The Underrated Hazard of Combustible Dust

It’s hard to imagine that dust can explode. Unfortunately, it does—and with catastrophic consequences, depending on the type of dust involved and the circumstances.

In 1878, for instance, the Washburn A. Mill in Minneapolis was obliterated in an instant, killing 14 workers on the spot, destroying five other mills, and instantly reducing the city’s milling capacity by a full third. The cause? A spark had ignited the thick flour dust trapped inside the mill. Many other dust explosions have occurred since then, most of them coal-dust explosions in underground coal mines. From 1980 to 2005 alone, the U.S. Chemical Safety and Hazard Investigation Board (CSB) recorded 119 worker fatalities, 718 worker injuries, and substantial damage to many industrial facilities.

As those who have taken OSHA training probably know, a dust explosion needs five ingredients to happen:
1.    Combustible dust (surprisingly, including normally harmless materials such as flour and sugar)
2.    Dispersion or suspension at a high concentration
3.    Oxidant (typically, oxygen, but can also be other gases)
4.    Confined space
5.    Ignition source (usually a naked flame or electrical discharge, but can also be a hot surface, such as an overheated bearing)

When all five are present, the suspended dust cloud will rapidly combust and cause an explosion.

Such is the danger of dust explosions—and the inadequate attention given to it by some quarters across a number of industries, including mining, plastics, wood, and paper, as well as the less obvious ones such as food and grain—that the Occupational Safety and Health Administration (OSHA), the work safety watchdog of the U.S. Department of Labor, is especially vigilant about infractions of OSHA guidelines concerning combustible-dust accumulation.

OSHA refers interested parties and stakeholders who want to know more about combustible dust to www.osha.gov/dsg/combustibledust/index.html.

Recently, OSHA found Carmen Creative Cabinets LLC in violation of several safety and health provisions, including those involving hazards associated with combustible-dust buildup. Following an inspection of the company’s manufacturing facility in Belton, Texas, OSHA has recommended penalties totaling $64,800.

Carmen Creative Cabinets employs some 30 workers and, in accordance with OSHA SOP in the case of violators, was given 15 business days to contest the findings, to ask for a conference with the OSHA area office, or to accept the findings and comply with the proposed penalties. An independent OSHA review commission will be convened in case the company decides to contest the findings.

Perkins pointed out that the proposed penalties were not just for discovered combustible-dust accumulation hazards but also for other safety and health violations. Specifically, OSHA reported the company’s failures to:
1.    Train and certify its forklift operators
2.    Install approved electrical equipment
3.    Put in place the correct conduit for compressed air
4.    Carry out what’s called a “hazard communication program and training” on proper handling and use of different chemicals
5.    Implement safety measures for nail guns
6.    Provide unobstructed access to circuit-breaker boxes and fire extinguishers

Included in the health violations reported by OSHA were the company’s failures to: supply its workforce with the mandatory personal protective equipment, keep its restroom facilities clean, and have available to its employees first-aid supplies.