Thursday, April 17, 2014

Reducing the Risk of Dust Explosions by Controlling Electrical Ignition Sources

Event Registration (EVENT: 757605 - SESSION: 1)

Reducing the Risk of Dust Explosions by Controlling Electrical Ignition Sources Webinar Available On Demand

Date:April 3, 2014

Time: 11:00 AM PDT | 2:00 PM EDT

Duration: 60-minutes

Sponsored By:

About the webinar:

Dust explosions are a potential hazard in bulk solid manufacturing
and process facilities. Electrical ignition sources are routinely
identified as a possible cause during dust explosion investigations.

Attend this webinar and learn about:

  • Selecting the correct electrical equipment for dusty environments,
    and why the installation of the equipment must be directed by the
  • Applicable national codes and standards information you need for guidance when selecting electrical equipment.
  • Real world examples of appropriate and inappropriate electrical equipment installations.

Justin Bishop, Ph.D., P.E., CFEI

Managing Engineer

Exponent Failure Analysis Associates


Kevin Cronin


Powder & Bulk Solids

Monday, April 7, 2014

Safety workshop outlined dust’s risks before B.C. sawmill explosions

Safety workshop outlined dust’s risks before B.C. sawmill explosions - The Globe and Mail

The Babine sawmill is shown after the explosion and fire on Jan. 20, 2012. (WORKSAFE BC)

Safety workshop outlined dust’s risks before B.C. sawmill explosions

Wednesday, March 12, 2014

2014 International Biomass Conference and Expo

Come see us at the 2014 International Biomass Conference and Expo - Where I will be speaking on:

"Practical Prevention of Combustible Dust Fires and Explosions in Biomass Industry"

 International Biomass Conference and Expo

 Track 1: Pellets & Densified Biomass
Vital Safety Considerations for Manufacturers, Handlers, and Shippers of Wood Pellets
dust presents a very real safety hazard that must be fully understood
and carefully monitored if plant operators intend to keep their staff
and their facilities away from an unwanted occurrence. Additionally, as
the practice of stockpiling more and more woody biomass becomes routine,
an awareness of carbon monoxide offgassing is emerging as a leading
safety consideration wherever woody biomass is found in bulk. This panel
will provide pellet producers and pellet handlers with the information
they need to keep their operation a safe work environment.

  • Moderator: Cam McAlpine, President, PRMedia Strategic Communications
  • Mark Fecke, Managing Engineer , Exponent - Failure Analysis Associates
    Combustible Dust Risk Evaluation Made Simple
  • Tim Cullina, Senior Consulting Engineer, Fauske & Associates
    Hazard of CO Offgassing from Woody Biomass Storage
  • Jeff Nichols, Managing Partner, Industrial Fire Prevention LLC
    Practical Prevention of Combustible Dust Fires and Explosions in Biomass Industry 

2014 International Biomass Conference & Expo

The Conference & Expo

The 7th annual International Biomass Conference & Expo will take place March 24-26, 2014, at the Orange County Convention Center in Orlando, Florida. This dynamic event unites industry professionals from all sectors of the world’s interconnected biomass utilization industries—biobased power, thermal energy, fuels and chemicals.

Organized by BBI International and produced by Biomass Magazine, this event brings current and future producers of bioenergy and biobased products together with waste generators, energy crop growers, municipal leaders, utility executives, technology providers, equipment manufacturers, project developers, investors and policy makers. It’s a true one-stop shop – the world’s premier educational and networking junction for all biomass industries.

International Biomass Conference & Expo is where future and existing producers of biobased power, fuels and thermal energy products go to network with waste generators and other industry suppliers and technology providers. It’s where project developers converse with utility executives; where researchers and technology developers rub elbows with venture capitalists; and where Fortune 500 executives and influential policy makers sit side-by-side with American farmers and foresters.

International Biomass Conference & Expo is the largest, fastest-growing event of its kind. In 2014, this event is expected to draw nearly 1,600 attendees. In 2013, the event drew more than  1,200 attendees and doubling the attendance of the inaugural show. This growth is fueled by a world-class Expo and an acclaimed program.

