Friday, January 14, 2011

Confined Structure Fires also Combustible Dust Related?

Just prior to the Christmas holiday a minor combustible dust related fire occurred in a dust collector at a Misc. Fabricated Metal Producing Manufacturing/NAICS 332999 facility in Wisconsin. These type of facilities are listed in Appendix D-2 of the OSHA ComDust NEP as Fabricated Metal Products, Not Elsewhere Classified with industries that may have Potential for Combustible Dust Explosions/Fires.

According to the news account:

The fire was extinguished and contained to the dust collector bag house. There was no fire extension into manufacturing plant.

The incident begs the question was this a confined structure fire? Where as in similiar small fire incidents that are limited in scope, are confined to noncombustible containers, rarely result in serious injury or large content losses, and are expected to have no accompanying property losses due to flame damage. The news account mentions no fire extension into manufacturing plant nor injuries which resulted in an estimated $10,000 damage to dust collection bag house. Since dust collectors are constructed of metal they would be non-combustible.

In the U.S. Fire Administration/National Fire Data Center, Investigation of Confined Structure Fires, Topical Fire Research Series, the report noted 2002 NFIRS 5.0 data contain abbreviated reporting for slightly over 52,000 confined structure fire incidents—37% of structure fires.These incidents accounted for $26 million in combined losses, 3 deaths, and nearly 500 injuries. Most confined structure fires (77.5%) occurred on residential properties. It is the other 23% that we are concerned about in manufacturing non-residential properties.

There is a problem in this US Fire Administration reporting in that it does not formally consider dust collectors or other process equipment in the manufacturing sector that are non-combustible as confined structure fires. Instead, cooking fires, trash or rubbish fires, chimney fires, commercial compactor, fuel burners, and incinerators are used as data element descriptors in these type of fires.

This does present a problem since fire service professionals can't identify combustible dust fire hazards in the NFIRS 5.0 reporting system, then how can they assist stakeholders in evaluating and controlling combustible dust fire hazards. All combustible dust related fires are failed catastrophic combustible dust explosions. Time is way overdue for the FEMA/US Fire Administration's National Fire Data Center to review their fire reporting methodology that omits the dozens of minor combustible dust related fires that have a history of evolving into catastrophic dust explosions.

Combustible Dust Explosion Pharmaceutical Preparation Plant

A combustible dust explosion occurred at a pharmaceutical preparation plant in Iowa prior to the end of the 2010 a few weeks ago. Luckily there were no injuries or fatalities and damage was minor according to the news account.

"There were no injuries. The explosion blew out doors on the building and dust collectors, with additional minor damage."
Eastern Iowa News Now

It appears the mention of doors blowing out in the dust collector might be referring to explosion ventilation panels. Being that the plant is involved in pharmaceutical preparation with a NAICS 325412, it is noted in the OSHA Combustible Dust NEP in Appendix D-1 as an Industries with More Frequent and/or High Consequence Combustible Dust Explosions/Fires.

Over the past 12 months OSHA has been enforcing a myriad of regulations in addition to ComDust NEP emphasis in their site visits at pharmaceutical preparation facilities. The OSHA Integrated Management Information System also referred to as IMIS provides a helpful insight to these inspections.

An educational General Duty Clause citation for one Pharmaceutical Preparation Plant noted that "neither dust collector was equipped with deflagration venting panels directed to an unoccupied area or with a suppression system. The collectors were located inside an occupied area which employees entered to conduct maintenance on a daily basis."This is in contrast to the current incident where the dust collector was installed outside on the roof and appeared to have explosion vent panels.

Results of an internet search produced a MSDS for microcrystalline cellulose (MCC) Cellulose; flour cellulose which has combustible dust fire explosion hazards. For example in the Fire Fighting section it notes, "Fine dust dispersed in air in sufficient concentrations, and in the presence of an ignition source is a potential dust explosion hazard. For Cellulose: Minimum ignition temperature, dust cloud: 410C. Minimum explosible concentration: 0.045 g/l." This is helpful information so stakeholders can take proper administrative, PPE, and engineering control measures.

On a side note, another combustible dust related fire and explosion originated from the same company that occurred nearly two weeks prior to above incident, yet paper dust was the process material at a different facility instead of microcrystalline cellulose (MCC) according to the news account.

“Something caused the paper dust to explode. We don’t know what it was,” Battalion Chief Rick Palmer of the Portage Fire Department said. Palmer said the fire department has been called to explosions at the plant in the past, most recently about eight months ago. Small fires can develop wherever the dust settles in the plant following such an explosion, he said. “We just chase little fires all over the place,”

Stakeholders searching the OSHA Combustible Dust NEP will not find any paper industries that OSHA believes have More Frequent and/or High Consequence Combustible Dust Explosions/Fires or Potential for Combustible Dust Explosions/Fires. Don't know what the NAICS is for the facility that generated paper dust in the news account yet there is mention that the facility produces paper insulation. In either case whether or not a facility is listed in the OSHA ComDust NEP, if you generate ComDust then you need to identify, evaluate, and control the fire and explosion hazards.


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