11/07/2008

Powder Poof! Dust in the Workplace Can Combust

Disasters don't always start with chemicals. Even something as sweet as sugar
can explode.

The Oregon branch of the U.S. Occupational Safety and Health Administration
(OSHA) has issued an alert to warn industries of the dangers of combustible
dust. Injuries and fatalities have occurred in the state of Oregon because of a
wood-dust fireball, dust flash from powder-coating filters, and a grain-dust
explosion.

Assessing the risk
The Industrial Fire Hazards Handbook from the National Fire Protection
Association states that "any industrial process that reduces a combustible
material and some normally noncombustible materials to a finely divided state
presents a potential for a serious fire or explosion." Industries that are
potentially at risk include those that manufacture or handle food (such as
candy, starch, flour or feed), plastics, wood, rubber, furniture, textiles,
pesticides, pharmaceuticals, dyes, coal, metals (such as aluminum, chromium,
iron, magnesium, and zinc), and industrial plants that generate fossil-fuel
power.

Any "material that will burn in air" in a solid form can be explosive when in a
finely divided form. It is possible for different dusts of the same chemical
material to have different ignition and explosive characteristics. These depend
on particle size, shape, moisture content, and other variables. If you are not
sure whether or not a product produces combustible dust, one possible source of
information is the Material Safety Data Sheet (MSDS) for the product, however
OSHA recommends checking with the chemical manufacturer for additional
information.

For a dust fire to occur, three elements must be present: combustion dust
(fuel), an ignition source (heat), and oxygen in the air (oxidizer). When two
other elements are added to the mix - dispersion of dust particles in
sufficient quantity and concentration, and confinement of the dust cloud - an
explosion will occur.

OSHA recommends that facilities assess their potential for dust explosions by
looking at the following:


  • Materials that can be combustible when finely divided;
  • Processes that use, consume or produce combustible dusts;
  • Open areas where combustible dusts may build up;
  • Means by which dust may be dispersed in the air; and
  • Potential ignition sources.

Employees must be trained in safe work practices specific to dust control and
ignition source control, which apply to their job tasks and to the entire
plant. Canadian employers should review their relevant legislation and ensure
the workplace is in compliance.

more info


AplusA-online.de - Source: U.S. American Department of Labor Occupational Safety & Health Administration