British Columbia Combustible Dust Hazards Awareness Workshops

Workplace combustible dust related fires and explosions occur with alarming regularity in the global grain, mining, forestry and manufacturing sectors. Although the majority of incidents do not result in fatalities, injuries, or property damage, historically many of these non-consequential incidents have been precursors to catastrophic events.

The complex topic of combustible dust hazards recently came to the forefront in British Columbia when WorkSafeBC issued a directive order for all sawmills to conduct a comprehensive risk assessment resulting in an effective dust control program. 

In conjunction with FireWise Consulting Ltd., John Astad, Director and Research Analyst from the Combustible Dust Policy Institute (CDPI) will be presenting a series of one day Combustible Dust Hazards Awareness Workshops throughout British Columbia. The goal of the CDPI is to minimize the severity and reduce the occurrence of combustible dust related fires and explosions through research of combustible dust related incidents. For more information on the CDPI  view brochure here.

The Combustible Dust Hazards Awareness Workshop will provide stakeholders with the knowledge to minimize the probability of occurrence and severity of consequence of future combustible dust related incidents. In addition the workshop will assist stakeholders in developing a comprehensive dust control program as noted in the revised WorkSafeBC OHS Guidelines. Key aspects of the workshop are identifying, evaluating, and controlling combustible dust hazards in addition to providing guidance in conducting facility inspections and risk assessments.

Facility owners and managers concerns in reducing the probability of a catastrophic secondary dust explosion include good housekeeping, employee training, maintenance, and management of ignition sources. Prevention of future incidents begins with awareness of the problem and a robust hazard mitigation framework which consists of a facility risk assessment, written combustible dust program, and hazard communication.

This combustible dust workshop will discuss the importance of these topics and more in addition to the BC Fire Code referencing the National Fire Protection Association (NFPA) combustible dust standards. NFPA best industry practices include engineering controls for deflagration suppression, deflagration isolation, and explosion venting in the mitigation of combustible dust explosions. The NFPA 664 Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities provides excellent guidance in this area and is a key resource for the workshop.  Click here for a detailed course outline.

COURSE DETAILS


June 11, 2012  Prince George

June 12, 2012  Williams Lake

June 14, 2012  Vernon

June 18, 2012  Port Alberni

June 19, 2012 Township of Langley


Time: 0800 to 1600
Registration Fee: $149.00 plus tax (includes lunch)

Register on-line by clicking on the FireWise Consulting Registrations link or register by mail, e-mail or fax by printing and filling out the form at the following link: Registration Form

Understanding the WorkSafeBC Lakeland Mills inspection reports

Recently there has been extensive media coverage on the recently released WorkSafeBC Lakeland Mills inspection reports. Media accounts mention dust levels in the reports but fail to inform the public that the issue of dust was primarily respiratory health hazards of dust and not fire and explosion hazards of dust. There is a big difference. In many instances airborne levels of combustible dust can be indicative of engineering control measures such as local exhaust ventilation is not adequate or insufficient housekeeping.

Excerpts from Lakeland Mill Report

 

This inspection report focused on the MSI, Noise and Wood dust components of the provincial high risk strategy.

2/3/2009 page 33 Most processing saws and chipping heads are equipped with local exhaust ventilation, which appear to reduce accumulations of fine dust. No recent monitoring of exposure to wood dust has been conducted. Wood dust exposure will be further evaluated during subsequent inspections.  This is an item that should be re-evaluated due to the changes in productivity that has occurred over recent years and the fact the majority of the wood being processed is dry beetle killed pine

 

SRO/OHO Barry Nakahara and I inspected this worksite as part of the high risk provincial strategy

5/27/2010 page 67 We confirmed that hearing tests are being done regularly. We discussed potential dust exposure and the need for appropriate respiratory protection for workers performing clean up of dusty areas. The employer has recently conducted air monitoring for dust and exposures relating to the end-spraying operation. These results were reviewed and no significant problems were noted.

 

OSO Darren Beattie and I conducted an inspection of this jobsite on February 6, 2012 to assess compliance with the Workers' Compensation Act and the Occupational Health & Safety Regulation. A separate inspection report will be issued by OSO Beattie summarizing his observations.

2/9/2012 Page 112 We discussed the wood dust observed throughout the mill. At the time of inspection, the airborne concentration appears to be below the exposure limit (Non-allergenic wood dust EL = 2.5 mg/m3) in the work areas visited.  There are accumulations of piles of wood dust in various areas of the mill. We reviewed the requirement to prevent the accumulation of hazardous amounts of wood dust.

Resource
Lakeland Mills inspection reports

Guidance WorkSafeBC Directive Order to Sawmill Employers

Now that the topic of workplace combustible fire and explosion hazards is out the open in British Columbia  sawmills it is important for facility owners and managers to understand the steps in a risk assessment in developing engineering and administrative control measures. The missing link that has not been communicated to stakeholders is the importance of understanding the BC Fire Code which references NFPA 664 Standard for the Prevention of Fires and. Explosions in Wood Processing and Woodworking. Facilities. An excellent resource in understanding NFPA 664 is the 24 page .pdf document developed by the  Wood Machinery Manufactures of America (WMMA).


