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Food Products Make Up a Growing Percentage of Combustible Dust Incidents

Posted on April 26, 2019

Food products were involved in 43% of global combustible dust incidents last year, according to the 2018 Combustible Dust Incident Report by DustEx Research. This percentage is a significant gain from 2017, when food products were involved in only 32% of incidents.

Wood products were the second most common materials, involved in 28% of incidents. This is a small decrease from 2017, though the report noted that fires and explosions involving wood products tended to be larger and more expensive.

In the United States and Canada, 2018 saw a total of 175 fires, 40 explosions, 40 injuries, and one fatality. Thirteen of the incidents caused facility damage of more than $1 million. In three of those, the damage totaled more than $20 million.

Companies across industries that haven’t yet taken steps to identify and mitigate their combustible dust risk will soon be working against the clock. The 2019 version of NFPA 652: Standard on the Fundamentals of Combustible Dust establishes September 7, 2020, as the deadline for completing a dust hazard analysis (DHA) for existing facilities and processes. The DHA must be repeated every five years and every time a process changes.

Quick facts about combustible dust hazards and incident prevention

What dusts are combustible?

Combustible dusts are found across industries. Almost every organic material can become a combustible dust, which is why the food industry is responsible for such a high percentage of incidents. Food products involved in incidents in 2018 included grain, flour, barley, pecan, cocoa, spices, cereals, and milk powder. Sawdust, wood chips, lumber, and insulation were the main culprits in wood processing plants.

What conditions lead to combustible dust incidents?

Combustible dust itself is not avoidable, but devastating fires and explosions are. Combustible dust incidents occur when dusts have been allowed to accumulate.

A typical combustible dust incident proceeds in two stages:

  • A primary explosion occurs in processing equipment or in an area where fugitive dust has accumulated.
  • The primary explosion causes other dust — such as dust that has accumulated on overhead surfaces — to disperse into the air. When this dust is ignited, it causes a secondary explosion that tends to be much more destructive than the first.

That’s why OSHA’s Combustible Dust National Emphasis Program (NEP) specifies that dust should not be allowed to accumulate above 1/32 of an inch over more than 5% of floor area of any given room. In facilities larger than 20,000 ft2, dust accumulation should not exceed 1,000 ft2.

One key thing to note about these calculations is that “floor area” doesn’t just mean the area beneath your feet. OSHA specifies that accumulations on overhead beams, joists, dusts, the tops of equipment, and other surfaces — including vertical surfaces if dust adheres to them — should also be included. When inspectors visit your facility, they will collect samples from roof beams, the tops of pipes and ductwork, within ductwork, and more.

What OSHA standards apply to combustible dust?

OSHA does not have a combustible dust standard, but the National Emphasis Program references several standards, including the following:

  • 1910.22 Housekeeping
  • 1910.307 Hazardous Locations
  • 1910.1200 Hazard Communication
  • 1910.269 Electric Power Generation, Transmission and Distribution (coal handling)
  • 1910.272 Grain Handling Facilities
  • General Duty Clause, Section 5(a)(1) of the Occupational Safety and Health Act (employers must keep workplaces free from recognized hazards likely to cause death or serious physical harm)

While it’s tempting to focus on the specific standards, arguably the last one on the list is the most important. It means that OSHA can issue a citation anytime employers aren’t keeping their employees safe from recognized hazards. Here are a few examples of General Duty Clause citations OSHA has issued under the Combustible Dust NEP:

  • Equipment such as grinders, shakers, mixers and ductwork were not maintained to minimize escape of dust into the surrounding work area. Employer did not prevent the escape of dust from the packaging equipment, creating a dust cloud in the work area.
  • Interior surfaces where dust accumulations could occur were not designed or constructed to facilitate cleaning and to minimize combustible dust accumulations. Regular cleaning frequencies were not established for walls, floors, and horizontal surfaces such as ducts, pipes, hoods, ledges, beams, etc.
  • Compressed air was periodically used to clean up the combustible dust accumulation in the presence of ignition sources.

There are several aspects to combustible dust control. But they all boil down to preventing hazardous levels of dust from accumulating. Check out our top 6 vacuum solutions for combustible dust applications to find equipment that can help you keep your facility safe.