Fire control is the practice of reducing the heat output of a

fire Fire is the rapid oxidation of a fuel in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. Flames, the most visible portion of the fire, are produced in the combustion re ...

, reducing the area over which the fire exists, or suppressing or extinguishing the fire by depriving it of

fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work (physics), work. The concept was originally applied solely to those materials capable of releasing chem ...

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

, or

heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

(see

fire triangle The fire triangle or combustion triangle is a simple model for understanding the necessary ingredients for most fires. The triangle illustrates the three elements a fire needs to ignite: heat, fuel, and an oxidizing agent (usually oxygen). A fir ...

Fire prevention Fire prevention is a function of many fire departments. The goal of fire prevention is to educate the public on the precautions that should be taken to prevent potentially harmful fires from occurring. It is a proactive method of preventing fir ...

and control is the prevention, detection, and extinguishment of fires, including such secondary activities as research into the causes of fire, education of the public about fire hazards, and the maintenance and improvement of fire-fighting equipment.

Types of fires and extinguishers

In some territories, such as the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, fire types are categorised with letter codes. Each class is a specific type of fire that requires a specific control method based on its cause. Understanding the cause is essential so that the correct fire extinguisher is used; if the wrong extinguisher is used, it can either make the fire worse or fail to control it.

Flammable solids: Class A (US/EU/AU)

A fire that is fuelled by ordinary combustible solids, like paper, wood, or plastics is one of the most common and simplest types to extinguish with a

fire extinguisher A fire extinguisher is a handheld active fire protection device usually filled with a dry or wet chemical used to extinguish or control small fires, often in emergencies. It is not intended for use on an out-of-control fire, such as one which ha ...

. The most common method to control them is to remove heat by spraying the burning solid fuels with

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

. Another control method for most class types of fires would be to reduce the oxygen content in the immediate vicinity of the fire (i.e., "smother" the fire), by, simply, covering it with the natural ground

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

mud Mud (, or Middle Dutch) is loam, silt or clay mixed with water. Mud is usually formed after rainfall or near water sources. Ancient mud deposits hardened over geological time to form sedimentary rock such as shale or mudstone (generally cal ...

. A

fire blanket A fire blanket is a safety device designed to extinguish incipient (starting) fires. It consists of a sheet of a Fire-retardant material, fire retardant material that is placed over a fire in order to smother it. Small fire blankets, such as fo ...

consists of a sheet of a fire retardant material that is placed over most class types of fires in order to smother them.

Sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda (or simply “bicarb” especially in the UK) is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cat ...

dry powder is another commonly sourceable method to smother most class types of fires in effective fire control. Another method to smother the fire is the introduction of an inert gas such as

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

. Another common type of extinguisher uses the chemical

monoammonium phosphate Ammonium dihydrogen phosphate (ADP), also known as monoammonium phosphate (MAP) is a chemical compound with the chemical formula (NH4)(H2PO4). ADP is a major ingredient of agricultural fertilizers and dry chemical fire extinguishers. It also has ...

. In a

wildfire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a ...

, fire control includes various

wildland fire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts depend on many factors such as the available fuel, the local atmospheric conditions, the features of the terrain, and the size of the wildfir ...

techniques such as defensible space, widening the

fuel ladder A fuel ladder or ladder fuel 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.firebreak A firebreak or double track (also called a fire line, fuel break, fireroad and firetrail in Australia) 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 firebre ...

s and backfires to minimize the brush fire reaching new combustible fuel and spreading further.

Flammable liquids: Class B (US/EU/AU), and flammable gases: Class B (US) / Class C (EU/AU)

Many flammable liquid and gas based fires (hydrocarbons,

petroleum Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...

, and similar fuels) cannot be efficiently controlled with water because fuels with a density less than water (such as

gasoline Gasoline ( North American English) or petrol ( Commonwealth English) is a petrochemical product characterized as a transparent, yellowish, and flammable liquid normally used as a fuel for spark-ignited internal combustion engines. When for ...

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

) float on top, resulting in the fire continuing to burn. In addition, the heat of an intense fire may cause water to flash into steam in an explosion which can spread the flaming fuel more widely. The configuration of some fuels, such as

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

and baled waste paper, may 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. Class B fires should be extinguished with foam, powder, or carbon dioxide extinguishers. Some Class-B fires can be controlled with the application of chemical fire suppressants. Applying 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.

Combustible metals: Class D (US/EU/AU)

Fires based on combustible or

pyrophoric A substance is pyrophoric (from , , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolithium compounds and triethylb ...

metals can include those involving potassium, uranium, sodium, lithium, calcium, and plutonium. The most common are those fuelled by magnesium and titanium. The recommended method to extinguish them is to use a dry powder fire extinguisher, which smothers the fire while absorbing heat.

Electrical fires: Class C (US) / Class E (AU) / Unclassified (EU)

Fires involving

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

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, possibly resulting in

electrical shock An electrical injury (electric injury) or electrical shock (electric shock) is damage sustained to the skin or internal organs on direct contact with an electric current. The injury depends on the density of the current, tissue resistance and ...

. They can be effectively controlled by removing the oxygen with a dry powder (typically

and

sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda (or simply “bicarb” especially in the UK) is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cat ...

) or carbon dioxide, dry chemical ABC extinguisher. The source of electricity also needs to be removed to eliminate re-ignition. Once the electricity is removed, the remaining fire can be dealt with as one of the other classes.

Grease fires (cooking): Class F (EU/AU) / Class K (US)

Fires involving cooking fats and oils (grease fires) are a distinct cagetory, set apart from other flammable solids and liduids. Water should not be used on such a fire, as it will disperse the material and cause the fire to grow rapidly. The correct type of fire extinguisher is usually a wet chemical fire extinguisher.

Ventilation

Fires can spread through the interior of a structure as the hot

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

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. Ventilation is important when it comes to the fire service, since it is "the systematic removal or heat, smoke and fire gases from a structure". The main purpose for ventilating a fire is to decrease the likelihood of a

flashover A flashover is the near-simultaneous ignition of most of the directly exposed combustible material in an enclosed area. When certain organic materials are heated, they undergo thermal decomposition and release flammable gases. Flashover occurs wh ...

from occurring. The best time to ventilate is before sending anyone into a structure so that the path the fire will take is through the roof and not through the front door when firefighters open it, allowing more oxygen to feed the fire.

References

{{Authority control Firefighting Wildfire suppression