HALON FIRE EXTINGUISHER PORTABLE
HALON FIRE EXTINGUISHER FREE

However, although these types are the most effective fire extinguishing agents in general use, they both leave a very fine, powdery residue after discharge which includes particles of sub-micron diameter which is difficult if not impossible to clean up. Both types may be used safely on fires where electrical circuits are present. Extinguishing agents in common use generally are either formulations based on sodium bicarbonate - suitable only for fires involving flammable liquids and gases - or those known as ‘ABC’ which are usually based upon ammonium phosphate and are suitable for use on fires of all origins. The search for Halon alternatives for use on aircraft has been in progress for at least 20 years and has only recently led to potential success in the form of the product marketed as 'Halotron'.

HALON FIRE EXTINGUISHER PORTABLE

Where a portable Halon extinguisher is used by cabin crew, it is usually recommended to consider donning a smoke hood before discharging it so as to eliminate this risk, but for pilot use on the flight deck, this will not be an option and risk awareness is the only defence. The toxicity of the Halon gases, especially the combination which makes up Halon 1211, is such that use in confined spaces requires care to minimise any inhalation of the discharged gases. The magnitude of this effect, however, is relatively small compared to chemical inhibition and thermal effects, the former of these being the predominant one.

Dilution is a simple matter of reducing the collision frequency of the oxygen and fuel source so that there is a reduction in chemical reaction rates. Halon gas mixtures are not only inert but of low temperature when released from their pressurised state. The rate of the combustive chemical reaction decreases rapidly with reductions in temperature and, if the concentration of added inert gas is high enough, the flame chemistry fails altogether. Temperature reduction occurs, whenever a non-reactive gas is added to a flammable gas, because the heat liberated by the reaction of oxygen molecules with a fuel source must be distributed into the overall environment.

HALON FIRE EXTINGUISHER FREE

Fluorine atoms react with free radicals and form strong chemical bonds which neutralise combustion but can only do so once and are then “consumed.” The physical effects are both temperature reduction and dilution.Bromine, Iodine and Chlorine atoms act catalytically so that each atom participates repeatedly in the scavenging of important free radicals from the combustion gases.The chemical effects, which are dominant in their overall effect, are achieved by the atoms in the gas directly inhibiting combustion in two different ways: How Halon Extinguishers Workīoth Halon variants work by a combination of chemical and physical effects. However, the search for alternatives of comparable effectiveness has proved difficult and success limited, so they remain in wide use on board aircraft for most applications. As a result, their manufacture and use have been banned for many years in most countries and non-essential uses have been eliminated. The chemical constituents in Halon gases, and the products of the reactions they induce when discharged on fires, have been identified as causing damage to the Ozone layer. However, the fumes are toxic if inhaled and all practicable precautions should be taken when they are used. They do not produce residues and therefore do not cause secondary damage. They work mainly by chemically interrupting the reaction described as the ' Fire Triangle' (Fuel-Oxygen-Heat) which must be sustained for a fire to continue. Halons are electrically non-conducting and have been acknowledged as the most effective universal extinguishing agent for aircraft use. Halon 1301 is used only in fixed extinguisher installations typically cargo holds or engines and is a total flooding agent.Halon 1211 is used only in portable extinguishers and is a streaming agent.They exist in two forms - as Halon 1211, BromoChlorodiFluoromethane (CBrClF2) also known as 'BCF', and as Halon 1301, Bromotrifluoromethane (CBrF3). Halons have, until recently, been in almost universal use in aircraft fire extinguishers, both portable and fixed. Halons are fire extinguishing agents which are gaseous when discharged in the aircraft environment.

Halon fire extinguisher