What is the key element necessary for a fire to sustain itself, besides fuel and oxygen?

The key element necessary for a fire to sustain itself, in addition to fuel and oxygen, is heat. In the fire triangle, which is a model for understanding the necessary ingredients for fire, heat is crucial as it raises the temperature of the combustible material to its ignition point, allowing the combustion process to occur.

When sufficient heat is present, it facilitates the chemical reactions between the fuel and oxygen, thus enabling the fire to continue burning. If you remove heat from the equation, even if you have fuel and oxygen, the fire will be unable to sustain itself and will eventually extinguish.

Wind, pressure, and water do not serve as fundamental elements in the sense of sustaining combustion. While wind can influence fire spread by supplying oxygen and removing heat, it is not classified as one of the essential components in the fire triangle. Pressure plays a role in fire behavior but is not a basic requirement for fire to occur, and water is a common extinguishing agent used to cool heat and limit the fire, rather than something that sustains it. Thus, heat is the critical element needed alongside fuel and oxygen to maintain a fire.