OSHA to Issue Rule on Combustible Dust Hazards
May 22, 2009 // Published as a news service by IHS
The U.S. Department of Labor Occupational Safety and Health Administration (OSHA) will issue an advanced notice of proposed rulemaking to evaluate possible regulatory methods and request data and comments on issues related to combustible dust such as hazard recognition, assessment, communication, defining combustible dust and other concerns.
According to OSHA's Safety and Health Topics Combustible Dust web site, any combustible material and some materials normally considered noncombustible can burn "rapidly" when in a finely divided form. If such a dust is suspended in air in the right concentration, it can become explosive.
Combustible dusts are solids finely ground into fine particles, fibers, chips, chunks or flakes that can cause a fire or explosion when suspended in air under certain conditions, according to OSHA. Types of dusts include metal (aluminum and magnesium), wood, plastic or rubber, coal, flour, sugar and paper, among others.
According to a safety and health information bulletin published March 2008 by OSHA - "Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions" - three basic elements are needed for dust to explode:
- Combustible dust (fuel).
- Ignition source (heat).
- Oxygen in air (oxidizer).
Additional elements needed for a combustible dust explosion include:
- Dispersion of dust particles in sufficient quantity and concentration.
- Confinement of the dust cloud.
An initial (primary) explosion in processing equipment or in an area were fugitive dust has accumulated may shake loose more accumulated dust or damage a containment system such as a duct, vessel or collector, according to the bulletin.
As a result, if ignited, the additional dust dispersed into the air may cause one or more secondary explosions. These can be more destructive than a primary explosion due to the increased quantity and concentration of dispersed combustible dust.
In 2006, the U.S. Chemical Safety Board (CSB) recommended that OSHA issue a combustible dust standard.
OSHA received additional support for a combustible dust standard from the CSB during a congressional hearing in 2008 when the board said a new standard, combined with enforcement and education, could save workers' lives.
Since 1980, more than 130 workers were killed and more than 780 injured in combustible dust explosions, according to OSHA. These include 14 people who were killed in a dust explosion Feb. 7, 2008 at an Imperial Sugar Co. plant in Georgia and three workers who were burned in April 2009 in an Illinois pet food plant dust explosion.
More information about combustible dust is available from OSHA.
Source: U.S. Department of Labor Occupational Safety and Health Administration (OSHA).