Directions: Move your mouse over the figure to discover more about the four elements of fire.
Fuel
- Fuel is any substance that can undergo combustion.
- Fuel can be in the form of a solid, liquid, or gas.
- When the energy of the fuel is released, it produces heat, light, and other forms of radiant energy.
Heat
- To start a fire, sufficient heat must be applied to begin the process.
- The heat must be sufficient to raise the fuel to above its ignition temperature (to turn liquid and solid fuel source materials into vapour that burns).
- When fire is able to produce heat by releasing energy and maintain the necessary level of heat, it becomes self-sustaining; that is, it keeps going on its own.
Oxygen
- Oxygen is a gas that is consumed by fire.
- Increasing oxygen increases the intensity of the fire
- Removing oxygen extinguishes a fire.
Chemical Reaction
- A fire is a chemical reaction.
- Although fuel, heat, and oxygen are required to light a fire, a sustained chemical reaction (a rearrangement of molecules) is required for a fire to continue.
- Fires produce free radicals that act to continue the chemical reaction of the fire.
- If the free radicals (uncharged molecules - typically highly reactive and short-lived) are removed, the chemical reaction (a rearrangement of molecules) will not continue and the fire will go out.