Once again, the 2014 International Biomass Conference & Expo program will include 30-plus panels and more than 100 speakers, including 90 technical presentations on topics ranging from anaerobic digestion and gasification to pyrolysis and combined heat and power, all within the structured framework of five customized tracks:
Track 1: Pellets & Densified Biomass Track 2: Biomass Power & Thermal Track 3: Biogas & Landfill Gas Track 4: Advanced Biofuels & Biobased Chemicals

International Biomass Conference & Expo will help you – as a biomass industry stakeholder – identify and evaluate technical and economic solutions that fit your operation. It's time to tap into the revenue generating potential of sustainable biomass resources. Get started today by registering for the 2014 International Biomass Conference & Expo!

Wednesday, March 5, 2014

WorkSafeBC Combustible Dust Initiative Overview


WorkSafeBC Combustible Dust Initiative Overview

Richmond, B.C., March 4, 2014

— On January 31, 2014, WorkSafeBC concluded a three-month inspection of
all active sawmills across B.C. The inspections began November 1,
2013. These targeted inspections were in support of the ongoing
Combustible Dust Strategy that was initiated in 2012. The objective of
these targeted inspections was to evaluate current compliance with
combustible dust management requirements, and confirm that every sawmill
has an effective and sustainable plan for the management of wood dust. A
core team of 10 prevention officers conducted the inspections. In
total, 144 locations were inspected.

WorkSafeBC officers conducted these
inspections to monitor how effectively mills were meeting their
combustible dust management requirements. Under the Workers Compensation Act,
all employers have the legal responsibility to keep their worksites
safe from injury and disease. WorkSafeBC officers conduct inspections
to determine the extent to which employers are managing safety on their
worksites. Where prevention officers find issues that can cause an
unsafe environment for workers, officers will educate and consult, and
as necessary, write orders to oblige the employer to address those
safety issues; as required, WorkSafeBC may also apply administrative

Inspection results for the Combustible Dust
Initiative indicate that many sawmill operators have put significant
efforts into improving the management and control of combustible dust,
with a substantial number of employers found to be in compliance with
the Occupational Health and Safety Regulation. However, not all
employers were found to be currently achieving compliance.

Inspection results summary

  • 249 inspections were undertaken related to combustible dust regulations. 
  • 83 of the 144 locations inspected were in
    compliance at the time of inspection and received no orders related to
    combustible dust. Many of those locations had dust control plans
    incorporating significant engineering controls to augment and mitigate
    the amount of manual dust cleanup required.
  • 61 employers were issued a total of 93
    orders related to combustible dust. Most of these orders were for
    unacceptable levels of dust accumulations outside normal production
    areas; i.e. basements, crawl spaces, overhead areas, areas hidden behind
    motor control centres or cabinets, and outside areas.
  • 11 employers were issued a total of 13
    stop-work orders due to unacceptable accumulations of secondary dust and
    other significant violations, which posed an immediate hazard to the
    health and safety of workers. In most cases, the areas noted were
    cleaned the same day, allowing production to resume by the next shift.
    These locations are subject to frequent ongoing inspections to ensure
    compliance is maintained while mill operators address the challenges
  • Two locations inspected during the
    initiative received a second stop-work order and have been directed to
    participate in a closely monitored compliance plan that includes weekly
    submissions to WorkSafeBC prevention officers regarding their dust
    management process. Officers are inspecting these locations at an
    increased frequency during this monitored phase to ensure the workplaces
    remain in compliance with WorkSafeBC requirements and expectations.
  • WorkSafeBC officers will continue to
    inspect sawmills on a regular basis to ensure that employers continue to
    manage and safely remove combustible dust from their workplaces
  • 17 warning letters were recommended during
    this inspection phase to advise employers that an administrative penalty
    may be considered for further similar violations of the regulations and
    3 administrative penalties were recommended for violations of the
    regulations. Warning letters and penalties are tools used by officers,
    as necessary, to motivate certain employers to comply with the Workers Compensation Act
    and the Occupational Health and Safety Regulation. The application of
    either sanction process is dependent on several factors, including the
    level of risk related to combustible dust violations and the motivation
    required of the employer.

