Search Safety Home Knowledge Fixed Fire Fighting Gas Halon 1301 Bromotrichlhoromethane CF3Br A colorless odourless gas. As a gas it is noncorrosive, when it is dissolved in water it is highly corrosive .Nitrogen for superpressurisation is added due to the low pressure energy of halon, typically to 42bar at 20 o C by a little understood process it disrupts the chain of reaction that is combustion thus extinguishing fires. Toxicity When comparing toxicity to extinguishing concentration halon is the safest agent. Concentrations upt to 7% can be breathed for 5 minutes without effect, at 10% this is reduced to 1 minute. At a temperature above 510 o C halon will decompose. Two of the most important products are Hydrogen Bromide (HBr) and Hydrogen Fluoride (HF). In small concentrations these gases are an irritant which will forewarn personnel of increasing concentrations. It is considered that these gases pose a much lesser threat than the other products of fire poisonous smoke, carbon monoxide etc. Required concentration A concentration of 4.25 to 5% by volume is required Advantages clean with no residue Easy and safe to store Electrically nonconductive Good penetration Suited to automatic release Low working concentrations means relatively safe for personnel Fast Regulations Only permitted machinery space, pump rooms or cargo spaces solely for carriage of vehicles not carrying cargo. No new installations System designed so minimum quantity of medium is discharged to space based on liquid phase within 20s Means of safely checking pressures Volume 0.16m 3 /Kg Fire resistant release mechanism Over pressure device fitted Leakage warning alarm for locally operated devices the concentration should not go above 7% not halon 1301 and 5.5% for halon 1211 at 20 o C, discharge time for liquid phase no more than 10s Montreal convention Following the Montreal protocol the usage of Halons was agreed to be phased out by the year 2000 and halved by the year 1995. In response to this, IMO has planned the following; No new installations after July 1992
