Fire control consists of depriving a
fireFire is the rapid oxidation of a combustible material releasing heat, light, and various reaction products such as carbon dioxide and water. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the...
of
fuelFuel is any material that is burned or altered to obtain energy and to heat or to move object. Fuel releases its energy either through a chemical reaction means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion...
,
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
or
heatIn physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body....
(see
fire triangleThe fire triangle or combustion triangle is a simple model, from the practitioners of firefighting, for understanding the ingredients necessary for most fires. It has largely been replaced in the industry by the fire tetrahedron, which add further aspects, but still does not explain fire fighting...
) to prevent it from spreading or to put it out entirely.
The standard and most common way to control a class-A fire (the combustion of a flammable material with oxygen and heat) is to remove heat by spraying the burning solid fuels with
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
from a fire-hose connected to a pump. Other methods of controlling a class-A fire would be to "smother" the fire with carbon dioxide, such as from a
fire extinguisherA fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user , or otherwise requires the expertise of a fire...
, cutting off its oxygen.
Fire control consists of depriving a
fireFire is the rapid oxidation of a combustible material releasing heat, light, and various reaction products such as carbon dioxide and water. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the...
of
fuelFuel is any material that is burned or altered to obtain energy and to heat or to move object. Fuel releases its energy either through a chemical reaction means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion...
,
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
or
heatIn physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body....
(see
fire triangleThe fire triangle or combustion triangle is a simple model, from the practitioners of firefighting, for understanding the ingredients necessary for most fires. It has largely been replaced in the industry by the fire tetrahedron, which add further aspects, but still does not explain fire fighting...
) to prevent it from spreading or to put it out entirely.
Class-A fires
The standard and most common way to control a class-A fire (the combustion of a flammable material with oxygen and heat) is to remove heat by spraying the burning solid fuels with
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
from a fire-hose connected to a pump. Other methods of controlling a class-A fire would be to "smother" the fire with carbon dioxide, such as from a
fire extinguisherA fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user , or otherwise requires the expertise of a fire...
, cutting off its oxygen. In a
wildfireA wildfire is any uncontrolled fire that occurs in the countryside or a wilderness area. Reflecting the type of vegetation or fuel, other names such as brush fire, bushfire, forest fire, grass fire, hill fire, peat fire, vegetation fire, and wildland fire may be used to describe the same phenomenon...
, fire control would include various
suppressionWildfire 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 removing fuel in the fire's path and digging trenches, thereby preventing the fire from gaining new fuel and spreading.
Class-B fires
Class-B fires (hydrocarbons and fuels on fire) require much different handling than the standard water approach. Many fuels, such as
gasolineGasoline or petrol is a petroleum-derived liquid mixture, primarily used as fuel in internal combustion engines...
or
oilAn oil is any substance that is liquid at ambient temperatures and is hydrophobic but soluble in organic solvents. Oils have a high carbon and hydrogen content and are nonpolar substances. The general definition above includes compound classes with otherwise unrelated chemical structures,...
float on water, and water would actually end up spreading the fire further. Other fuels, such as
coalCoal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
, will not be put out by water, as fire spreads to the inside of the coal and cannot be reached by water—as soon as the water stops, the fire inside of the coal spreads back out to the outside. Fire control of these fires requires specialized methods, and can be problematic to ordinary fire stations because these materials may not always be available.
One way to control a class-B fire would be to dump chemical dust on it—this is also a method for handling class-A fires, and actually tends to be preferable because sprayed water tends to cause property damage. Gasoline fires are more often smothered in a cooling
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
foamThe most general definition of foam is a substance that is formed by trapping many gas bubbles in a liquid or solid. It can also refer to anything that is analogous to such a phenomenon, such as quantum foam. Often the term is used in reference to polyurethane foam , XPS foam, Polystyrene, or many...
.
Class-C fires
Class-C fires are electrical fires—fires that are caused by an electrical source and get their heat from electricity. These fires are dangerous because if water is used on them, electrical current will be passed through the stream and back into the firefighter. There are only two ways to deal with this type of fire—take away the oxygen (smother it with foam or a fire extinguisher) or simply turn off the electricity, which will cause the fire to either die out or become a regular class-A fire.
Ventilation
Most fires spread as hot
gasThis page is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas .A gas is one of four states of matter. Near absolute zero, a substance exists as a solid...
es move through the structure. Some fires can be controlled or limited by venting these gases to the outside either horizontally through
windowA window is a transparent opening in a wall that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material...
s and doors or vertically through existing openings or by cutting holes in the structure's roof. This can aggravate a fire if it introduces new oxygen, or permits a draft past fuel or structure, making professional training in how to perform ventilation required to do it safely—a
backdraftA backdraft is a situation which can occur when a fire is starved of oxygen; consequently combustion ceases but the fuel gases and smoke remain at high temperature. If oxygen is re-introduced to the fire, eg...
(the rapid combustion of a room, nearly akin to an explosion) may result if done incorrectly, or at the very least cause the fire to spread further.
See also
- Ballistic System for Fighting Forest Fire
- Fire classes
In firefighting, fires are identified according to one or more fire classes. Each class designates the fuel involved in the fire, and thus the most appropriate extinguishing agent. The classifications allow selection of extinguishing agents along lines of effectiveness at putting the type of fire...
- Fire sand bucket
A fire sand bucket or fire bucket is a steel bucket filled with sand which is used to put out fires. Typically, fire buckets are painted bright red and have the word 'Fire' stencilled on them in white lettering. They are placed in prominent positions in rooms or corridors. They are a basic,...