Breaking the Fire Triangle
Reducing heat on wildfires may be accomplished in two ways: cooling with water, foam, dirt, or scattering the available fuels to reduce the effect of radiant heat. Water or dirt should be directly applied on the fuels being consumed to reduce fuel temperature. Flames are actually the burning gases liberated by the heated fuels.
Water, dirt, foam and retardants will reduce the supply of oxygen for the combustion process. With water, use a fog nozzle. Fog performs a smothering function on the flaming gases by occupying air space with millions of finely divided particles of water. This smothering action can also be accomplished with chemical retardants dropped from fixed wing aircraft, helicopters or applied from the ground. Foam will also reduce the supply of oxygen and smother the fire.
Foam is more effective than water alone. It smothers the fire by completely coating the fuel with water in the form of foam. Very little runs off. Instead, it stays on the surface of the fuel until it is evaporated (which it does very slowly). During this time it protects the fuel from the heat and reduces the supply of oxygen. The surface tension of water is also broken down and more of the water is absorbed into the surface of the fuel. This additional fuel moisture will absorb more heat in being changed to steam and driven off. Consequently, more heat is required to reach ignition temperature. The use of foam can be very effective in prescribed burning.
Fires burning in forest fuels are difficult to completely smother with dirt, even when damp because of the porous nature of most soils. It can slow down the fire however, by reducing its intensity. Water is more effective but the excess quickly runs off. Foams and retardants are most effective because they are long-lasting.
Removing the fuel source is the most common method of attacking wildfires and holding prescribed fires. This method does not extinguish the fire. The fire continues to burn until the fuel that is still available is consumed. Removal of fuel in the path of the fire prevents the fire from spreading past the fireline. A slowly advancing fire burning ground or surface fuels may be checked by constructing a fireline down to mineral soil. A hot, fast-running fire may require several firelines and/or burning out the remaining fuel between the fireline and the fire.
Chemical retardants (applied from the ground or by air) also remove the fuel by coating with a barrier that protects the fuel from preheating as well as cutting off the supply of oxygen. The available fuel thus becomes unavailable fuel. Retardants are also long lasting. They continue to be effective even after the water, used as a carrier, has evaporated.
Good firefighting procedure is often a skillful combination of removing fuel, heat, and oxygen. Therefore, when you tackle a going fire, you should consider how best you can use personnel and equipment to remove one or all of the sides of the fire triangle.
Never attach a “raging” fire from the front!
Never fight fire going downhill to the fire! Fire burns very aggressively up hill and can quite often develop its own wind turning it into a head fire.
Know the 10 basic fire fighting rules and don’t vary from them. No fire is worth a person’s life!