OSHA standard 29 CFR 1920.106 addresses the handling, storage, and use of flammable and combustible liquids. Flammable and combustible liquids are, in short, liquids that can burn. They are classified or grouped as either flammable or combustible by their flashpoints.
The flash point of the liquid is the temperature at which it gives off vapor sufficient to form an ignitable mixture with the air near the surface of the liquid or within the vessel used as determined by appropriate test procedure and apparatus.
When vapors of a flammable liquid are mixed with air in the proper proportions in the presence of a source of ignition, rapid combustion or an explosion can occur. The flammable range includes all concentrations of flammable vapor or gas in air, in which a flash will occur or a flame will travel if the mixture is ignited.
There is a minimum concentration of vapor or gas in air below which propagation of flame does not occur on contact with a source of ignition. There is also a maximum proportion of vapor in air above which propagation of flame does not occur. These boundary-line mixtures of vapor with air are known as the lower and upper flammable limits (LFL or UFL), respectively, and they are usually expressed in terms of percentage by volume of vapor in the air.
The primary hazards associated with flammable and combustible liquids are fire and explosion. Flammable and combustible liquids are present in almost every workplace. Fuels and many common products like solvents, thinners, cleaners, adhesives, paints, waxes, and polishes may be flammable or combustible liquids. Everyone who works with these liquids must be aware of their hazards and how to work safely with them.
Spray mists of flammable and combustible liquids in the air may burn at any temperature if an ignition source is present. The vapors of flammable and combustible liquids are usually invisible. They can also be hard to detect unless special instruments are used.
Most flammable and combustible liquids flow easily. A small spill can cover a large area of workbench or floor. Burning liquids can flow under doors, down stairs, and even into nearby buildings. Materials like wood, cardboard, and cloth can easily absorb flammable and combustible liquids. Even after a spill has been cleaned up, a dangerous amount of liquid could still remain in surrounding materials or clothing, giving off hazardous vapors.
A good plan for the safe use of flammable and combustible liquids contains these components:
Be sure to take adequate precautions when handling flammable and combustible liquids to prevent the ignition of flammable vapors. Some sources of ignition include:
Proper storage and handling of flammable and combustible liquids will help prevent fires from occurring; only approved, closed containers for storage of flammable or combustible liquids may be used under OSHA rules. Such containers include safety cans or containers approved by the U.S. Department of Transportation.
A safety can is a container that has a self-closing lid, internal-pressure relief, and flame arrestor with a capacity of not more than 5 gallons. Inexpensive, plastic cans are not approved for use in roofing operations. However, manufacturers do sell plastic containers that meet the OSHA requirements for safety cans.
Flammable liquids that are extremely viscous, or difficult to pour, like single-ply adhesive, can be left in their original shipping containers. Similarly, OSHA allows the use of original containers of flammable liquids that are in quantities of one gallon or less.
Safety cabinets allow for greater quantities of flammable and combustible liquids to be stored safely inside buildings. Up to 60 gallons of a flammable liquid or as much as 120 gallons of a combustible liquid may be stored indoors in a safety cabinet. Each cabinet must be labeled "Flammable-Keep Fire Away." Up to three cabinets may be stored in one room. Without a safety cabinet, only 25 gallons of either flammable or combustible liquids are allowed to be stored inside a building.
Static electricity may be generated when transferring liquids, gases, or solids through pipes or hoses. It is important to dissipate this electric charge when handling flammable and combustible materials. When transferring flammable or combustible liquids from one container to another, the two containers must be "bonded" together. The bonding process involves attaching a wire with alligator clips on each end to both containers. The clips must penetrate the container coating and touch metal. You may need to score the paint with the alligator clips.
To dissipate static electricity, the container receiving the liquid must be in contact with the ground and not insulated from contact with the ground. For example, plastic or composite pickup truck bed liners prevent the flow of static electricity to ground because the liner does not conduct electricity. The receptacle container must have a clear path to ground, by direct contact or use of a grounding strap or wire, to effectively eliminate static.
Well-designed and maintained ventilation systems remove flammable vapors from the workplace and reduce the risk of fire and health problems. The amount and type of ventilation needed to minimize the hazards of flammable and combustible liquid vapors depend on such things as the kind of job, the kind and amount of materials used, and the size and layout of the work area.
An assessment of the specific ways flammable and combustible liquids are stored, handled, used, and disposed of is the best way to find out if existing ventilation controls (and other hazard control methods) are adequate.
Skin and eye contact should be avoided when working near flammable or combustible liquids. To make sure injury to eyes and skin does not occur, wear safety glasses with side shields, laboratory coats (coveralls are acceptable in shop settings), and closed-toe shoes. This is only minimum protection and must be upgraded if necessary.
Additional Personal Protective Equipment (PPE) such as chemical goggles, face shields, chemical aprons, and chemical resistant gloves and respiratory protection must be worn if there is a chance of exposure to flammable or combustible liquids above OSHA's Permissible Exposure Limit (PEL). The PEL is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise.
An emergency eyewash and safety shower should be located in all areas where flammable or combustible liquids are used. If there is skin or eye contact, then flush the affected area for at least 15 minutes and report to your employer for evaluation and treatment.
Even if employees take all the necessary precautions to protect themselves from hazardous material spills, they still need to be ready to handle emergencies safely. In emergencies like chemical fires and spills, act fast.
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