Q. Canadian Homebuilt: Fire Extinguishers - Halon

There are a few Aqueous Fire Fighting Foams (AFFF not sure if that is a
recognized acronym or just Sales Hype)systems out there now to replace
Halon in Auto Racing applications, has anyones heard whether one of
these might be a viable alternative?

Mike Butler

A triple F is wonderful stuff. I've trained with it for fighting
underground mine fires. Since it's mostly water an extinguisher big
enough to do any good would be very heavy. probably not the best
choice for an on board extinguisher.

Drew Dalgleish wrote:

A triple F is wonderful stuff. I've trained with it for fighting
underground mine fires. Since it's mostly water an extinguisher big
enough to do any good would be very heavy. probably not the best
choice for an on board extinguisher.

From what I can tell in the auto racing catalogs (Pegasus for one,
http://s2.pegasusautoracing.com/026.pdf), there are systems from 2 to 4
liters weighing about 7 and 16 lbs respectively. These are being
marketed as direct replacements for the 5 and 10lb Halon systems. I
realize it is much easier to get out of a burning race car even if it is
doing 160 mph or better than almost any airplane but the systems look
interesting. Most open wheel cars I used to run use the 5lb Halon
systems to meet the SCCA rules. Even with the larger 4L system it seems
to me the 16 or so pounds might buy some very valuable time in an airplane.

Mike Butler

"Drew Dalgleish" wrote in message
...


There are a few Aqueous Fire Fighting Foams (AFFF not sure if that is a
recognized acronym or just Sales Hype)systems out there now to replace
Halon in Auto Racing applications, has anyones heard whether one of
these might be a viable alternative?

Mike Butler

A triple F is wonderful stuff. I've trained with it for fighting
underground mine fires. Since it's mostly water an extinguisher big
enough to do any good would be very heavy. probably not the best
choice for an on board extinguisher.

You are right on, Drew! That stuff rocks. I couldn't think of the term right
away. When a bunch of us let a drill fire get away down at Boeing Field one
time, we fought it with a couple of 2-1/2 lines for about twenty minutes.
When it became apparent we were over our head, Boeing's Attack rig hit it
with a ten-second burst of AFFF. It went out, NOW. The driver leaned out the
door with his hanky and wiped the last drip or two off the nozzle.

Man, that takes me back. . .

Rich S.

P.S. It's Aqueous Film Forming Foams.

On Tue, 19 Jul 2005 15:11:53 GMT, "Cy Galley"
wrote:

the key statement is...

"It is likely impossible under an aircraft cowling when the plane is
moving. "

For this application it is a waste of weight, money, and time.

I remember a "discovery" or "military weapons" show I watched one time
where they were attempting to find a substitute for the Halon based
fire extinguishing system being used on some military jet.

They demonstrated the ability of the Halon system to put out a fire
created by a 20mm cannon hit, under controlled conditions. The
conditions included being in a wind tunnel, or directing high speed
air onto the area to be hit to simulate relatively high speed flight.

The Halon based system did a pretty good job of snuffing the fire out
from the cannon shell hit, even while the flame was being fanned by
the high speed air. Must have been a lot of Halon, I guess.

None of the other types of systems shown seemed to work quite so well.

This all came to be because Halon is a CFC, as is the refrigerant
R-12. They are both similar inert gasses. I recall a demonstration
one time wherein this guy breathed in from a hose of R-12, and then
breathed out over a lit candle. The R-12 settled over the flame and
extinguished it.

As a mechanic back in the 70's, we used to discharge that stuff all
over the place. It didn't matter we were told, it was an inert gas...

Corky Scott

Thanks for the feedback to all.

We're now off to Oshkosh, with a detour over northern NY, then off to
Oshkosh via Chicago.

Cheers.

Airventure ... the world's biggest aviation toy store :-)

Corky Scott wrote:


This all came to be because Halon is a CFC, as is the refrigerant
R-12. They are both similar inert gasses.

They ARE very stable, but not 'inert gasses'.

Historically 'inert gasses' were a handful of chemical elements,
that in their natural state at room temperature were monatomic
gasses, and which would not form any chemical compounds under
any conditions.

Sometime after the mid 20th century some shortlived compounds of
Neon (and maybe some others) were formed under laboratory conditions.
Consequently, the proper term for these gasses was changed to
'noble' gasses, meaning the were reluctant to combine with other
elements, but not completely inert.

AFAIK 'inert gas' remains as an archaic term synominous with
'noble gas'.

... It didn't matter we were told, it was an inert gas...


I think welders use the term 'inert gas' for any gas that will
not ready with the metal they are welding by whatever technique
they are using. But CFCs/Freons never qualified as 'inert'
even by that defintion.

Oh well, such is the nature of slang.

I remember the screens used to support a beaker over a bunsen
burner. they had a disc of asbestos in the middle so the flame
would not burn through the wire. Bet those were a great source of
airborne asbestos fibers.

--

FF

On 20 Jul 2005 10:43:08 -0700, wrote:

They ARE very stable, but not 'inert gasses'.

I stand corrected, the guy demo'd how to service automotive A/C
systems, I doubt he was a trained chemist. I for sure didn't know
enough chemistry to challenge, or even know the difference. ;-)

I was just impressed that anyone would inhale the stuff.

Corky Scott

"Teamfcar" wrote

Even with the larger 4L system it seems
to me the 16 or so pounds might buy some very valuable time in an
airplane.

Where would you chose to have the system protecting, the cockpit or under
the cowl, and why?
--
Jim in NC

Morgans wrote:
"Teamfcar" wrote


Even with the larger 4L system it seems
to me the 16 or so pounds might buy some very valuable time in an
airplane.


Where would you chose to have the system protecting, the cockpit or under
the cowl, and why?

I cannot make a qualified answer for aircraft, but the SCCA requires one
nozzle for the engine bay and another for the Driver in the cockpit. A
5 lb Halon will go for 30 or 40 seconds from two nozzles In the engine
bay we usually aimed it at the carburetors (Dual Webers side drafts or
Fuel Injection) such that it would end up down on the oil pumps. As it
was explained to me the two most flammable things in the engine are the
fuel and the oil. In the cockpit it was right behind the dash aimed
down and back to cover the drivers legs and flow back up his torso. In
most cases in open wheel racing, the fuel cell either forms the back of
the seat or is nested to the back of the drivers seat. So that would be
the most likely source to feed any flames in the cockpit. In an
aircraft I would probably use the same ideas to allow the prevailing air
stream carry the AFFF or Halon to the likely site of the flames.

Mike Butler

Corky Scott wrote:

...

I was just impressed that anyone would inhale the stuff.


I'm impressed also, and not favorably. Although CFC refrigerant
itself is non-toxic, like air from a shop compressor it usually
contains trace contamination by lubricants making it dangerous
to inhale.

Ditto for helium sold to inflate balloons. Sure, you can make
your voice sound funny but you can get chemical pnemonia too.

--

FF