Which Fire Extinguisher is the right one to choose for my aircraft?

Sgtmac

Sgtmac

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Sgtmac
That was a good read.
Thanks for the info.
 
Lost me right away with "Tree things must come together" My advice would be: Get a smoke hood, no matter which fire extinguisher you choose.
 
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apparenlty the ABC extinguisher in a plane can be a death sentence for the structure and the electrical...plus instant IMC in the cockpit.
 
I used a fire extinguisher once. On the ground.

While trying to start the engine, I flooded it. Maybe the ignition source was a backfire, but I'm not sure.

Smoke started coming into the cabin through the windshield defroster. I immediately stopped cranking. I turned the fuel selector knob to off and got out of the plane rapidly.

The airport had a dry chemical extinguisher nearby, and it worked great. I sprayed it into the cowl two places, down the oil-check door and up the opening near the exhaust pipes. The smoke stopped right away.

It was a rental plane. It turned out that the only repairs needed were some new hoses and a washing.

For the cabin, in flight, you need halon. But I'd guess it's more common to use an extinguisher on the ground, as I did.
 
Ok, I'm confused. I work in IT and have had Halon training. I remember a value of 7% dilution with air being the critical point where Halon will cause you to black out. Not immediately, but if you don't get into clean air quickly then you will die.

If I take a cockpit which we can generously say is 5'x5'x8' or 40 cubic feet x .0724 lbs/cuft3 (for air), I get 2.8lbs of air in that cockpit. If I discharge 5 lbs of halon into that then we're talking more halon than air and something around 60% dilution. Almost immediately that Halon is also going to start blocking the fire yes - and it will start blocking my lung's ability to process oxygen. I will immediately begin the process of suffocation. If I don't get air within about 2-3 minutes, the airplane will be minus one pilot...although in fairness I'll be dead before the airplane reaches the ground. Even if I get onto the ground, if I can't get the concentration out of my lungs, I'll die anyway.

I don't believe a halon extinguisher is reasonable in flight and might be worse than a fire. The fire might kill you, if you use a halon extinguisher in a small airplane cockpit and cannot get out then it WILL kill you.

Am I missing something?
 
I guess I will have to add to my checklist, hold your breath use the fire extinguisher once the fire is extinguished open a door and start reading.
 
Opening a cessna side window, or cracking a door in flight will move LOTS of air.
 
Here's a pretty decent Halon Q&A narrative. See paragraph 5. An owner should have an idea of his extinguisher capacity relative to the cubic volume of the airplane. You can shoot enough to put out the fire and not threaten yourself. Especially since you can direct the Halon at the fire.

http://www.h3rcleanagents.com/support_faq_2.htm
 
I carry dry chemical because:
1) The likelihood of an in flight fire where an extinguisher would make a difference is very, very low.
2) I don't give a rats youknowwhat about what may or may not happen to my avionics if there were an in-flight fire.
3) The expected return on investment for the Halon is not that different from a lottery ticket.
4) There are other things I can / have done with a better $/safety improvement ratio.

Now, if I had a metric buttload of money lying around, then I might make a different choice. But I don't. So I didn't.
 
Halon inside the cockpit.

There is a brand of dry chemical extinguisher mixture called "Purple-K" (potassium bicarbonate):

https://en.wikipedia.org/wiki/Purple-K

Look at the extinguishers on the fuel truck and at the fuel pumps - they are probably Purple-K. Otherwise, for a hangar, you can look for a kitchen fire extinguisher. They generally are sodium bicarb (baking soda). These two chemicals normally remain powder, so they can be hosed off or blown/vacuumed out.

The other type of general purpose extinguishers normally use monoammonium phosphate that melts into a crust that chokes out the fire. That crust can flow into crevices and is very hard to remove, and very corrosive to aluminum.
 
Stewartb said:
Here's a pretty decent Halon Q&A narrative. See paragraph 5. An owner should have an idea of his extinguisher capacity relative to the cubic volume of the airplane. You can shoot enough to put out the fire and not threaten yourself. Especially since you can direct the Halon at the fire.

http://www.h3rcleanagents.com/support_faq_2.htm
Click to expand...

