burned in that contained circumstance.


Combustible dust explosion suppression systems release suppressing chemicals into the convey system when potential explosive conditions are detected by a pre-programmed safety system. Combustible dust solutions like these will stop the explosion, but the material and the convey lines are contaminated. The material must be discarded and the convey lines scrubbed, costing time and money.


Nol-Tec and Air Products and Chemicals have partnered on research for a system that would prevent combustible dust explosions by using inert gases as the conveying media, rather than oxygen.  Removing the oxygen from a dust/air mixture means no explosion is possible for the vast majority of compounds. Nol-Tec and Air Products and Chemicals co-authored a paper on the subject that was published in the March 2015 issue of Chemical Engineering. Further details on this research and its practicality for conveying combustible dust materials can be found here.


Contact Nol-Tec For Combustible Dust Solutions

Nol-Tec’s test lab and design staff are actively implementing NFPA 654 and GHS standards in our own facility and incorporating them into our design work. With over 30 years in the industry, Nol-Tec is in an exceptional position to understand the broad impact on our customers’ businesses. We have been updating our designs and recommendations to meet the challenges of these new regulations. 


Contact us today for customized combustible dust services that will make your facility safer.