On Sun, 02 May 2004 16:01:47 GMT, "Jürgen Exner"
wrote:

O. Sami Saydjari wrote:
I just got my first issue of "Light Plane Maintenance" magazine.
I am really enjoying it. In their free book "40 Top Maintenance Tips"
(p27), they say "get the Halon extinguisher while they are still
legal."

Halon has been banned years ago because it is one of the worst chemicals
wrt. destroying the ozone layer.

It was widely used in the 70s and possibly into the 80s, particularly
in computer rooms that might contain lots of personnel.

At several installations we had large process control computer rooms
That used Halon from large tanks located on a lower floor. It's been
a while but I'd guess these tanks might have been as large as 150
gallons. They were connected to the computer rooms through either a 3"
or 4" header pipe that had a number of outlets. These outlets did not
have fuseable links, or diffusers on them as with water. They were
wide open pipes and an extinguisher dump was something you did not
want to experience more than once.

Although these rooms were large, there weren't *that* large. They
were solid and tight, separated from the processes by a "blast wall".

I saw a 1 1/2 steel door that had been bent from an extinguisher dump.
The door was open about 1/3 of the way when the dump occurred. Had
the frame not been set in reinforced concrete it would have blown the
door in a spectacular fashion.


As I recall, there has been some issue that inhaling Halon can be
pretty bad for people's health.

There are several "gotchas" with Halon, but "in general you can inhale
Halon with no ill effects.

It is my understanding that it works differently than other
extinguishers by inhibiting the combustion process while still leaving
enough Oxygen in the air for survival.


Not really. Halon is non-toxic.

OTOH although Halon is non-toxic, at high temperatures it can generate
some very toxic gases. Really nasty stuff when it is broken down into
it's basic constituents.


Why is a Halon fire extinguisher a
great idea.

Because is it is non-toxic, very effective, non-corrosive, non-damaging,
doesn't leave a residue, and half a dozen other reasons.

To my way of thinking there are about the only safe thing to use in an
aircraft. Many have dry chemical extinguishers and using one of those
in a confined area is ... quite an experience. It'll leave a taste
in your mouth for quite a while, but you shouldn't suffer from acid
indigestion for a while be it a standard or Purple K (TM) charge.


Also, this might sound dumb, but don't C02 extringuisher work by
depriving fires of 0xygen?

Plus cooling the fire below the ingnition temperature.

It seems to me that in a small aircraft
cabin, one might also end up depriving the pilot and crew of oxygen as
well.

With the airflow through most small aircraft I'm not sure the CO2
extinguisher would be all that effective.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


Only a concern for prolonged exposure.

Perhaps, one can survive long enough to put out the fire and
then open the air vents?!

Normal ventilation would probably even be enough.

jue