Date: Sun Feb 17 12:34:34 2008 Back to Contents

Author: Stan Dodds

Subject: Re: Novec 1230

Halon (trade name for two different compounds) is another interesting
example. It apparently works by competing for free radicals in the
combustion reactions, effectively killing the fire by direct chemical
reaction. It was popular through the 1960s for use in computer rooms
and similar high-value areas because it did not cause excess damage.
Because it is not apparently toxic in the short term at concentrations
up to a few percent, but can suppress fires at that level, it was
particularly attractive for occupied, enclosed spaces. Usage has now
been largely discontinued because it damages the ozone layer, and
manufacture is banned by the Montreal protocol.

I have actually seen Halon used once, in a safety demo. The lecturer
put some gasoline in a wash tub and lit it. He then showed that a CO2
extinguisher just blew flaming gasoline around, without much other
effect. A short puff of Halon put the fire out immediately. The Halon
gas is heavier than air, so it settled into the tub and prevented
reignition when he tossed in another match. Goes to show that even a
safety lecture can be memorable with a good demo.


On Feb 17, 2008, at 9:51 AM, Marc "Zeke" Kossover wrote:

> The fire suppressants are really interesting. Some work by displacing
> oxygen and some work by cooling the fire below its activation energy.
> Many are very toxic. If you look at the MSDS for Novec 1230, it's not
> particularly toxic. It looks like something that would be fun to play
> with in the lab.
> Zeke Kossover

From Sun Feb 17 12:34:34 2008