From the Globe and Mail:

Five damning quotes from new inspections of B.C. sawmills


B.C.’s workplace safety watchdog says a three-month inspection blitz shows the forest industry is getting better at cleaning up potentially hazardous sawdust, but only 83 of the 144 locations inspected were in compliance with regulations.

Safety inspectors conducted 249 inspections in the last three months targeting combustible dust – a campaign that began with two deadly sawmill explosions in 2012.

In a report released Tuesday, WorkSafeBC concluded “many sawmill operators have put significant efforts into improving the management and control of combustible dust.”

Yet 11 employers were issued a total of 13 stop-work orders during the three-month period “due to unacceptable accumulations of secondary dust and other significant violations, which posed an immediate hazard to the health and safety of workers.” In most cases, the areas were cleaned the same day, allowing production to resume by the next shift.

Although the report does not identify which companies failed to comply with safety standards, inspection reports obtained through a Freedom of Information request show that some of the province’s leading forest companies are among those now facing penalties for unsafe working conditions.

Here are some of the violations the inspectors found:

Sigurdson Forest Products Ltd., Williams Lake:
“The edger created a potential combustible dust cloud with an ignition hazard in the form of a bare, unprotected metal halide light bulb within the cloud. Dust accumulations were observed on interior building structure inside the sawmill where the product exited the edger.
“The mezzanine (roof over the mill lunch room) was observed with accumulations of combustible wood dust. The shavings bin conveyor belt and pulley drive was observed buried in secondary wood dust.”

Tolko Industries, Williams Lake:
“Primary and secondary combustible dust has collected in several areas at this employer’s location. The areas that require immediate attention [are] the chip screen area in the sawmill and blower room ceiling area in the planer building. The employer was directed to suspend production in the planer until the concentrations of combustible dust [are] safely removed from the blower room ceiling. The sawmill can operate if the combustible dust can be safely removed from the chip screen area.”

Weyerhaeuser Company, Princeton:
“Excessive levels of both primary and secondary accumulations of combustible dust were found throughout the debarker/cutoff saw building, sawmill operating floor and sawmill basement.
“Primary accumulations of combustible dust were found built-up and in contact with potential ignitions sources such as conveyor tailspool or roller bearings or the accumulations had been allowed to persist and spread to other areas.

“Secondary accumulations of combustible dust exceeding 1/8" were observed on beams, rafters, equipment, light fixtures, cable trays, electrical MCC units (on top and inside), field transformers, electrical motors & gear reducers, and wall [braces] throughout the mill. The secondary accumulations were in excess of five per cent of the overall surface area of the debarker/cut-off saw area, the sawmill operating floor, and the sawmill basement.”

Canfor Corp., Chetwynd:
“Several areas within the sawmill operating floor and basement were found to have combustible dust accumulations in excess of acceptable limits or were found in contact with potential ignition sources.
“Examples of inadequately maintained ventilation systems in the planer mill were noted that included bent and damaged piping, ill-fitting enclosures, duct tape at joints, compromised bonding connections.

“The employer has failed to ensure that regular and adequate inspections are made of process equipment or facilities to prevent the accumulation of combustible dusts.”

Western Forest Products Inc., Chemainus:
“When the unacceptable accumulations of secondary dust under this locations planer crawl space [were] observed, this employer did not hesitate in shutting down production and initiating clean up.
“Unacceptable accumulations of fine secondary combustible dust was observed accumulated in a semi enclosed crawl space under this locations planer. The dust was present up to 1/2 inch accumulations in cable trays, up to 2.5 to 3 inches in depth under the vibrating conveyor and over 1/8th of an inch in depth on horizontal surfaces including the fire system piping and on the top of an electrical transformer. It is apparent that this location has not been cleaned for several months.”

