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7.1: Removing Elements

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    66921

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    Removal of Heat

    Removal of heat, or cooling of the fire is effective by stopping the heat feedback loop, causing the fuel to stop being vaporized, or pyrolyzed. As a result, removal of heat is effective on solid and liquid fueled fires. Removal of heat is the most common method of extinguishment utilized by structural firefighters.

    Firefighters spray water on the roof of a burning structure
    Figure \(\PageIndex{1}\): Cooling of the fire.
    Copyright:"house fire spray" by Rob Swystun is licensed under CC BY 2.0.

    Removal of Fuel

    Removal of fuel separates the fuel from the oxygen and heat needed to complete the oxidation reaction. This can be by creating a barrier between the fuel and the oxygen, or simply shutting off the fuel supply such as turning off a burner on the stove. Another example can be seen below where wildland firefighters construct a fire line, or an area without fuel that prevents the fire from being able to continue burning.

    wildland firefighters construct a fire line
    Figure \(\PageIndex{2}\): Wildland firefighters constructing a fire line.
    Copyright: "Wildland firefighters for the Gila District" by BLMArizona. Public Domain.

    Removal of Oxygen

    Removal of the oxygen from the reaction also works by separating the fuel and the oxygen. In some cases, this is done concurrently with removal of fuel, for example when applying a foam blanket, or smothering a fire with sand. Oxygen can also be removed from the fire by introducing a heavier gas such as argon or carbon dioxide to displace the oxygen from the fire environment.

    Caution sign indicating potential presence of carbon dioxide gas; advises immediate evacuation if alarm sounds.

    Figure \(\PageIndex{3}\): Carbon dioxide presence.

    Inhibiting the Chemical Chain Reaction

    The final method of extinguishment is by attacking the chemical chain reaction itself, rather than removing a component of the reaction.

    Chain reactions usually consist of many repeating elementary steps, each of which has a chain carrier. Once started, chain reactions continue until the reactants are exhausted. Fire and explosions are some of the phenomena associated with chain reactions. The chain carriers are some intermediates that appear in the repeating elementary steps. These are usually free radicals.1

    Agents extinguish fire through inhibition stop or slow the free radicals' activity so they cannot continue to repeat the chain reaction or work as an intermediary between the reacting elements.

    This page titled 7.1: Removing Elements was last modified on Fri, 21 Aug 2026 02:07:53 GMT and is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Robert Smith.