Safely handling flammable and combustible liquids

Fire prevention is especially important where flammable and combustible liquids are used. Make sure your employees understand how to identify, handle, and store flammable and combustible liquids.

Flammable liquids ignite easily and burn quickly, and have flashpoints below 100º F. Examples include gasoline, acetone, or methanol.

The flash point is the temperature at which a liquid produces enough vapors to be ignited. More than any other factor, flash point determines the flammability hazard of a liquid; the lower the flash point, the more flammable the material. Flammable liquids are known as “Class I” liquids.

There are three classes of flammable liquids:

• Class IA liquids have flashpoints below 73º F and boiling points below 100º F.
• Class IB liquids have flashpoints below 73º F and boiling points at or above 100º F.
• Class IC liquids have flashpoints at or above 73º F and below 100º F.

A combustible liquid has a flash point at or above 100º F up to 200º F. Examples include diesel fuel and motor oil. Combustible liquids are divided into three classes:

• Class II liquids have flashpoints at or above 100º F and below 140º F.
• Class IIIA liquids have flashpoints at or above 140º F and below 200º F.
• Class IIIB liquids have flashpoints at or above 200º F.
   

Use and storage

Do not use flammable and combustible liquids where there are any open flames, sparks, or other sources of ignition (smoking, welding, etc.).

To avoid dangerous sparks caused by static electricity, containers of flammable liquids must be properly grounded and bonded while dispensing the liquid.

Storage must be in approved containers (drums, safety cans, etc.). Containers must be closed when not in use. The regulation at 1910.106 describes permissible storage containers by size and material (glass, plastic, metal, etc.) for various categories of liquids.

OSHA has special requirements for lighting and other electrical wiring used in flammable liquid storage rooms. Containers may also be kept in approved storage cabinets. OSHA sets limits on how much flammable or combustible liquid can be stored in one area.

Fire extinguishers must be available where flammable and combustible liquids are stored. Always observe “no smoking” signs where these liquids are present. Employers may be required to post a “no smoking” sign even if the company prohibits smoking on the premises.