Fire technology

Fire technology

The application of results of basic research and of engineering principles to the solution of practical fire protection problems, but entailing, in its own right, research into fire phenomena and fire experience.

The contribution of the practices of fire prevention is potentially much greater than that of the actual fire-fighting activities. Fire-prevention and loss-reduction measures take many forms, including fire-safe building codes, periodic inspection of premises, fire-detection and automatic fire-suppression systems in industrial and public buildings, the substitution of flame-retardant materials for their more flammable counterparts, and the investigation of fires of suspicious origin, serving to deter the fraudulent and illegal use of fire.

The fundamental techniques used by fire fighters consist primarily of putting water on a fire. Water serves to cool a burning material down to a point where it does not produce gases that burn. While water is the most practical and inexpensive extinguishing agent, modern technology has provided not only additives to water to render desirable properties such as easy flow or enhanced sticking, but also chemical and physical extinguishants such as fluorocarbons, surfactant film-forming proteins, and foams.

A general approach to fire control has been developed involving use of flame inhibitors. Unlike older fire-extinguishing materials such as water and carbon dioxide, these agents operate indirectly in that they interfere with those reactions within a flame that lead to sustained release of heat. As a result, temperature of the system falls below ignition temperature. The most effective liquids are the halogenated hydrocarbons such as chlorobromomethane (CB) and bromotrifluoromethane (better know as Halon 1301) which are colorless, odorless, and electrically nonconductive.

In dry-powder chemical extinguishers, ammonium dihydrogen phosphate is the most useful fire inhibitor. Other dry-powder inhibitors are salts of alkali metals (which include lithium, sodium, potassium, rubidium, and cesium).

Foams are also widely used. Protein-type, low-expansion foams, particularly useful in quenching burning volatile petroleum products, are used in crash-rescue operations. High-expansion foams are available for fire suppression in enclosed areas. Some foams of this type are generated at a rate of 15,000 ft³/min (424.8 m³/min). They can contain sufficient air to allow a human to breathe inside them.

A film-forming solution of a specific fluorocarbon surfactant in water, known as light water, was developed by the U.S. Navy for use with dry chemicals to fight aircraft crash fires. It may be used either as a liquid or as a low-expansion foam to interfere with the release of flammable vapors from the burning fuel. Light water is also useful in extinguishing petroleum storage tank fires and may find application to urban fires once the cost is no longer prohibitive.