This is called a Class D fire and the application of water will exacerbate the combustion. Fires involving metals such as titanium, lithium and magnesium have a chemical reaction that requires a different approach for firefighters. The fire tetrahedron adds another element to the fire, which is chemical reaction. In large fires where firefighters are called in, decreasing the amount of oxygen is not usually an option because there is no effective way to make that happen in an extended area.Īn alternative to the fire triangle model is the fire tetrahedron. That is why one recommendation for extinguishing a small fire is to smother it with a non-flammable blanket, sand or dirt.Ī decrease in the concentration of oxygen retards the combustion process.
A fire needs oxygen to start and continue. The final element of the fire triangle is oxygen, which is also an essential component of fire. If a fire is allowed to burn without any attempt to extinguish it, as in the case of a controlled burn conducted by the Forest Service, it will extinguish on its own when it is consumed all of the fuel. Once the fuel element of the fire triangle is removed, the fire will go out. The fuel source can be anything that is flammable, such as wood, paper, fabric, or chemicals. A fire needs a fuel source in order to burn.
The second element in the fire triangle is fuel. Firefighters will also turn off the electricity in a burning building to remove a source of heat. Another cooling agent is a chemical fire retardant, such as the ones used in fire extinguishers.Īnother method of diffusing heat from a fire is to scrape the embers from the fire source, such as wood embers on a burning building. One of the first things firefighters do to extinguish a fire is to apply a cooling agent – usually water.