More Related to this Story

Sunday, March 2, 2014

OSHA Issues Guidance for Inspectors on Combustible Dust

From the National Law Review.

Occupational Safety and Health Administration (OSHA) Issues Guidance for Inspectors on Combustible Dust | The National Law Review

Occupational Safety and Health Administration (OSHA) Issues Guidance for Inspectors on Combustible Dust

OSHA inspectors must consider a manufacturer’s or importer’s use of
information gained from actual explosion events, lab testing, published
data on similar materials or particle size to assure they have properly
classified their products for combustible dust hazards under the revised
Hazard Communication Standard (HCS), OSHA said in a recent guidance

The agency’s HCS was revised to bring it into harmony with a global
standard. Since that standard does not contain a classification for
combustible dust hazards, OSHA amended the standard's definition of
“hazardous chemical” to include combustible dust so as to maintain
coverage of the hazard under its HCS.

That move has put the agency in conflict with industry stakeholders
who claim inclusion of combustible dust in the new rule amounts to
backdoor rulemaking. A lawsuit over the agency action is currently
playing out in federal appeals court.

Marc Freedman of the U.S. Chamber of Commerce said the memo
perpetuates problems OSHA created by including combustible dust in the
standard. He noted that the agency did not give stakeholders a full
opportunity to comment on its inclusion of combustible dust during the
HCS rulemaking. Freedman also complained that OSHA still does not have a
definition of combustible dust, yet employers are expected to identify
combustible dust hazards and train their employees about it.

“The way the memo reads, it is effectively implementing a non-OSHA,
consensus organization's definition without the benefit of rulemaking,
without a feasibility analysis, economic analysis or examination of its
effect on small business. That's not how it's supposed to be done,”
Freedman said.

In its memo, OSHA noted the HCS does not define combustible dust.
OSHA explained that this omission results from ongoing OSHA rulemaking
on the substance and efforts underway at the United Nations. Instead,
the agency has provided interim guidance, including a definition in a
national emphasis program (NEP). A number of voluntary consensus
standards, most notably from the National Fire Protection Association
(NFPA), also provide guidance, according to the agency.

The HCS requires manufacturers and importers, called “classifiers” in
the guidance memo, to “identify and consider the full range of
available scientific literature and other evidence concerning the
potential hazards” of their products in the form they are shipped and
which might stem from normal use and foreseeable emergencies. There is
no testing requirement.

Actual experience following a deflagration or dust explosion often
offers the best information about the product, OSHA said. In such cases,
the product should be classified as a combustible dust unless it can be
shown conditions surrounding the event are not expected to occur under
normal conditions of use or in foreseeable emergencies.

Absent that information, classifiers may rely upon reliable
laboratory test data. The memo cites ASTM methods as well as an OSHA
method found in its NEP. Another option is published test data, such as
that distributed by NFPA and public databases, such as one from Germany
called the “Gestis-Dust-EX” database. Data may be relied upon provided
it derives from a material substantially similar to the classifier’s
product, OSHA said. If laboratory data or positive published test data
for similar substances are available but not used by the classifier, the
inspector must ask why, according to the guidance.

Where no test data are available or testing is inconclusive, the
classification may be based on available particle size, the agency said.
If the material will burn and contains a sufficient concentration of
particles that would pass through No. 40 or No. 35 sieves to create a
fire or deflagration hazard, it should be classified as combustible

The guidance was not meant to be all-inclusive, since other reliable
methods may be available, according to the agency, encouraging its
inspectors to consult agency resources in those instances. OSHA also
pointed out that the guidance is not intended for downstream users.
Rather it must be applied when inspecting manufacturers and importers,
usually from referrals concerning inadequate or inappropriate labels or
safety data sheets. Companies must comply with most provisions of the
rule by June 2015.