Actually, my hypoxia concern is not addressed in that FAQ. It's what they didn't say that people ought to know. Halon in concentration is a danger until it dissipates and may continue to be a danger afterwards. Ventilation is critical to safely discharging a halon fire extinguisher in a small aircraft cabin. Since halon is heavier than air, if you breathe enough into your lungs, you could continue to experience hypoxia effects even after changing out the air in the cabin.

This is probably a better study since it provides data and directly addresses halon in small aircraft. http://www.fire.tc.faa.gov/pdf/ct86-5.pdf. The FAA concludes that in the cockpit of a Cessna 210, a 2.5 lb halon fire extinguisher is safe and that levels never exceeded 6% at the pilot's face level...don't go sticking your head down looking for stuff. But it's important to note that they did this with a Cessna 210. The cabin volume is much larger that our average 4 seater airplane.

If you have to discharge a halon extinguisher in flight, open the vents and don't use the whole thing - 2.5 lbs will take 10-14 seconds to discharge. You might consider getting on oxygen if you have it...yes, I did just recommend oxygen in a fire situation.
 
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bflynn said:
Actually, my hypoxia concern is not addressed in that FAQ. It's what they didn't say that people ought to know. Halon in concentration is a danger until it dissipates and may continue to be a danger afterwards. Ventilation is critical to safely discharging a halon fire extinguisher in a small aircraft cabin. Since halon is heavier than air, if you breathe enough into your lungs, you could continue to experience hypoxia effects even after changing out the air in the cabin.

This is probably a better study since it provides data and directly addresses halon in small aircraft. http://www.fire.tc.faa.gov/pdf/ct86-5.pdf. The FAA concludes that in the cockpit of a Cessna 210, a 2.5 lb halon fire extinguisher is safe and that levels never exceeded 6% at the pilot's face level...don't go sticking your head down looking for stuff. But it's important to note that they did this with a Cessna 210. The cabin volume is much larger that our average 4 seater airplane.

If you have to discharge a halon extinguisher in flight, open the vents and don't use the whole thing - 2.5 lbs will take 10-14 seconds to discharge. You might consider getting on oxygen if you have it...yes, I did just recommend oxygen in a fire situation.
Click to expand...


Or just crack the door, that'll remove most of the halon in short order.
 
bflynn said:
Ok, I'm confused. I work in IT and have had Halon training. I remember a value of 7% dilution with air being the critical point where Halon will cause you to black out. Not immediately, but if you don't get into clean air quickly then you will die.

If I take a cockpit which we can generously say is 5'x5'x8' or 40 cubic feet x .0724 lbs/cuft3 (for air), I get 2.8lbs of air in that cockpit. If I discharge 5 lbs of halon into that then we're talking more halon than air and something around 60% dilution. Almost immediately that Halon is also going to start blocking the fire yes - and it will start blocking my lung's ability to process oxygen. I will immediately begin the process of suffocation. If I don't get air within about 2-3 minutes, the airplane will be minus one pilot...although in fairness I'll be dead before the airplane reaches the ground. Even if I get onto the ground, if I can't get the concentration out of my lungs, I'll die anyway.

I don't believe a halon extinguisher is reasonable in flight and might be worse than a fire. The fire might kill you, if you use a halon extinguisher in a small airplane cockpit and cannot get out then it WILL kill you.

Am I missing something?
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Your observations are completely inaccurate. A concentration of Halon 1211 sufficient to extinguish a fire in an enclosed area is nowhere close to lethality for humans.
 
3393RP said:
Your observations are completely inaccurate. A concentration of Halon 1211 sufficient to extinguish a fire in an enclosed area is nowhere close to lethality for humans.
Click to expand...

You state a true fact, but that wasn't my observation. It is that halon concentrations above the toxic levels can be achieved using a 5lb or even 2.5 lb halon fire extinguisher in a small cockpit such as a 172 or PA-28 and you may never know it until it's too late. Issues with halon are hypoxic and might persist after halon is cleared.

