Tag Archives: combustion

Combustible Dust: Understanding How To Prevent Industrial Fire Hazards

Many manufacturing and mining industries create large amounts of Combustible Dust that have the potential of becoming highly explosive and causing fatalities and millions of dollars in damage.

More than 450 accidents involving combustible dust have killed nearly 130 workers and injured another 800-plus since 1980, according to a Center for Public Integrity analysis of data compiled by the federal Occupational Safety and Health Administration and the U.S. Chemical Safety Board. These fires and explosions have been caused by a variety of dust sources including sugar, nylon fiber, coal, iron, plastic and wood. Most in the manufacturing industry are aware of some of the dangers and have read or seen reports of these explosions in the news.

An explosion ripped through the New Cumberland A.L. Solutions titanium plant in West Virginia on December 9, 2010, fatally injuring three workers. The plant workers were processing titanium powder at the time of the explosion. The AL Solutions incident is one of nine serious combustible dust incidents investigated by the CSB since 2003, including the Imperial Sugar disaster near Savannah, Georgia, in 2008 as well as three combustible dust incidents over a six month period in 2011 at the Hoeganaes facility located in Gallatin, TN. These nine explosions and fires caused a total of 36 deaths and 128 injuries.

Dust and other debris will always be present in the manufacturing process. Since dust is inevitable in the process, manufacturing facilities must take the proper measures to understand the risks, learn as much as possible about the threat and take solid measures to prevent potential hazards and be prepared should an incident take place.

What is Combustible Dust?

The technical definitions for combustible dust will differ depending on the source that you reference. The Occupational Safety and Health Administration (OSHA) in the United States defines combustible dust as “a solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition, which presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations”. In Canada, one example is Alberta’s Occupational Health and Safety Code which defines combustible dust as “a dust that can create an explosive atmosphere when it is suspended in the air in ignitable concentrations”.

What are examples of materials that can be a combustible dust hazard?

Believe it or not the Occupational Safety and Health Administration (OSHA) lists over 120 materials as combustible dust makers. See the chart below for a full list:

What Industries Are at Risk for Combustible Dust?

OSHA notes some of the industries at risk include:

  • Agriculture
  • Food
  • Pharmaceutical
  • Pesticide
  • Rubber
  • Plastic
  • Woodworking
  • Textiles
  • Chemical
  • Recycling
  • Coal fired Power Plants

Causes of a Combustible Dust Explosion

There are three elements needed for a dust fire to
occur and is referred to as the “Fire Triangle”. They are:

  • Combustible dust (i.e. the fuel)
  • Oxygen
  • Heat source


There are also two additional elements needed to cause a combustible dust explosion, often called the “Dust Explosion Pentagon”

  • Dispersion of dust particle in sufficient quantity
  • Confinement of the dust cloud


Secondary Explosions

After the initial combustible dust explosion, there is often a secondary explosion caused. The second explosion is caused by dust that is shaken loose from the primary explosion which also ignites. The secondary explosion may be actually larger and more severe than the initial explosion.

Conditions Needed for a Dust Explosion to Occur

The simple recipe for a dust explosion to happen is for combustible dust particles to be suspended in air and include an ignition source. In reality, several other conditions generally need to be present

  • The combustible dust must release enough heat to sustain the fire.
  • The dust must be suspended in air.
  • The dust must have a particle size large enough to spread the flame.
  • The concentration of the dust suspension must be within the explosive range.
  • An ignition source must be in contact with the suspended dust.
  • Adequate oxygen must be present to support and sustain combustion

Dust Hazard Assessment for Your Facility

Plants should carefully look at the following areas to determine the potential for dust explosions:

  • Materials
  • Processes
  • Open Areas of dust
  • Hidden Areas of dust
  • Dust dispersion sources
  • Ignition sources

Preventative Measures

  • Develop a housekeeping plan
  • Use only approved vacuum cleaners for dust collection
  • Find and eliminate hidden areas where dust accumulates
  • If possible, avoid or minimize horizontal surface where dust may accumulate
  • Use cleaning methods that do not generate dust clouds
  • Use proper electrical and ventilation systems


  • Develop and implement a combustible dust inspection and control program including when inspections will take place and specific actions to control dust.
  • Develop a hot work permit system for activities such as welding and cutting.
  • Develop an ignition control program to eliminate or reduce sources of ignition. Keep ignition sources away from dusty areas or use suitable controls.
  • Educate and train employees regarding the hazards of combustible dusts and their role in eliminating the threat of explosions
  • Inspect for dust at regular intervals.
  • Regularly inspect machines, ducts, and ventilation systems for dust.

