Halon Extinguisher Explained #safetyin180sec PART 21 #sundeepkumaronline #fireextinguisher #safety

Halon Extinguisher

Halogenated hydrocarbons (Halons) are a group of extinguishing agents, which, are stored under pressure in liquid form and released in such a way as to vaporise readily in a fire zone. They extinguish fire mainly by interfering with the chemical reaction involved in the propagation of flame. They possess little cooling effect. Halons can be effectively used in class B and C fires especially in confined spaces. They are electrically non-conductive and safe to use on electrical of electronic equipment’s and cause little damage. Halons are hydrocarbon compounds of a group of five non-metallic elements known as halogens i.e., Fluorine, Chlorine, Bromine, Iodine and Astatine. For various reasons Iodine and Astatine are not suitable for extinguishants and can be ignored.
Characteristics of Halon
(1) Their efficiency as extinguishing agents
(2) Toxicity, including that of their products on decomposition
(3) Physical properties e.g., boiling and freezing points
(4) Effect on materials with which they come in contact

Identification
The actual names of the Halons are shortened to sets of initial letters as under: -
Bromotrifluromethane Initials : BTM Halon number : 1301
Bromochlorodifluoromethane Initials : BCF Halon number : 1211
Dibromotetrafluroethane Initials : DTE Halon number : 2402
Chlorobromomethane Initials : CBM Halon number : 1011
Carbon tetrachloride Initials : CTC Halon number : 104
Methalebromide Initials : MB Halon number : 1001

Halons 1301 and 1211 are the least toxic. The exposure of personnel to these agents during firefighting is likely to be well within the maximum safe values, except where a total flooding system is being discharged. In a fire situation a further aspect to be considered is the effect of the decomposition products of Halons. They are much more toxic than the Halons themselves. However, it is the combustion products of the actual fire such as smoke and carbon monoxide, which, present the greatest hazard. Halons should not be used on chemicals containing their own oxygen. They should not be used on reactive metals and metal hydrates.
Types of Extinguishers
Portable Halon extinguishers commonly range from 500 gms to 7 Kg and are invariably of the stored pressured type. They are normally pressurised to about 10 bar with dry nitrogen to ensure efficient discharge. Most halon extinguishers have their discharge controlled by a lever but a few designs have striker.

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