Jackson Lewis P.C. © 2014

Saturday, March 1, 2014

Fact Sheet: 2011 Combustible Dust Related Incidents, NFIRS Analysis

From Combustible Dust Explosions and Fires-ATEX blog and our friend John Astad at combustible Dust Policy Institute 

Friday, April 12, 2013

Fact Sheet: 2011 Combustible Dust Related Incidents, NFIRS Analysis

Fact Sheet: 2011 Combustible Dust Related Incidents, NFIRS Analysis from Combustible Dust Policy Institute

A Combustible Dust Policy Institute (CDPI) preliminary analysis of 2011 National Fire Incident Reporting System (NFIRS) incident data provided by the National Fire Data Center of the U.S. Fire Administration indicated over 500 combustible dust related incidents in manufacturing facilities where dust was the item first ignited. Near misses include incidents that did not result in any harm to personnel, the facility, process, or product. Analysis did not include the grain sector or coal-fired energy plants.
Additionally, the CDPI analysis does not include many incidents that were not reported by fire departments to the National Fire Data Center. As a result there are many more combustible dust related incidents that cannot be evaluated in determining whether the incident was a near miss or not. 
Special thanks to the nation's Fire Departments, NFIC State Program Managers, and the National Fire Data Center at the U.S. Fire Administration in sharing this valuable Information.  

Casual Pathways Between Near Misses and Catastrophic Events 
Excellent article by Carsten Busch from Norway, highlighting Common Cause Hypothesis (CCH) which also pertains to near misses and catastrophic combustible dust related incidents. In the current OSHA ComDust rulemaking process and recently reintroduced proposed combustible dust bill H.R. 691, incidents resulting in property/content loss (30% NFIRS analysis) yet no casualties (approximately 95%) are considered near misses. Yet the casual pathways (ignition sources, dust management strategies, etc.) for the consequences of all combustible dust related incidents are all the same. 
The true definition of a "near miss" is an incident not resulting in any harm to personnel, the facility, process, or product. So why are near misses ignored in accounting for combustible dust related fire and explosion hazards in protection of the workplace in the OSHA ComDust rulemaking process and recently reintroduced proposed combustible dust bill H.R. 691?
Report on preliminary findings of a study of incident reporting systems for near misses in non­medical domains. This can also apply to combustible dust related incidents/accidents where NFIRS data provides a multitude of information in developing barriers for the prevention of future accidents.

Near Misses in Non­-medical Domains
"Consequently, the same patterns of causes of failure and their relations precede both adverse events and near misses." Sounds familiar with ComDust related incidents at facilities whether it was flash fire, dust explosion, or layer fire? They all have casual pathways of improperly managed ignition sources and fuel sources. A written fire prevention plan (FPP) addresses these casual pathways initially at the organizational level. The next step would be implementation at the technical and operational level.

"We defined a near miss as any event that could have had adverse consequences but did not and was indistinguishable from fully fledged adverse events in all but outcome." Note: National Fire Incident Reporting System (NFIRS) was not included in the report of near misses in non­medical domains. 

U.S. Chemical Safety Board (CSB): Near Misses.
Dust Explosion Hazard Awareness / Imperial Sugar Management and Workers
(Page 54 .pdf) "The CSB concluded that the small events and “near-misses” caused company management, and the managers and workers at both the Port Wentworth, Georgia, and Gramercy, Louisiana, facilities to lose sight of the ongoing and significant hazards posed by accumulated sugar dust in the packing buildings."

CSB Key Findings: Imperial Sugar Refinery
Page 48 .pdf)  # 4 "Company management and the managers and workers at both the Port Wentworth, Georgia, and Gramercy, Louisiana, refineries did not recognize the significant hazard posed by sugar dust, despite the continuing history of “near-misses’”

(Page 14 ,pdf) "Operators and mechanics reported being involved in multiple flash fires during their employment at the Gallatin facility. At the time of the incidents, many were aware that the iron dust could burn or smolder. However, they were not trained to understand the potentially severe hazard when accumulated dust is dispersed in air. Rarely would operators report the minor flash fires and “near-misses” that periodically occurred."

