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Fire control is the practice of reducing the heat output of a fire, reducing the area over which the fire exists, or suppressing or extinguishing the fire by it of fuel, oxygen, or heat (see fire triangle).
The classification below relates to the United States of America: different classifications exist in other countries.
The most common method to control a class-A fire is to remove heat by spraying the burning solid fuels with water. Another would be to reduce the oxygen content of the atmosphere near the (i.e., "smother") the fire, perhaps by introducing such an inert gas as carbon dioxide.
In a Wildfire, fire control includes such wildland fire suppression techniques as defensible space, opening the fuel ladder spacing, and removing fuel in the fire's path with firebreaks and backfires.
Some Class-B fires (hydrocarbons, petroleums, and fuels on fire) cannot be efficiently controlled with water because its specific gravity exceeds theirs, and they therefore burn atop it. Applying a combination of fire suppressant foam and water is a common and effective method for blanketing the fuel and thereby blocking oxygen. The configuration of such fuels as coal and baled waste paper result in a deep, burrowing fire, that is less easily controlled by applying water to the surfaces of the fuel.
Applying chemical fire suppressants can control some class-B fires.
Electricity continuously ignites the fuels of Class C fires and relates to such electrical equipment as plastic cable jackets. The application of water is sometimes ineffective, and a general concern about conductivity and personnel safety exists. Removing oxygen can effectively control Class C fires, and removing electricity eliminates re-ignition.
Fires can spread through the interior of a structure as the hot gases spread due to the expansion of the gases as a result of the combustion. Some fires can be partially controlled by venting these gases to the outside through manufactured heat vents in the structure's roof, or by the fire department cutting holes in the roof.