Flammable Liquids

Flammable liquids are those whose vapors can ignite, even at below room temperature, when an ignition source is applied. The liquid “vaporizes”, and the vapors, rather than the liquid itself, can ignite.

The degree of flammability of a liquid depends on several factors. The flash point is the lowest temperature at which the liquid will give off enough flammable vapors to ignite if an ignition source is present. In general, the lower the flashpoint, the more flammable the liquid.

Vapor density and flammable range are also important. Vapor density is a measure of a vapor’s weight when compared to air. Vapors that are heavier than air (greater than 1) can sink to the ground, gather and travel long distances across the floor to sources of ignition, such as pilot lights from water heaters. Flammable range, described in terms of lower flammable limit (LFL) and upper flammable limit (UFL), is the range of vapor-to-air concentration over which it will ignite. In general, the higher the vapor density and wider the flammable range, the more flammable the liquid.

National Fire Protection Association (NFPA) 30, Flammable and Combustible Liquid Code, provides classification of various flammable liquids, including their degree of flammability.

Flammable liquid fires or explosions often occur in the workplace setting, such as a plant or chemical distribution facility, where flammable liquids are mixed, stored or otherwise handled. Companies handling flammable liquids should have a comprehensive flammable liquid safety program to prevent fires from occurring.

Flammable liquid fires can also occur in the home. For instance, Passen Law Group has represented a man who was seriously burned when the vapors of a concrete sealant he was applying to his basement floor ignited and caused a flash fire and explosion.


Gasoline burn injuries occur most frequently in the workplace among mechanics, power equipment operators and others who use gasoline as part of their work. Gasoline-related injuries are also associated with certain summer recreation activities, such as boating, camping and barbeque grilling.

In 2010, there were over 2,000 residential fires in which natural gas was ignited and over 1,000 in which LP-Gas was ignited. The fires resulted in several hundred injuries and 77 deaths, according to the National Fire Protection Association.

Vapor Flash Fires

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