Fire control
Encyclopedia
control of fire
'control of fire' is the practice of reducing the heat output of a fire, or reducing the area over which the fire exists, or suppressing or extinguishing the fire by depriving a fire
of fuel
, oxygen
or heat
(see fire triangle
).
The classification below relates to the United States of America. Different classifications exist in other countries.
. Another method of controlling a class-A fire would be to reduce the oxygen content of the atmosphere in the immediate vicinity of the (i.e., "smother" the fire), such as by the introduction of an inert gas such as carbon dioxide
.
In a Wildfire
, fire control includes various wildland fire suppression
techniques such as defensible space
, opening the fuel ladder
spacing, removing fuel in the fire's path with firebreak
s and backfires, to minimize the brushfire from reaching new combustible fuel and spreading further.
s, and fuels on fire) cannot be efficiently controlled with water. Fuels with a specific gravity less than water, such as gasoline
or oil
, float on water, resulting in the fire continuing in the fuel on top of the water. The application of a combination of fire suppressant foam mixed with water is a common and effective method of forming a blanket on top of the liquid fuel which eliminates the oxygen needed for combustion.The configuration of some fuels, such as coal
and baled waste paper, result in a deep seated and burrowing fire, resulting in less effective fire control by the application of water on the outer surfaces of the fuel.
Some class-B fires can be controlled with the application of chemical fire suppressants.
as a continuous power source for the ignition of the fuels associated with electrical equipment, such as plastic cable jackets. The application of water does not always result in effective fire control, and there is a general concern regarding conductivity and personnel safety. Class C fires can be effectively controlled by removing the oxygen. The removal of electricity as a continuous ignition source is important to eliminate re-ignition. Once the electricity is removed, the result is a Class A fire.
es 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.
'control of fire' is the practice of reducing the heat output of a fire, or reducing the area over which the fire exists, or suppressing or extinguishing the fire by depriving a fire
Fire
Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....
of fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
, oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
or heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
(see fire triangle
Fire triangle
The fire triangle or combustion triangle is a simple model for understanding the ingredients necessary for most fires.The triangle illustrates a fire requires three elements: heat, fuel, and an oxidizing agent . The fire is prevented or extinguished by removing any one of them...
).
The classification below relates to the United States of America. Different classifications exist in other countries.
Class-A fires
The most common method to control a class-A fire is to remove heat by spraying the burning solid fuels with waterWater
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
. Another method of controlling a class-A fire would be to reduce the oxygen content of the atmosphere in the immediate vicinity of the (i.e., "smother" the fire), such as by the introduction of an inert gas such as carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
.
In a Wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
, fire control includes various wildland fire suppression
Wildland fire suppression
Wildfire suppression refers to the firefighting tactics used to suppress wildfires. Firefighting efforts in wildland areas requires different techniques, equipment, and training from the more familiar structure fire fighting found in populated areas...
techniques such as defensible space
Defensible space (fire control)
In the context of fire control, Defensible Space is the natural and landscaped area around a structure that has been maintained and designed to reduce fire danger, sometimes called Firescaping. "Defensible space" is also used in the context of wildfires, especially in the wildland-urban interface...
, opening the fuel ladder
Fuel ladder
A fuel ladder is a firefighting term for live or dead vegetation that allows a fire to climb up from the landscape or forest floor into the tree canopy. Common fuel ladders include tall grasses, shrubs, and tree branches, both living and dead...
spacing, removing fuel in the fire's path with firebreak
Firebreak
A firebreak is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebreak may occur naturally where there is a lack of vegetation or "fuel", such as a river, lake or canyon...
s and backfires, to minimize the brushfire from reaching new combustible fuel and spreading further.
Class-B fires
Some Class-B fires (hydrocarbons, petroleumPetroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
s, and fuels on fire) cannot be efficiently controlled with water. Fuels with a specific gravity less than water, such as gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...
or oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
, float on water, resulting in the fire continuing in the fuel on top of the water. The application of a combination of fire suppressant foam mixed with water is a common and effective method of forming a blanket on top of the liquid fuel which eliminates the oxygen needed for combustion.The configuration of some fuels, such as coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
and baled waste paper, result in a deep seated and burrowing fire, resulting in less effective fire control by the application of water on the outer surfaces of the fuel.
Some class-B fires can be controlled with the application of chemical fire suppressants.
Class-C fires
Class-C fires involve electricityElectricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
as a continuous power source for the ignition of the fuels associated with electrical equipment, such as plastic cable jackets. The application of water does not always result in effective fire control, and there is a general concern regarding conductivity and personnel safety. Class C fires can be effectively controlled by removing the oxygen. The removal of electricity as a continuous ignition source is important to eliminate re-ignition. Once the electricity is removed, the result is a Class A fire.
Ventilation
Fires can spread through the interior of a structure as the hot gasGas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
es 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.