[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Halon

>CO2 displaces the O2 in the area of the fire until combustion can 
>no longer be supported.

While this is possible, it is without a doubt the worst possible way
to use a CO2 extinguisher, and probably will not work. If it did
work this way, yes indeed you would be dead from the result. At high
concentrations your lungs will soak up CO2 from the air and this
will prevent your blood from absorbing O2. That is just the way
blood chemistry works.

C02 works by becoming very cold as it expands from the tank. The
cold gas then freezes whatever is on fire, dropping the temperature
below what it takes to sustain the fire. This is why a CO2
extinguisher must be put right up against whatever is on fire, not
used from a distance. I learned this the hard way, by *nearly*
putting out a fire with CO2, and then having it come right back
again because the underlying structure was still hot. I asked the
fire-folks who eventualy showed up what had happened, and they told
me that I had used the CO2 the wrong way, the way virtually
everybody does.

>I don't know how Halon works chemically (perhaps someone knows
>and could explain?).

Halon works because it contains contains chemicals like F, Cl, and
Br. All of these elements are in the next-to-the-right-most column
in the periodic table, and they just love to soak up any electrons
which are available. Fire is rapid oxidation, which really comes
down to the transfer of electrons from one chemical species to
another. The Halon soaks up the electrons which would have been
transfered from the flame source to O2, but without breaking apart
and recombining with the fuel and releasing enough heat to keep the
reaction going, and that prevents the fire from continueing.