State officials are investigating a recent combustible dust flash fire that killed one employee and injured two others at Advanced Environmental Recycling Technologies (AERT) in Springdale, Arkansas. Although the cause of the fire is being investigated, Assistant Fire Chief Kevin McDonald said that the fire initiated in a mixer during production. “The dust associated with the type of process that goes on here resulted in some type of a flash fire that encapsulated three of the employees,” McDonald said.

McDonald went on to say, “We’ve experienced fires before, not only in those mixers, but also the dust accumulations throughout the facility,” McDonald added. “Anytime we disturb it with our hose streams, more often than not, we do more harm than good…a lot of the areas where we can’t really access the product that’s in there, the dust accumulation just has to burn away. Every time we have a fire, AERT tries to learn from what we discover, what caused it, and take measures to prevent those kind of fires again.”

According to Dwayne Miller, of the Springdale Fire Marshal’s Office, this fire is one of 18 calls made to the factory since 2004. He said that most of the fires have occurred in the same area of the factory – an area where wood and plastic particles can build up within the air.

The last fire reported at the facility was in February 2012, when a dust explosion blew the roof off of a silo. No injuries were reported in the incident. According to AERT, since then, they have taken steps to help prevent incidents.

The fire department’s incident report confirms that this most recent flash fire exited from the top of two production mixers into the penthouse enclosure on the roof located directly above the mixers. According to witness statements, several workers were changing out slide gates above the mixers while the mixers were running. A worker noticed a fire inside the equipment through an open bolt hole, and applied water through the hole in an attempt to extinguish the fire. The application of water resulted in a flash fire, which exited the equipment enclosure into the confines of the penthouse, engulfing the workers.

Several familiar lessons can be learned from this incident:

  • Process equipment that contains combustible materials, including combustible dust, should be shut-down, and cleaned of all combustible materials before performing any maintenance activity.
  • Applying water to a fire within enclosed equipment that contains combustible fines and powders is inherently dangerous and should be avoided because the water application can disturb combustible powders and rouse them into a flammable dust cloud, which can result in a flash fire or explosion. Generally, it is safer to shut down the equipment and use firefighting equipment to protect the exposures, allowing the fire inside the equipment to burn itself out.
  • If workers in the factory will routinely be exposed to flash fire hazards as part of their expected work duties, the workers at risk should be provided with and wear flame-resistant garments that comply with the requirements of NFPA 2112, Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire.
  • Any factory that handles, processes, or produces combustible dusts—and especially a factory with this reported history of combustible dust incidents—would be well-advised to retain the services of a qualified expert to regularly audit the plant for combustible dust fire and explosion hazards and provide recommendations for mitigating those hazards in accordance with applicable NFPA combustible dust standards. The expert should also be retained to provide general awareness training on combustible dust explosion risks to the plant’s management, operations, and maintenance personnel.
  • A factory should identify unique fire risks, develop specific emergency response plans for each risk, and thoroughly train key associates from operations, maintenance, and the emergency response team. This will help ensure the activities of operations and maintenance personnel are performed safely and do not start fires. This will also help ensure that incident responses by the emergency response team are carried out with personnel safety as the primary goal.

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By Jeff Harrington, CEO and Founder of Harrington Group, Inc.