When we first heard about the terrible explosion at the International Nutrition animal feed plant in Omaha, Nebraska that claimed two lives and injured many others this week, we had one thought: Combustible dust.
In non-technical terms, combustible dust is any dust from industrial processes that will catch fire and have the potential for explosions in confined spaces. Wikipedia offers this simple explanation of conditions:
There are four necessary conditions for a dust explosion or deflagration:
1. A combustible dust
2. The dust is suspended in the air at a high concentration
3. There is an oxidant (typically atmospheric oxygen)
4. There is an ignition source
There are many sources of ignition – fire, friction, arc flash, hot surfaces and electrostatic discharge. It’s an exposure in many industries: food production, metal processing, wood products chemical, manufacturing, rubber & plastics, coal-fired power plants, to name a few.
OSHA Investigates
Yesterday, Celeste Monforton of The Pump Handle reported that “OSHA and other investigators suspect that an explosion of combustible dust played some role in the disaster.” Her post recounts the OSHA and the Obama administration’s failure to take action on passing a combustible dust standard.
“But month after month, year after year, the Labor Department has failed to act. Last fall, OSHA indicated it plans to take comments in April 2014 from a select group of small business on a draft version of a regulation. That’s a step the agency previously suggested would take place in April 2011, then December 2011, then October 2013, and November 2013.”
Monforton also points to an excellent Center for Public Integrity (CPI) investigation that analyzed data compiled by the federal Occupational Safety and Health Administration and the U.S. Chemical Safety Board, finding that more than 450 accidents involving dust have killed nearly 130 workers and injured another 800-plus, Since 1980, noting that “Both agencies, citing spotty reporting requirements, say these numbers are likely significant understatements.” Here’s the full report: Unchecked dust explosions kill, injure hundreds of workers
In the wake of the Imperial Sugar disaster which killed 14 workers and injured 36, the Chemical Safety Board has produced many reports on combustible dust explosions, including the excellent safety video below.
We also found this short video by FM Global to be compelling.
The text explantion for the video says:
“Did you know that dust can explode?
That is to say any organic material–wood, paper, rubber, fiber, food, tobacco, etc.–can create dust given the right conditions.
In this controlled demonstration at FM Global’s one–of-a-kind Research Campus in West Glocester, RI, the five ingredients needed to cause dust to explode–air, fuel, heat, suspension and confinement–are provided to cause the explosion, or more appropriately, a partial volume deflagration.
Here, one hard hat full (11 lbs. or 5 kg.) of coal dust is placed in a trough approximately 2/3 of the height of the enclosure, which measures 10 ft. wide x 12 ft. deep x 15 ft. high. A small charge was then introduced to disturb and suspend the dust followed by an ignition source (bottle rocket).
Although you may not be able to totally eliminate combustible dust from your process or your facility, there are prevention measures you can take to reduce the frequency of dust fires and explosions. Likewise, control measures can reduce the severity of a fire or explosion. Together, these can help you reduce the likelihood of property damage and business interruption.
Takeaway: If it didn’t start out as a rock, it can explode.”
Find out more about this test in an article Dust to Ashes (PDF) in FM Global’s Reason, page 38.
Tags: combustible dust, explosions, fires, OSHA