A fire retardant is a substance that helps to delay or prevent combustion. Fire retardants are commonly used in fire fighting. Water is the most commonly used fire retardant, but the phrase typically refers to chemical retardants. It can also refer to a coating over an object, such as a spray retardant to prevent Christmas trees from burning.
Home fires damage about 400,000 homes, and cause just under 7 billion US dollars in direct damage annually in the United States. Because of the importance of prevention, fire retardation has become a very important industry.
In general, fire retardants reduce the flammability of materials by either blocking the fire physically or by initiating a chemical reaction that stops the fire.
Class A foam is used as a fire retardant in 2.5 gallon APW and CAFS extinguishers to contain incipient brush fires and grass fires by creating a fire break. Other chemical retardants such as FireAde and Arctic Fire are capable of rendering class A material and Class B fuels non-flammable and extinguishing class A,B, and some D fires. (Fire retardant,such as the slurry dropped from aircraft, is used to prevent ignition while fire suppression agents are used to extinguish fires.)
It is possible to coat an object with a fire retardant. The classic example of this is the green Christmas tree. As a tree dries out it can be accidentally lit on fire putting the home at risk. A coating of a specialised fire retardant can prevent the starting of the fire and slow it down if it does start.
Most clothing intended for children in the United States is required to pass fire-retardant tests for safety reasons.
In many locations mattresses are now treated with fire retardant or built with fire-resistant material. Many new foams self-extinguish. This is the most common use of fire retardancy in the chemical means.
For More Information: Fire Classes & Control
Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License)