Scott,
I beg to disagree, ... but, Halon, along with Freon and other compounds was
banned by the Montreal Protocol, ostensibly to protect the ozone layer.
Interestingly, the Freon replacements must, per the treaty, be phased out in
20 years - by coincidence about the time when the international patents
expire. No suitable replacement for Halon has yet been found, and the U.S.
military has bought up much of the existing stocks for vehicle and shipboard
fire protection systems. If I remember correctly, Halon can cause
suffocation by displacing oxygen, rather than causing toxicity. When I
worked in a Halon protected room, our instructions were to take a couple of
deep breaths before the system fired, and hold our breath during escape.
Scott Lacey
-----Original Message-----
From: Scott Douglas [SMTP:[email protected]]
Sent: Wednesday, November 17, 1999 1:53 PM
To: [email protected]; [email protected]
Subject: RE: Shielded Enclosure Fire Hazard
George,
I once worked in a laboratory that developed the Doppler weather
radar we
all see on TV today. In our just built (in 1979) control room, they
put a
halogen extinguisher system. Halogen works by displacing the oxygen
and thus
the fuel for the fire. No fuel, no fire. The system could fill the
entire
control room, 50' x 80' in less than 30 seconds. We had big klaxon
alarms
and a disable mechanism, but strict rules to just run like hell. We
had a 10
second warning bell that went off just before the gas came down.
Point is,
it wasn't so much the ozone layer that made halogen fall out of
favor, it
was the severe threat to human life. The gas is odorless, tasteless
and
invisible, so if it went off you wouldn't know until too late. I
recall they
told us that you would not live 30 seconds in a room filled with
halogen.
The several false alarms caused us to evacuate and we had to call
the fire
department to ventilate the building for 60 minutes before we could
get back
to work. Halogen is certainly an extremely effective means of
suppressing
fire, but operating costs and impact on operations play a big part
in its
use (or lack thereof). The gas is expensive and, while there is
little
damage to facilities or equipment from its use, there can be human
consequences to deal with.
Scott
[email protected]
ECRM Incorporated
Tewksbury, MA USA
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