A
colorless odourless gas. As a gas it is non-corrosive, when it is dissolved in
water it is highly corrosive .Nitrogen for super-pressurisation is added due to
the low pressure energy of halon, typically to 42bar at 20oC
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 510oC 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 non-conductive
·
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 0.16m3/Kg
·
Fire resistant release mechanism
·
Over pressure device fitted
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