Combustible dust affects nearly all manufacturing plants and needs a mitigation plan meeting all codes or standards, with input from the local authority having jurisdiction (AHJ), insurance carrier or internal company safety protocols.
The NFPA is the governing body issuing the rulebook regulating combustible dust concerns and providing explosion protection design advice. They have published industry specific regulations on how to handle combustible dust and related issues. These regulations are based on studies, findings, input from experts, and are frequently updated.
Before making changes to existing dust collection systems or equipment, your engineer needs to review applicable codes to ensure compliance.
Whatever trhe final design and equipment selection, it is imperative to know who will approve or certify the selected system once it is up and running. That party is the AHJ and most often will refer to the latest version of the NFPA Standard.
Those NFPA Standards we routinely see associated with industrial dust collection systems are the latest edition of the following:
NFPA 61: Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities – An industry specific Standard that is directed at protecting Agricultural and Food Processing Facilities. It focuses on methods of safely handling agricultural dusts, by-products, and related materials, through maintaining certain safety precautions regarding their storage, handling and processing. Storage silos and bucket elevators are typical equipment covered by this Standard.
NFPA 68: Standard on Explosion Protection by Deflagration Venting – This Standard defines methods for implementing explosion vents or systems to decrease pressures within a dust enclosure to minimize damage, should flammable vapors or dusts be ignited. All the other standards refer to NFPA 68 when it comes to venting. Vent panels are most commonly found on dust collectors, baghouses, bucket elevators, silos and cyclones. Explosion vents are the most cost-effective means to control a deflagration if the conditions allow it. Vessel strength, explosibility of dust, location of vessel, and toxicity of materials being collected are all parameters to be considered in the final design.
NFPA 69: Standard on Explosion Prevention Systems – This Standard serves as a guideline for designers or AHJs who are responsible for explosion prevention systems implemented on process systems that produce flammable gases, dusts or hybrid mixtures. This Standard is the basis of protection system designs including explosion suppression and explosion isolation. Typical equipment requiring compliance include spray dryers, dust collectors, baghouses, cyclones, bins, product receivers, fluid bed dryers and flash dryers.
NFPA 484: Standard for Combustible Metals – This industry specific standard applies to those manufacturers involved with processing, finishing, and recycling of metal or metal alloys that generate a byproduct of fugitive combustible powders or dusts and are capable of exploding. This is the strictest NFPA guideline as it relates to combustible metals. It is highly recommended to have an expert aid in system design and protection implementation, as NFPA 484 contains endless minutiae that cannot be avoided. Typical applications are product milling and dust collectors.
NFPA 652: Standard on the Fundamentals of Combustible Dust – This Standard defines the key elements of potential combustible dusts explosions or fires and the necessary mitigation procedures to avoid them. It acts in conjunction with industry specific Standards by allowing them to prevail in specification conflict. This standard has a correlating committee working with the industry specific standards to get all the standards on the same page. Understanding of 652 is very important to plant personnel and design engineers working with combustible dusts. A key element of the Standard is the responsibility placed on facility management for knowledge of the dust which requires a Dust Hazard Analysis (DHA).
NFPA 654: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Solids – This NFPA Standard addresses the prevention and mitigation of explosions or fires for all combustible solids in particulate sizes including dust, fibers, chips, and chunks.
NFPA 664: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities – This industry specific Standard details mitigation techniques for the wood processing and woodworking industry to protect against fire and explosion. Process equipment needing protection include cyclones, dust collectors or baghouses.
Should your AHJ require additional documentation, SysTech can provide Combustible Dust Testing and recommend a Risk Assessment Consultant to evaluate and document the existence or non-existence of dust hazards within your facility, by conducting a DHA.
That’s it, the most requested Code questions we receive. In conjunction with IEP Technologies, we’re here to help!
With all that said, compliance to Code is very important but the overriding concern is your people first, so a few minutes of NFPA review is mandatory.