My observations and recommendations are:
1) Do not discharge the entire fire extinguisher. Use enough to get the fire out.
2) Sit upright in your seat, halon is heavier than air. Concentrations in the bottom half of the cabin will be toxic much longer than the upper half.
3) Open the vents. Not sure what this does in a PA-28 where the vents are on the floor, it might make things worse. I would like to see the FAA repeat the 1986 test with a PA-28, I don't think the results would be as rosy.
4) get on the ground quickly after an extinguisher discharge.
5) Consider using oxygen if you have it after an extinguisher discharge.
6) Fly an open cockpit airplane ;)
 
bflynn said:
You state a true fact, but that wasn't my observation. It is that halon concentrations above the toxic levels can be achieved using a 5lb or even 2.5 lb halon fire extinguisher in a small cockpit such as a 172 or PA-28 and you may never know it until it's too late. Issues with halon are hypoxic and might persist after halon is cleared.
Click to expand...

This assertion is what I was referring to. It is virtually impossible for Halon 1211 gaseous agent to reach lethality levels if a 2.5 lb. extinguisher is discharged in a typical GA cabin. The air exchange rate in the cabin will prevent to levels from reaching the toxicity threshold, and the normal ventilation air exchange rate limits the amount of time the gas is present in the cabin to less than one minute. Besides that, your description of a horrible death by Halon suffocation cannot be supported by the facts. It's just not that toxic.

My experiences with Halon 1301 and 1211, Halotron, FM-200, etc. span a career of over thirty years designing and building large data centers.

I suggest anyone interested in using a Halon 1211 read the NIST .pdf document linked below. It provides the information necessary to make an informed decision about carrying a Halon 1211 extinguisher.

For me, the advantages of using the Halon substantially outweigh those a dry chemical extinguisher, the main one being there is no damage to the aircraft. The Halon dissipates; the dry chemical residue is impossible to effectively clean up. There's no way to remove the aftereffects from the internal spaces behind the instrument panel, and the dry chemical agent is corrosive.

http://www.nist.gov/el/fire_research/upload/R0501597.pdf
 
That's funny, I've also spent a career in IT and have built data centers. I agree halon is a great choice for these installations. I'm not so convinced it'a great choice for smaller airplanes if the pilot doesn't understand it.

I disagree with you about levels. Did you read the FAA's 1986 report in which they discharged a 3 lb and 2.5 lb canister into the cabin of a cessna 210 located in a wind tunnel? In several tests the levels were above 7% for more than a minute. Yes, overhead air vents improve that as does the larger cockpit of the 210. Not discharging the entire fire extinguisher will also help.
In a smaller cockpit such as a 172 it will be worse by some unknown but significant factor and in an airplane such as a Piper with floor vents, venting the air may tend to stir the halons upward in higher concentrations.

Halon exposure creates hypoxia like effects of dizziness and loss of concentration and a very high dilution can cause damage to your nervous system and cause your heart to stop. Look it up, people have died from this and you know that. The first example I gave discharged a 5lb halon extinguisher into a small cockpit. The exposure level goes way over 7% - that is a lethal situation if you cannot clear the air out. Yes, as I said, that will be helped by venting and our airplanes tend to leak rather profusely too.

In a large commercial aircraft - great idea. If you want to carry one, I'm not your father and I'm not going to tell you that you can't. But be careful with them and understand that the gas can harm you.
 
Was that a 5lb extinguisher (about 2.5 lb of Halon), or 5 lb of Halon? I'm interested in reading about this.
 
The NIST report I linked references the 1986 FAA work. The FAA tests did not produce a level over 7% that "lasted several minutes". You're wrong in asserting that it did.

It says there has not been a documented case of Halon causing harm in an airplane in over twenty years. The report also clearly states the discharge in a Cessna 210 and a Cessna 421B cockpit did not exceed permissible LOAEL levels. In fact, the report says the discharge of a 6 lb. extinguisher would not exceed dangerous levels in either cockpit. There was no chance of the discharge producing lethal levels of gas concentration.

While it's obvious that a concentration of Halon over an certain amount of time can cause loss of consciousness and death, this will not happen when a 2.5 lb Halon 1211 extinguisher is discharged in a small GA cockpit.

That's the crux of the matter.
 
I have a 2.5 pound halon extinguisher in the airplane. I believe that I can hold my breath long enough to put the fire out and open the door.
The halon rig cost me $80, I could have gotten one cheaper, but I like the pretty polished stainless steel bottle.
 
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