Preventing and extinguishing a fire involves eliminating one of the three factors presented in the fire triangle: fuel, oxidizer, and heat. For a combustion reaction and a fire to occur, three factors are needed: fuel, oxidizer, and chain reaction.
Fuel is any material that can be oxidized. They can be solid (paper, wood, cotton), liquid (alcohol, gasoline, ether, fuel oil), or gaseous (hydrogen gas, acetylene, LPG (Liquefied Petroleum Gas)).
Among liquid fuels, we have volatiles, which releases vapors at room temperatures, such as alcohol, gasoline, and ether; and there are also non-volatile ones, which practically do not release vapors, such as paint, fuel oil, grease, among others. Volatiles pose a more significant risk.
The oxidizer is oxygen gas (O 2), which comes into contact with the fuel and reacts. Combustion needs to occur, and this can be seen through a simple and well-known experiment: if we place a glass over a lighted candle, the flame will go out with time, as all the oxygen has been consumed and the reaction ceases.
3- Chain Reaction
Heat provides the energy needed for the reaction to continue. For example, the grass is fuel, and it is in contact with oxygen in the air. Still, for its burning to occur, an ignition or activation energy is needed, which is provided, for example, by a spark, as when someone throws a lit cigarette. Then combustion begins, releasing heat that provides the minimum energy needed for the chain reaction to continue.
So, to fight a fire, we have to remove one of these factors. See how:
One of the main ways to fight a fire by fire clean up crew is through cooling, lowering the temperature. This method is ideal for class A fires, which occur with solid fuels that burn at the surface and its depth, leaving residues (ashes).
To eliminate heat, use extinguishers appropriate for each type of fire. But it is necessary to know precisely which extinguisher to use for each type of fire; otherwise, it can make the situation worse. For example, let’s say the fire is taking place in electrical equipment that poses a shock hazard (class C fire), in which case a water extinguisher would not be indicated. Still, a dry chemical extinguisher would be indicated.
2-Eliminating The Fuel
This is done by removing the material from the site. For example, let’s say a hydrogen gas inlet is open; we can then close it, taking out the fuel that is being burned.