(page 27 .pdf) CSB Recommendations to Hoeganaes 2011-4-I-TN-R9
"Develop and implement a “near-miss” reporting and investigation policy that includes the following at a minimum:"
• Ensure facility-wide worker participation in reporting all near-miss events and operational disruptions (such as significant iron powder accumulations, smoldering fires, or unsafe conditions or practices) that could result in worker injury.

• Ensure that the near-miss reporting program requires prompt investigations, as appropriate, and that results are promptly circulated throughout the Hoeganaes Corp.

• Establish roles and responsibilities for the management, execution, and resolution of all recommendations from near-miss investigations

• Ensure the near-miss program is operational at all times (e.g. nights, weekends, holiday shifts).  

Near misses can no longer be ignored. It's very distressing that OSHA in the combustible dust rule
making process in conjunction with the legislators in the reintroduction of the proposed combustible dust bill H.R. 691 have chosen to ignore 95% of combustible dust related incidents in manufacturing facilities, which do not result in personnel casualties. Yet these very same incidents, as history illustrates are precursors to catastrophe.

Friday, February 28, 2014

What You Need to Know About ComDust

What You Need to Know About ComDust

From our friends at Wood Products – December 2012
What You Need to Know About ComDustby our friend Jamison Scott at Air Handling Systems

With the increase of combustible dust incidents, OSHA is visiting woodworking facilities with greater frequency

Combustible dust is a serious issue in the woodworking industry. Gaining national attention in 2008 when a major sugar refinery in Georgia exploded due to combustible dust, in 2012 alone, the woodworking industry saw a major sawmill in British Columbia, Canada, launch a fireball reportedly 60 meters high due to a suspected combustible dust explosion. Additionally a wood pellet maker in New Hampshire suffered a third combustible dust related incident.

While the occurrences and severity of combustible wood dust related fires have been increasing, the incidence of OSHA (Occupational Safety and Health Administration) inspections related to combustible dust in woodworking facilities has also increased dramatically.

Combustible Wood Dust Terms

Combustible dust, as defined by the National Fire Protection Assn. (NFPA), is “a finely divided combustible particulate solid that presents a flash hazard or explosion hazard when suspended in air or the process-specific oxidizing medium over a range of concentrations.” Another definition, by OSHA, describes combustible dust as fine particles that present an explosion hazard when suspended in air under certain conditions.

However, it is not simply defining a specific dust, it is determining its explosibility. Important factors include size, shape, moisture as well as environment.

The Kst value can be used to quantify the severity of a dust explosion. The higher the Kst value, the greater the explosion characteristic of the dust. For example, wood flour (wood dust) has a Kst Value of >200 and ≤ 300, meaning it has a strong explosion characteristic. The Hazard Communication Guidance for Combustible Dusts also lists a dust explosion class rating system from St 0 – St 3. The dust explosion class of wood flour is St 2.

NFPA defines the size of “Deflagrable Wood Dust” as being 500 microns (0.5mm, 0.0196 inch) or less and having a moisture content of less than 25 percent. Another way to measure, according to NFPA 664 (, is to see if the material will pass through U.S. No. 35 Standard Sieve, which is approximately the “size of fairly coarse sand.”

The word “wood” itself is defined by NFPA as “cellulosic material derived from trees, and other cellulosic materials including, but not limited to, wheat straw, flax, bagasse, coconut shells, corn stalks, hemp, rice hulls, and paper or other cellulosic fiber used as a substitute or additive to wood.” Additionally, the term “Wood-Derived Materials” is defined by NFPA as “sawdust, sander dust, planer shavings, hoggings, wood flour, and moulder waste.”

The Combustible Dust Explosion

In order to have a fire you must have “Fuel”, “Ignition” and “Oxygen,” the three main elements of the “Classic Fire Triangle.” For a combustible dust explosion, you must add “Dispersion” and “Confinement,” which together creates the “Dust Explosion Pentagon.” (See diagram page 34.)

