By Braun Intertec | August 13, 2020

Combustible dust is one of the most overlooked workplace hazards and has the potential to be one of the most dangerous. According to the U.S. Chemical Safety and Hazard Investigation Board, from 1980 to 2005 there were 281 combustible dust incidents that left 119 dead, 718 injured, and caused extensive property damage to industrial facilities. Under the OSH Act of 1970, OSHA requires employers to furnish employees a place of employment free from recognized hazards that are causing or are likely to cause death or serious physical harm. OSHA may cite an employer under the OSH Act (more commonly referred to as the General Duty Clause) if employers have not taken measures to address the hazards associated with combustible dust. The National Fire Protection Association (NFPA) 652 Standard on the Fundamentals of Combustible Dust provides requirements for identifying and managing the fire and explosion hazards of combustible dusts and particulate solids.

Identifying and Controlling Dust Hazards

The NFPA 652 Standard was set up to promote and lay out guidance for hazard analysis, awareness, management, and mitigation and introduced the idea of a Dust Hazard Analysis (DHA), an abbreviated version of a Process Hazard Analysis (PHA) that is specific to dust hazards. This standard can be used by employers to recognize and address hazards associated with combustible dust. Since the effective date of the NFPA Standard, the deadline for at risk employers to complete a Dust Hazard Analysis (DHA) on existing processes has been extended from November 2018 to September 7, 2020 for existing processes and compartments. DHAs are expected to be completed as part of the design phase of new processes. As of now, the only industries that have an extension are the food and agricultural facilities that comply with NFPA 61, and they must complete a DHA by January 2022.

DHAs include a systematic review of your processes to identify the presence of combustible dusts, while identifying where these hazards exist, site-specific hazards, existing and recommended safeguards, and an implementation plan. It should be noted that the NFPA 652 standard also specifies that DHAs must be re-evaluated every 5 years.

What Causes Dust Explosions?

Dust explosions are caused by five essential factors, often called the “Dust Explosion Pentagon” which include: oxygen, ignition source, dust (fuel), dispersion of the dust, and confinement of the dust. When all these factors are present there is a significant chance that an explosion will occur. Typically, there is a primary explosion that although not strong, often leads to a secondary explosion, which can be much more powerful with severe impacts. Secondary explosions are caused by the ignition of accumulated dust (floors, equipment, ducts, ledges, etc.) being dispersed into the air by the pressure wave of the primary explosion. Sometimes, there is a chain reaction that can cause multiple explosions.

Braun Intertec can help ensure you are in compliance with the new standard, and at the same time help prevent a major incident that has the potential to cause catastrophic damage and loss of life. Our consultants can provide a comprehensive DHA that identifies potential sources of combustible dust, ignition sources, dust analysis, and recommend procedures to keep your workplace safe.