Scott,
I presume you mean Halon, not halogen. Sorry, but Halon systems are
neither invisible nor odourless. When you set one off, the room fills with
a smoky haze that has quite a strong odour. I presume that this is due to
additives that are included for the very purpose of making it obvious.
By the way, when you set one of these things off, there is a very loud,
explosive noise. Not sure if this is due to an explosives charge opening
the pressurized cylinder, or just the explosive expansion of the
gas. Regardless, you'd have to be deaf (and blind) to not realize that the
system had deployed.
In a previous incarnation, I used to work on oil rigs in the Arctic
Ocean. I once had the dubious distinction of setting one of these things
off (due to a tantalum cap on one of my PWBs). Just imagine sitting there
in the middle of winter, in that complete silence of the Arctic, and all of
a sudden there is this incredible explosion and smoke ...
Needless to say, a change of underwear was in order.
No, there is no danger of missing the fact that there is halon in the
air. As for breathing the stuff, I'm not aware of any actual harm. Yes,
it displaces the normal oxygen, so you obviously can't live on it, but it's
not poisonous, just neutral. I'm sure I got quite a lungfull of the stuff,
but there was no harm done. No big deal.
Egon :-)
At 12:25 PM 17/11/1999 , you wrote:
----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
__________________________________________
Egon H. Varju, PEng
E.H. Varju & Associates Ltd.
North Vancouver, Canada
Tel: 1 604 985 5710 HAVE MODEM
Fax: 1 604 273 5815 WILL TRAVEL
E-mail: [email protected]
[email protected]
__________________________________________
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