From: John De Armond
Subject: Re: Fire Extinguishers
Date: Wed, 22 Aug 2001 04:01:28 -0400
> >halon was selected for fire suppression in large part precisely
> >because it does NOT produce any significant quantity of toxic
> That's what I thought John. I knew that it displaced the O2 and in an enclosed
> area can suffocate a person, but Lon's post really tossed me for a loop...
Yeah, me too. I hate to think what OTHER sort of BS is presented in
similar "seminars". One of the things my nuclear engineering
company used to do was to commission and test Halon fire suppression
systems in nuclear plants. Wasn't my specialty and I had fire
protection engineers who were the experts but as the 10CFR21
responsible party for my company, I stayed in the loop and was
present at all tests. The huge advantage of Halon _IS_ that it
suppresses (actually interrupts) fire while in a low enough
concentration to support life. The specified concentration to
achieve in the protected space after discharge is 10%. There is
still enough oxygen to breathe at that concentration. Halon does
little more than make your a little buzzy so there's no danger if
you get trapped in spaces during a discharge.
Contrast that with Cardox (liquid carbon dioxide), the only other
viable non-soiling flooding system. CO2 extinguishes fire by
smothering. It extinguishes life the same way. I was in the
computer room at the Browns Ferry nuclear plant when some idiot test
engineer manually tripped the Cardox valve, flooding the room
without warning. We had about 3 seconds of warning from the air
rushing out of the pipes. Then whiteout. Eight of us cleared the
room via one door simultaneously. It was no more than 5 steps from
where I was sitting to the door and yet by the time I got there -
whiteout. My eyes burned, my throat felt like a hand was crushing
it and I was headed toward frostbite as the CO2 snow piled up around
my feet. If I'd been another 5 steps away or, God forbid, inside
one of the cabinets, they'd probably have dragged me out by my
Funny this topic comes up. During the World's Longest Yard Sale on
hwy-127 last weekend I happened to run into the engineer who was
responsible for that system and for whom the knucklehead who tripped
the system worked. Lots of war stories swapped.
> BTW, wasn't one of the Halon compounds banned... I vaguely remember hearing
> something about this sometime ago, but couldn't prove it one way or the other.
> I thought I remembered reading something in the NHRA rulebook...
The manufacture of Halon was banned just like freon as the result of
the ozone hysteria. It is no longer made but existing stocks can be
deployed until exhausted. Halon extinguishers and fire suppression
systems are still available but they bring a pretty penny.
The ozone lunacy is especially stark regarding Halon. Wild claims
by certain companies to the contrary, there is simply nothing else
that provides the same level of protection as Halon. Apparently
sacrificing real lives at the altar of the Ozone myth is OK in the
minds of the True Believers.
From: John De Armond
Subject: Re: Fire Extinguishers
Date: Wed, 22 Aug 2001 04:08:36 -0400
Larrie Malobenski wrote:
> Though hard to find CO2 extinguishers are handy for RV's. No residue,
> multiple uses before recharging and useful against snakes and attacking
And the primary use they were put to when I worked for TVA - rapid
chilling a 6-pack of your favorite beverage. Just drop a few cans
down the horn, aim up in the air, pull the trigger, wait a few
seconds and drink :-)
Most any fire protection company should be able to fix anyone up
with a 10 lb CO2 extinguisher. The initial purchase is steep -
around $80 for a used one in this area (In essence, you're buying a
high pressure tank with a special valve fitted) but recharges are
cheap. I carry a 10 lb unit in my little rig. It is LARGE compared
to a dry chemical unit. I also carry a large dry chemical unit.
The CO2 won't last nearly as long as a dry chem unit so if the CO2
fails to completely knock down the fire, screw the mess, the dry
chem's coming out!!!
From: John De Armond
Subject: Re: Fire Extinguishers - Halon (longish)
Date: Thu, 23 Aug 2001 03:38:15 -0400
> John writes:
> >and burned under high pressure, it exits as phosgene gas.
> >This is what I think is the main constituent of "nerve gas' or
> >The products
> >are toxic (eg hydrogen flouride and hydrogen bromide) but being
> >irritants they give warning of their presence.
> So... is it "nerve gas" which normally isn't an irritant or is it "mustard gas"
> (or the like) which is? Nerve gas affects the nervous system. Usually the
> stuff is colorless, odorless, and tasteless and very deadly. Irritants such as
> phosgene, mustard, etc., are anything but odorless and tasteless. They seldom
> afffect the nervous system but instead attack the eyes, nose, throat, etc. of
> the victim.
Here is a good info page on Phosgene:
I worked with the stuff in college and can attest that this
description is correct, particularly the description of the odor.
It made a good war gas precisely because it didn't have a strong,
irritating odor upon first contact. The damage was latent and
showed up hours later when it was too late to do anything about.
Chlorine was a much poorer war gas because of its highly irritating
odor even in tiny quantities gives sufficient warning to move away
or seek protection if possible before a lethal concentration is
reached. Phosgene is obviously not a nerve agent, the most common
of which are complex organophosphates.
The first chlorinated hydrocarbon fire extinguishing agent was
carbon tetrachloride (remember the red throw balls that used to hang
on the walls of department stores?) Phosgene is the major
decomposition product of carbon tet in a fire, one reason its use as
an extinguishing agent was banned. And because it isn't a very good
agent. From my study of the topic, I believe that this is where the
phosgene-chlorinated hydrocarbon link was formed. It persists today
even though the formation of phosgene is not highly favored during
the decomposition of more complex halogenated hydrocarbons.
More usual with the decomposition of, say, freon, is the formation
of HCL, HF, chloramines (NH2Cl) and other similar simple molecules
and some phosgene. All of these EXCEPT phosgene are extremely
pungent and immediately irritating and are responsible for the
choking feeling and irritated airways from breathing even small
concentrations of decomp products. Chloramine is used increasingly
as the disinfecting agent in public water supplies because it lasts
longer than chlorine. Thus many people are familiar with the odor
of it even though they think it is "chlorine".
In the context of using Halon as an extinguishing agent, this is a
typical argument regarding angels dancing on the head of a pin. If
there is no fire, then there is no decomp products. If there is
controllable fire, the action of halon is so fast that very little
decomp products are produced before the fire is extinguished. They
are swamped by the smoke and heat produced before the agent is
applied. The immediate fire danger averted is much more important
than any (mostly) theoretical risk from decomp products. If the fire
is too large for the halon dump to control, one has much more to
worry about than the brief burp of decomp products!