The Fire Triangle
A fire requires three basic components – fuel, air and heat. To control the fire, at least one of them must be removed.
7 May 2008 | Updated 14 October 2011
For a fire to thrive and spread it requires three things:
• fuel for the fire to burn
• air for the fire to breathe
• heat for the fire to continue burning.
Removal of any one of the sides of this Fire Triangle will extinguish the fire.
If fuel is removed, the fire will starve and be extinguished. With bushfires this can be done through a number of pre-emptive methods, including prescribed burning or physical removal of the fuel.
During wildfire suppression the removal of fuel can be done physically through the raking of fire line or the use of bulldozers to clear a fire line.
The removal of fuel can also be done through the lighting of small controlled fires to remove the fuel ahead of the fire. These fires, called burn-out fires, are lit from control lines and must only be done by experienced firefighters and well-supervised crews.
If air is removed, the fire will suffocate – because of a lack of oxygen – and go out. The removal of air from a bushfire is quite difficult as fires are normally quite big and encompass considerable area.
The removal of heat is the most common form of fire suppression.
There are methods of suppression, however, that work on the basis of suffocating the fire.
Water-based foam sprayed on to the fire will act as a blanket between the fire and the air. Similarly, a layer of dirt shovelled onto the fire will act as a blanket.
The removal of air from a fire is a form of attack that is normally only limited to small or easily accessible fires.
The removal of heat or the cooling of a fire is the most common form of suppression.
In most cases water is used to essentially soak up the heat generated by the fire. This heat turns the water in to steam, thereby robbing the fire of the heat used.
Without energy in the form of heat the fire cannot heat unburnt fuels to ignition temperature and the fire will eventually go out. In addition, the water can act to smother the flames and suffocate the fire.
Chemicals can be added to water to improve the heat removal properties of water, or to improve the ability of the water to stick to unburnt fuel.
Learn more about our bushfire research in Bushfires.