Powder Poof! Dust in the Workplace Can Combust

07/11/2008

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.

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