suppressing the flames or altering the chemical reactions that sustain the fire. For example, the application of a dry chemical fire extinguisher.
Without enough heat, a fire cannot begin or continue. Heat can be removed by applying water, where the heat turns to steam, taking the heat with it. It should be noted that the application of water can cause some types of fire to spread. For example, applying water to hot oil or fat fires. Turning off the electricity in the event of an electrically related fire removes the heat source, although fuels that are still burning may continue to burn.
Oxygen can be removed from a fire by smothering the fire with an extinguishing agent, such as carbon dioxide, or covering a chip pan fire with a fire blanket. The fire triangle remains an effective teaching tool but does not demonstrate the fourth element of fire, the sustaining chemical reaction. This has led to the development of the fire tetrahedron. In most circumstances, the fire will fail to ignite, or is extinguished, depending on which element is removed. There are certain chemical fires where knowledge of the fire tetrahedron is essential. The following diagram is a two-dimensional representation of the tetrahedron, it is useful to visualise the fire tetrahedron as a pyramid, having four sides including the bottom.
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