Halon agent fire extinguishers

For gases and vapors, the amount absorbed is highly dependent on the partial pressure of the gas and the solubility of the gas in blood. Let s take the simple case of a gas that is not metabolized and is excreted by exhalation (e.g., an anesthetic gas or a Halon-type fire-extinguishing agent). At any given concentration (or partial pressure) in the atmosphere, the concentration in the blood will reach a steady state in the blood. Accordingly, prolonged exposure does not lead to continual buildup. 

Today, fire-protection halons are subject to international restrictions imposed by the Montreal Protocol on Substances that Deplete the Stratospheric Ozone Layer. Consequently, production of these fire protection agents has been phased out as of January 1,1994. New halon replacements are now available. See NFPA 2001, Clean Agent Fire Extinguishing Systems. 

There are many uses for the halogenated hydrocarbons. Many of them are flammable most are combustible. Some halogenated hydrocarbons are classified as neither, and a few are excellent fire-extinguishing agents (the Halons ), but they will all decompose into smaller, more harmful molecular fragments when exposed to high temperatures for long periods of time. 

These next scenes are not sequences of an explosion, but of a burning torch being thrown into an open cublicle with an open pan of gasoline on the floor. In the cubicle is a UV fire detector and a 10-pound bottle of Halon 1301, an extinguishing agent. 

Trichloroethylene and 1,1,1-trichloroethane are used in correction fluids, dry-cleaning products, degreasing sprays, and solvents and spot removers. Bromochlorodifluoro-methane is a compound found in halon fire extinguishers that is abused. Freon is used for refrigeration and air conditioning systems. Anesthetics include halothane, chloroform, and the local anesthetic ethyl chloride. Methylene chloride is a component of rubber cement, paint strippers, and degreasing agents, and fluorocarbons are present in many types of aerosol sprays. 

In the case of the halons, replacements are also being phased in. For example, halon 1301 (bromotrifluoromethane, CF3Br), widely used as a fire-extinguishing agent to protect sensitive electronic equipment, is being replaced by HFC-227 (CF3CHFCF3), which contains no chlorine or bromine. 

Halon. [Great Lakes] Fire extinguishing agents. 

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