The BC Fire Code references NFPA 664 Standard for the Prevention of Fires and. Explosions in Wood Processing and Woodworking. Facilities. For example,  BC Fire Code (1998), Hazardous Processes & Operations (page 113 .pdf) Section Part 5.3. – Dust Producing Processes (page 115 .pdf)

Many don't realize that it is not WorkSafeBC which enforces the BC Fire Code but instead the Fire Commissioner ("Office") and the Office's jurisdiction over fire safety and fire protection in British Columbia. The Office is the senior authority having jurisdiction over fire safety and prevention in B.C. The Office administers the Fire Services Act and it regulations, and appoints and trains local assistants to the Fire Commissioner.

"where WorkSafeBC prevention officers observe what they believe to be a violation of the Fire Services Act or its regulations, prevention officers will notify the local assistant to the Fire Commissioner."

Solely relying on the WorkSafeBC regulation on combustible dust is not sufficient in undertaking a comprehensive risk assessment in addition to developing a combustible dust control program. An understanding of NFPA 664 as referenced in the BC Fire Code will assist immensely in conducting a safety review for combustible dust in sawmills.

To assist stakeholders WorkSafeBC published OHS Guideline G5.81 Combustible Dust-Sawmill Facilities (April 25, 2012) The recent guideline provides information on a Combustible Dust Program which includes elements of hazard mitigation; facility risk assessment, written combustible dust control program, and a hazardous communication program.

Update April 28, 2012 WorksafeBC Bulletin — Clean-up of hazardous combustible dust
"WorkSafeBC has prepared a simple one-page bulletin in safe cleaning procedures of combustible dust that  protect workers."

Resources 
WorkSafeBC Directive Order to Sawmill Employers 
NFPA 664 Combustible Dusts – Overview (WMMA)
BC Fire Code (1998)
OHS Guideline Combustible Dust Sawmills

Mystery of Airborne Combustible Dust Concentrations

So at what threshold should airborne concentrations of combustible dust trigger a concern for combustible dust related fires and explosions? Mention of industrial hygiene issues is reminiscent of the 2011 Foxconn catastrophic dust explosion in China, where initially workers complained of high levels of aluminum dust respiratory exposure during polishing operations.

Confusion still exists according to media accounts of the high airborne dust levels discovered in the WorkSafeBC inspections at the British Columbia, Canada facility a few weeks prior to Fridays catastrophic explosion. These high levels were for airborne concentrations in regards to respiratory exposure not combustible dust explosive concentration levels. Explosive airborne dust concentrations would require approximately 30,000 times more than the concentration found in the inspections depending on moisture content and particle size. For example, the highest airborne concentration was 5.9 milligrams/cubic meter, which was 2 times over the acceptable threshold of 2.5 milligrams/cubic meter, according to WorkSafeBC inspection reports released to the media.

To put this into perspective we must ask what exactly is 2.5 milligrams? Well if you put a pesky mosquito on a laboratory scale that would be your answer. Of course mosquitoes are not processed in sawmills, lumber is. But this does provide a general idea of 2.5 milligrams of mass. Alternately, using the mass of wooden toothpick provides better idea of how high suspended dust concentrations would be in one cubic meter of volume, such as the volume of a huge glass fish tank.

So here is the math. On an average, a wooden toothpick weighs approx. 100 milligrams on a laboratory scale. Now dissect the toothpick into 40 parts, which would equate to each of the forty toothpick parts weighing the same as a 2.5 milligram mosquito.

Now take three of those individual 2.5 milligram toothpick parts and grind them up to the consistency of sawdust. This would provide about total 7.5 milligrams of mass, a little over the 5.9 milligrams of the high airborne dust level that inspectors found in a cubic meter during the prior facility inspection.

So one must ask, is approx. 1/10 of wooden toothpick sawdust explosive in a cubic meter volume of air? The basis of a combustible dust explosive atmosphere is that the minimum explosive concentration (MEC) must be sufficient to have ignition while in suspension when combined with the fire triangle.Think of MEC analogous to the lower flammable/explosive level LFL/LEL of a flammable vapor or gas.

In contrast a minimum explosive concentration (MEC) of sawdust depending on moisture content and particle size is approximately 300 wooden toothpicks, weighing approximately 30 grams or 30 grams/cubic meter.Hope this helps obtaining insight in the difference between airborne respiratory hazards (milligrams) in contrast to airborne explosive concentrations (grams) of combustible dust. Of extreme importance is to ensure horizontal layers of dusts do not become airborne where a safe respiratory concentration can escalate rapidly into a minimum explosive concentration (MEC). Good housekeeping is key in this respect.