With many larger combustible dust explosions there are two issues: the initial explosion and the secondary explosion, which typically comes from fugitive dust that becomes dispersed and suspended due to the disturbance caused by the initial explosion.

This is what happened at the Imperial Sugar explosion in 2008. The initial explosion occurred at one location within the facility and the explosion was so forceful that it literally shook other sections of the building, releasing and suspending the previously settled fugitive dust, thus creating dust clouds in enclosed rooms that exploded as fire spread throughout the building. There is suspicion this is also what happened at the sawmill explosion in British Columbia earlier this year.

Explosion and/or Inspection?

Under the right conditions a combustible dust explosion can occur. Under just about any condition OSHA can inspect a facility.

Combustible dust is on OSHA’s radar screen, and inspections have increased substantially as have the penalties. OSHA is taking this matter seriously, using the general duty clause in classifying combustible dust violations. One OSHA citation stated “layers of combustible wood dust were allowed to accumulate to depths over surface areas in quantities that exposed workers to fire and or explosion hazards.” The layers of wood dust in this citation were in direct violation of the current “housekeeping” regulation in that it accumulated on I-beams, inside the trough of ceiling joists as well as on the floor.

The citation also found “when combustible wood dust was cleared from surfaces, the employer used cleaning methods that increased the potential for a combustible dust deflagration and or explosion” because “the employer use 30 psi compressed air to blow down and clear combustible wood dust.” This citation specifically refers to NFPA 664 (2012) which states “surfaces shall be cleaned in a manner that minimizes the generation of dust clouds…only a low gauge pressure 15 psi…shall be used.”

Steps Toward Prevention

Studying past combustible dust explosions, OSHA citations, as well as NFPA standards provide guidelines for prevention. A few areas that should be highlighted include: Hazard Recognition/Assessment; Building Design & Engineering Controls; Administrative Controls; Housekeeping; and Worker Training.

• Hazard Recognition/Assessment includes determining if dust is combustible via Dust Explosion Testing, which may include Particle Size and Moisture Analysis, Explosion Severity Test which will tests the Kst value, and Minimum Explosible Concentration (MEC) — all as mentioned earlier. Hazard Recognition/Assessment also covers issues related to NFPA as well as the potential application of State and Local codes.

• Building Design & Engineering Controls cover “fixed structures that are built into a facility or processing equipment designed to remove or minimize a hazard.” Building Design focuses on the prevention of fugitive dust accumulation on surfaces, beams, etc., and all invisible areas such as hung or suspended ceilings. This is where good housekeeping is imperative. Engineering controls focus on the equipment such as dust collection systems or prevention devices such as spark detection in dust collectors, ductwork and explosion venting and suppression.

• OSHA requires detailed documentation, which is one of the most important roles in Administrative Controls. In addition to documentation, various NFPA Standards have detailed proper methods of operating procedures, inspections, testing and maintenance procedures, as well as training.

• One of the most important things any facility can do is fully engage in housekeeping and fugitive dust control. If underlying surface colors are not readily discernible there could be a dust deflagration hazard as mentioned in NFPA documents.

If you can see the dust, do not ignore it. Clean it up, but do not blow off with an air gun as that simply releases and stratifies the dust — use a vacuum to collect dust. Then investigate to determine the source. For example, if the ductwork is not airtight, seal joints. When inspecting the workplace for dust accumulations again consider all flat surfaces including rectangular shaped ductwork, overhead beams, flat surfaced lighting fixtures, and all invisible areas such hung or suspended ceilings.

So while a combustible dust explosion might occur, the likelihood of an OSHA inspection is much greater. OSHA’s role is to protect the worker. And with the increase of combustible dust incidents, OSHA is visiting woodworking facilities with greater frequency. Proper understanding of the enormous destruction of a combustible dust fire, with the knowledge that an explosion can be mitigated by ensuring the proper steps are implemented, will protect the workforce, facility as well as the industry.

