Preventing Fire & Dust Explosions: NFPA 654

“NFPA 654 is a great place to start when taking steps to identify hazards and developing action items designed to reduce risk within a facility handling explosible or combustible materials.  There are NFPA codes specific to an industry, but NFPA 654 covers all other processes where combustible material is present.”

Fauske & Associates, LLC., 1-877-328-7531, https://www.fauske.com/chemical-industrial/testing/combustible-dust

History

NFPA 654, the “Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids,” is an all-encompassing standard on how to design a safe dust collection system. This standard also points people to more direct standards that deal with different types of dust and explosion protection equipment.

In the U.S., OSHA and the National Fire Protection Association (NFPA) regulate combustible dust issues, each with its own area of responsibility. OSHA, together with local authorities, enforces the NFPA’s combustible standards. OSHA’s Combustible Dust National Emphasis Program (NEP) outlines policies and procedures for inspecting workplaces that create or handle combustible dusts that have the potential to cause a deflagration, fire or explosion.

The Standards Council of the National Fire Protection Association (NFPA), Quincy, Mass., issued the 2013 revision of the NFPA 654 “Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids.” This standard applies to all combustible particulate solids or hybrid mixtures, regardless of concentration or particle size, where the materials present a fire or explosion hazard. The owners or operators of affected facilities are responsible for implementing the requirements.

Some of the changes in the past 15 years include administrative controls, such as safety-management practices; added training requirements for contractors and subcontractors; and incident investigation and reporting requirements. Important sections regarding housekeeping programs and hierarchy of clean-up operations also are included in the 2014 revision. Incident history and statistics clearly indicate that secondary dust explosions—caused by inadequate housekeeping and excessive dust accumulations—have cause much of the damage and casualties experienced in major industrial dust explosions.

Why Standard is Important

Dust explosions are an ever-present risk faced by process plants that handle combustible powders or other bulk solids. To minimize this risk and provide plant officials with practical requirements to protect against dust explosions, NFPA, in August 2005, first revised NFPA 654 to include Best Engineering Practice designed to protect facilities from combustible dust explosions. 

Combustible dust is any finely divided solid—such as flour, wood dust or coal dust—that will burn when dispersed in air and ignited. The standard identifies measures to be taken to avoid dust explosions by designing facilities and work practices that prevent the production and spreading of dust, as well as controlling ignition sources, and provides mitigation recommendations for explosions that cannot be prevented.

NFPA standards are typically adopted by state fire marshals, insurance companies and consultants. The standard applies to “all phases of the manufacturing, processing, blending, pneumatic conveying, repackaging and handling of combustible particulate solids or hybrid mixtures, regardless of concentration or particle size, where the materials present a fire or explosion hazard.” (paragraph 1.1.1) 

Key Compliance Requirements

The standard contains comprehensive guidance on the control of dusts to prevent explosions. The following are some of its recommendations:

• Minimize the escape of dust from process equipment or ventilation systems
• Use dust collection systems and filters
• Utilize surfaces that minimize dust accumulation and facilitate cleaning
• Provide access to all hidden areas to permit inspection
• Inspect for dust residues in open and hidden areas, at regular intervals
• Clean dust residues at regular intervals
• Use cleaning methods that do not generate dust clouds, if ignition sources are present
• Only use vacuum cleaners approved for dust collection
• Locate relief valves away from dust hazard areas
• Develop and implement a hazardous dust inspection, testing, housekeeping & control program (preferably in writing, with established frequency & methods)

When all of the recommendations of NFPA 654 are met and the potential for dust explosions is still present, an explosion-prevention system should be implemented where needed. 

Resources: 

• To purchase the standard, go to the NFPA catalog online store: https://tinyurl.com/h4eb48n5