How to Select an Anti Static Explosion Proof Vacuum Cleaner

HafcoVac explosion proof vacuum cleaners are safe for use as part of a combustible dust control program and are suitable for many flammable and combustible materials. With no motors to arc and no moving parts to create friction or spark, our non-electric explosion proof vacuums are a safe, reliable and cost-effective solution for your business.

HafcoVac explosion proof vacuum cleaners bond all components of the vacuum together, ensuring no part is left isolated from its path to ground. When used in conjunction How to Select an Anti Static Explosion Proof Vacuum Cleaner with our MSHA approved static conductive hose, a HafcoVac explosion proof vacuum is an economical alternative to other products which often sell for many times the cost.

With performance uncompromised by explosion-proof vacuum safeguards, an upgrade to an explosion-proof vacuum cleaner will perform with the same power HafcoVac is known for. Best of all, you don’t have to sacrifice your budget to protect your business and employees.

If you are unsure if dust ignition proof vacuum equipment is necessary for your application or facility, a HafcoVac representative will gladly provide a thorough application analysis to ensure appropriate product selection.

Intrinsic Safety

HafcoVac explosion-proof industrial vacuums are suitable for use in Class I, Class II, and Class III environments, Division 1 and 2. Our explosion-proof pneumatic vacuums:

  • contains no moving parts, eliminating the possibility of ignition from mechanical friction or contact.
  • uses no electricity, eliminating sparks from motor arcing, shorts, switches, etc.
  • are fully grounded when an explosion-proof vacuum unit configuration is ordered, ensuring dangerous static electricity will not accumulate.

Intrinsic Safety is a protection technique for equipment operating in explosive environments. The principle states that electrical and thermal energy must not build up sufficiently to discharge. With heat or friction risks such as those present when using an electrically operated industrial vacuum safely eliminated, static electricity remains.

The complete grounding of all components, including air supply line, vacuum generating head, collection drum, dolly and vacuum hose ensure that static electricity is continuously dissipated, protecting against dangerous static buildup, which could lead to electrostatic discharge (ESD), posing potentially serious consequences when in the presence of combustible substances. HafcoVac explosion-proof vacuum models factory equipped as an explosion-proof configuration ensures static electricity will not accumulate.

It is critically important that the operator understands the functions of the grounding system. Inspections are suggested prior to each use to ensure the integrity of all grounding wires and points. Care must be taken to not circumvent any grounding safeguards, and should also be exercised to ensure parts such as hoses aren’t used interchangeably with those from non-explosion proof systems.

Are HafcoVac’s Vacuums Certified Explosion Proof?

Stainless Vac

To this date, there are no published certification procedures for air-powered (pneumatic) equipment.

HafcoVac anti-static grounded units (“x” model designation) machines meet the criteria for intrinsically safe operation – no moving parts, non-electric & fully grounded means the unit will not spark and will not generate dangerous amounts of heat.

Additionally, we have designed these machines specifically for use in hazardous locations – building in a double safeguard of conductive static dissipative materials & connections, coupled with complete grounding of all components of the unit.

An independent testing lab has stated that our “X” line can be used in hazardous locations, specifically in Class I, Class II, & Class III environments, divisions 1&2.

HafcoVac explosion proof vacuum cleaners are suitable for a wide range of applications. Safeguard your business from worker injury, OSHA fines or catastrophic incident by protecting your facility with HafcoVac’s safe non-electric anti-static vacuum cleaners.

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OSHA and NFPA Standards HafcoVac Vacuums Help You Comply With

OSHA Standards
NFPA Standards
1910.22: General Requirements: Housekeeping NFPA 61: Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities NFPA 485: Standard for the Storage, Handling, Processing, and Use of Lithium Metal
1910.38: Emergency Action Plans NFPA 68: Guide for Venting of Deflagrations NFPA 495: Explosive Materials Code
1910.94: Ventilation NFPA 69: Standard on Explosion Prevention Systems NFPA 499: Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas
1910.107: Spray Finishing Using Flammable and Combustible Materials NFPA 70: National Electrical Code® NFPA 505: Fire Safety Standard for Powered Industrial Trucks Including Type Designations, Areas of Use, Conversions, Maintenance, and Operation
1910.146: Permit-Required Confined Spaces (references combustible dust) NFPA 91: Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Solids NFPA 560: Standard for the Storage, Handling, and Use of Ethylene Oxide for Sterilization and Fumigat
1910.178: Powered Industrial Trucks NFPA 120: Standard for Fire Prevention and Control in Metal/Nonmetal Mining and Metal Mineral Processing Facilities NFPA 654: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids
1910.269: Electric Power Generation, Transmission and Distribution (coal handling) NFPA 432: Code for the Storage of Organic Peroxide Formulations NFPA 655: Standard for Prevention of Sulfur Fires and Explosions
1910.272: Grain Handling Facilities NFPA 480: Standard for the Storage, Handling, and Processing of Magnesium Solids and Powders NFPA 664: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities
1910.307: Hazardous (classified) Locations (for electric equipment) NFPA 481: Standard for the Production, Processing, Handling, and Storage of Titanium NFPA 1124: Code for the Manufacture, Transportation, Storage, and Retail Sales of Fireworks and Pyrotechnic Articles
1910.1200: Hazard Communication NFPA 482: Standard for the Production, Processing, Handling, and Storage of Zirconium NFPA 1125: Code for the Manufacture of Model Rocket and High Power Rocket Motors
NFPA 484: Standard for Combustible Metals, Metal Powders, and Metal Dusts

