"Ron Natalie" wrote in message
m...
Have you ever used a Halon fire extinguisher?

Yup. I have fought actual aircraft fires using Halon, Dry Chemical (both
"Purple K" and "Super K"), Protein foam, CO2, etc., etc. For a picture, see
http://temp.corvetteforum.net/c4/elw...mp/oysters.jpg or
http://tinyurl.com/csndg . That's me in the middle next to the pilot's
seat. All those little black dots are fresh oysters he was bringing back
from Canada. The white stuff is Dry Chemical - 1,500 pounds of it. It
wouldn't stop the fire until we covered it with foam. Items like the burning
tires would reignite the gasoline behind us after we had moved the hose line
past. Had to replace my bunking outfit after that one - too many burn holes
to repair it.

With a flood system and a relatively closed space it takes a long
time for the Halon to disapate. Try lighting a lighter in a space
near where halon has been discharged.

I spent several years inspecting, discharging and signing off fixed Halon
system in computer rooms, satellite communications buildings, and one
180,000 sq. ft. building for Boeing that I can't even talk about. There are
no areas on a light aircraft which are sealed tightly enough to establish or
maintain a proper concentration of Halon. You can "overkill" a simple pan
fire with a portable extinguisher, but that won't work on an engine
compartment fire when you're in the cockpit.

Halon is a wonderful product, for it's purpose.

Of course, much of what you said also applies to CO2. If the CO2 doesn't
cool down the metal (which admittedly it has a higher
capacity to do than Halon), then you have the same (actually larger)
reignition problems.

Some other factors must be considered with CO2. Being heavier than air, it
tends to settle in a low spot - very important in ship fires. Halon diffuses
throughout the space. I'm not sure how the Latent Heat of Vaporization
compares between Halon and CO2. In either case the cooling capability is a
very minor effect when it comes to extinguishment. If you want cooling, use
water. If you want to secure the area and prevent reignition, use foam.

In a three-dimensional fire such as an aircraft fire, all bets are off. Even
foam may not prevent reignition. Trust me - it is scary to be wading in Jet
A trying to plug a leaking tank when the stream coming from the tank keeps
igniting. Even in a drill. 8-}

Rich S.