Jamison Scott is executive vice president and is a third generation member of family-owned industrial ventilation manufacturing firm Air Handling Systems in Woodbridge, CT. With over 20 years of experience, he serves on the Technical Advisory Board for Air Pollution Control and Chairs the Industrial Dust Task Force for the Wood Machinery Manufacturers of America. He holds an MBA and is a licensed sheet metal contractor in the state of Connecticut. For information contact: 203-389-9595;; To keep current on combustible dust related issues visit:

NFPA Standards

NFPA is the National Fire Protection Assn., an International Codes and Standards Organization that creates voluntary consensus standards used by various groups including AHJ (Authority Having Jurisdiction), which can be anyone from a building inspector to a fire marshal. There are several useful standards covering combustible dust published by NPFA. Some of the most relevant are:

• NFPA 61: Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities. Current Edition: 2013

• NFPA 484: Standard for Combustible Metals, Current Edition: 2012

• NFPA 654: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids, Current Edition: 2013

• NFPA 655: Standard for Prevention of Sulfur Fires and Explosions, Current Edition: 2012

• NFPA 664: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities, Current Edition: 2012

• And the newly proposed - NFPA 652: Standard on Combustible Dusts. Released this fall is the first draft of the proposed NFPA 652 Standard on Combustible Dusts. This new standard will be a companion to the related standards. The goal of the new standard, as proposed in the preliminary draft, “is to provide safety measures to prevent and mitigate fires and dust explosions in facilities that handle combustible particulate solids.” The development of this standard will take approximately three years, with a proposed release date of fall 2015.

Fire Prevention Tips for Wood Pellet Plants.

From our friends at| Harrington Group, Inc.

Fire Prevention Tips for Wood Pellet Plants

Posted on Thursday, January 16th, 2014
My last blog discussed the dangers of wood pellet plant facilities and included an overview of several recent incidents. Today, I would like to review a few fire prevention tips for wood pellet plants. The process of manufacturing wood pellets involves all the right ingredients for explosions and fires to occur with a concerning frequency the potential to cause serious injuries, damage to property, and interruption of production.

The amount of wood, dust, various ignition sources inherent in the wood pellet production process presents a high risk of explosion and fire. However, there are strategies that can be implemented to reduce the risk of fire and explosions and to mitigate the impact should they occur:
  • Conduct a Risk Assessment – professionals, like fire protection engineers, are well-versed at identifying risks for various facility types. A risk assessment will include a physical survey of the facility or designated area to identify and quantify various explosion and fire threats to life, property, and business operations. The assessment will identify and quantify various defenses against those threats. The results of the assessment will be carefully analyzed and any significant weaknesses in the explosion and fire defenses will be identified. Specific solutions to correct these weaknesses are then developed and are optimized for cost and function. The building owners, tenant, and stakeholders should be involved in the process of optimizing solutions so that their specific objectives are understood and satisfied.
  • Combustible Dust Considerations – many times, incidents at wood pellet production facilities involve combustible dust, as seen in the examples described above. A few strategies to help mitigate combustible dust exposure include:
    • 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; and
    • 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.
  • Overall Construction Standards – According to Rob Cruickshank of the RSA Group, “using non-combustible construction materials and composite panel insulation are first choices when it comes to wood and biomass pellet production plants.”  He further advises that composite panels should have a minimum fire resistance of two hours, and be made with mineral wool rather than expanded foam plastic insulation. Walls separating fuel storage facilities from the rest of the plant should be concrete and provide at least two hours of fire separation.
As the wood pellet production industry continues to grow, so does the importance to facility owners of developing strategies to minimize the exposure to fire and explosion risks. Steps should be taken to design explosion and fire safety into these facilities, as well as implementing safe operation and effective maintenance processes. An experienced fire protection engineer with credentials in combustible dust risks is a great partner to help you develop the appropriate explosion and fire protection design and prevention strategies needed to help mitigate the exposure of your employees, facilities, and the surrounding communities to these risks.

By , CEO and Founder of Harrington Group, Inc.