HafcoVac is providing information on pertinent OSHA and NFPA standards as a convenience to our customers. Our reference to OSHA, NFPA, MSHA or other governing bodies is not intended to be construed as an endorsement of this, or any specific product, by the respective agency.


Combustible Dust Decimates Chinese Tech Factory

Fires burn after combustible dust explosion in Chengdu, China

Aftermath of the Chengdu dust explosion. Photo: intomobile.com

Explosive Dust Kills Three in China

An explosion at a factory in the Chinese city of Chengdu has killed three workers and injured almost 20 others. This catastrophic explosion on May 20th, 2011 has been attributed to combustible dust accumulations, according to initial examinations by local authorities. The dust explosion led to the partial shutdown of the plant. Officials in Chengdu said the explosion had been caused by combustible dust in an air duct at a polishing workshop. Foxconn, a division of the Hon Hai Group of Taiwan, is the operator of the facility and occupies a golden position as one of Apple’s largest suppliers. The Chengdu facility appears to be a new factory and Foxconn boasts of hiring almost 100,000 new employees.

Warning Signs of a Dust Hazards

The Hong Kong-based labor watch-dog group called ‘Students and Scholars against Corporate Misbehavior’ had noted a problem with potentially combustible dust accumulations throughout the factory in a report on working conditions issued only 2 months ago. The group said workers at the Chengdu factory had complained this year that the ventilation of the polishing department to be wholly inadequate. Workers in this section of the factory are charged with polishing iPad cases and the polishing process produces copious amounts of explosive dust on a particulate scale near microscopic. Workers are forced to inhale this explosive dust even though they are wearing respirators. The particulate is so fine that when workers take off their cotton gloves, their hands are completely coated with this combustible dust. After the release of these findings, Foxconn issued a response; stating that it was unfortunate that S. A.C.O.M. was seeking to capitalize on insignificant findings.

Workers from the Foxconn plant show just how much explosive dust accumulates on their person during an average shift
Video by S.A.C.O.M., courtesy of Youtube.com


Corporate Damage Control

Apple issued a statement after the explosion, saying that they regretted the tragic accident and that the cause of the blast was under investigation. Foxconn has recently been expanding its operational reach all across China to keep up with production demands. Apple has a deep relationship with Foxconn; which has had to cope with several recent worker suicides. Labor rights groups believe the suicides were the result of harsh working conditions. Foxconn, however, insists employees are respected and are treated well. After the suicides, Foxconn took steps to mitigate internal stresses; hiring counselors and even installing nets on some buildings to prevent suicide attempts. Apple has praised Foxconn, saying the company has definitely saved lives.  Apple; which has an established and well documented code of conduct for international suppliers, audits plants annually, but has had to deal with continuing problems that propagate in China’s industrial sector.

Unforeseen Consequences of Combustible Dust Explosions

The subsequent shutdown has stirred fears of production/ supply interruptions for the latest iPad. IHS iSuppli, said that the explosion at the Chengdu facility “could result in the loss of production of 500,000 Apple iPad 2 tablet computers during the second quarter of this year.” IHS iSuppli said that while most of the iPad production was actually being completed in the city of Shenzhen, the concern is that the Shenzhen factory might not be able to compensate for the disruption in Chengdu.

The Necessity for Combustible Dust Mitigation Practices

The Chengdu incident brings to light the need for adequate combustible dust training procedures and effective housekeeping measures; such as employing dust cleaners, in order to eliminate the possibility of catastrophic combustible dust explosions in every sector of the manufacturing industry. HafcoVac Explosion Proof vacuums are compressed air powered and completely anti-static. No electricity means no possibility of ignition by proxy and can provide peace of mind for manufacturers and factory operators who truly care for the health, safety and well-being of their employees.