How to work safely with flammable and combustible liquids

You may work with them in your home or in your workplace: gasoline, turpentine,
diesel fuel, paint and acetone. These are just a few examples of liquids that
are flammable or combustible, meaning they can catch fire or ignite easily.

A liquid is determined to be flammable or combustible based on its flashpoint
(the lowest temperature at which it ignites). Flammable liquids ignite at lower
temperatures than combustible liquids. Under the Workplace Hazardous Materials
Information System (WHMIS), flammable liquids have a flashpoint below 37.8C
(100F). Combustible liquids have a flashpoint at or above 37.8C (100F) and
below 93.3C (200F).


The most obvious hazard of a flammable or combustible liquid is the danger of a
fire or explosion. At temperatures above their flashpoints, flammable and
combustible liquids give off enough vapour to form mixtures with air that can
be easily ignited and burn. The ignition source can be a spark, a flame,
friction, a hot surface or any other source of ignition. "Hidden" sources
include static electricity, light switches and other electrical devices like
power tools. If sprayed or misted in air, flammable and combustible liquids may
burn at any temperature if there is an ignition source. Once ignited, flammable
and combustible liquids can spread fire widely by flowing easily under doors,
down stairs and even into neighbouring buildings.

The vapours formed by flammable liquids are usually invisible and hard to
detect without using special instruments. Flammable and combustible liquids can
be absorbed into materials like wood, cardboard and cloth and continue to
giving off hazardous vapours even after a spill appears to have been cleaned up.

In addition to the danger of a fire, there may be other hazardous properties of
flammable or combustible liquids. Some flammable and combustible liquids can
cause health problems, such as skin or eye irritation, or acute toxicity, and
some are corrosive to the skin. Many undergo dangerous chemical reactions if
they contact incompatible chemicals such as oxidizing materials, or if they are
stored improperly.

Most workplaces use some type of flammable and combustible liquid in the form
of fuels and many other common products like solvents, thinners, cleaners,
adhesives, paints, waxes and polishes. Everyone who works with these liquids
must be aware of their hazards and how to work safely with them.

Basic safety tips

  • - READ AND UNDERSTAND the Material Safety Data Sheet (MSDS) for information about the hazards and necessary precautions for working safely with all the materials you are using.

  • - PREVENT the release of flammable vapours and mists into the workplace air to minimize the risk of a fire or explosion.

  • - USE only in well-ventilated areas.

  • - KEEP containers closed when not in use.

  • - BE AWARE of any health hazards associated with the flammable and combustible liquid and follow recommended safe handling procedures.

  • - STORE flammable and combustible liquids away from incompatible materials (e.g., oxidizers).

  • - USE the smallest amount of flammable liquid necessary in the work area.

  • - CLEAN up spills immediately. Use approved containers for disposal of rags and other work materials.

  • - USE non-sparking ventilation systems and equipment. Eliminate ignition sources (sparks, smoking, flames, hot surfaces) when working with or handling flammable and combustible liquids.

  • - GROUND all metal drums, transfer vessels, hoses and piping to prevent buildup of static charge. Ground clips must contact bare metal.

  • - USE only containers and dispensing equipment (faucet, pump, drip can) that are approved for use with flammable liquids.

  • - PRACTICE good housekeeping by keeping areas clear of materials that can burn.

  • - REPORT leaks, spills and ventilation failures to your supervisor immediately.

  • - UNDERSTAND and PRACTICE emergency procedures so that you know what to do if it becomes necessary.

  • - DO NOT HEAT containers or distribution systems containing flammable or combustible liquids.

  • - DO NOT USE flammable or combustible liquids for anything other than their intended uses.

Further Information - Source: Canadian Centre for Occupational Health and Safety