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I'm pretty sure the amount of cyanide varies widely from one airplane
fire to another, but there is no time to measure it. as I understand it the HCN is produced when plastics containing nitrogen burn in an oxygen poor environment. Stuff like synthetic rubber upholstery, pulyurethane foam insulation and and melamine tray-tables As I understand it, this is akin to the major reason you're supposed to get out of a computer room if the Halon extinguishers are triggered. The Halon itself isn't particularly hazardous (at the concentrations used in these systems), but the combustion byproducts from burning plastics and etc. are really nasty. The Halon suppresses some of the flame reactions and stops the fire, but it doesn't get rid of the poisonous partially-combusted plastics and other decomposed flammables. |
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On 5/17/2014 5:39 AM, Kurt Ullman wrote:
As I understand it, this is akin to the major reason you're supposed to get out of a computer room if the Halon extinguishers are triggered. The Halon itself isn't particularly hazardous (at the concentrations used in these systems), but the combustion byproducts from burning plastics and etc. are really nasty. The Halon suppresses some of the flame reactions and stops the fire, but it doesn't get rid of the poisonous partially-combusted plastics and other decomposed flammables. The reason you want to get heck out of a Halon environment is that is displaces the oxygen so you have nothing to breathe. (It works on the "air" part of the old fire triangle). I've taken some fire training courses. Halon is low enough levels, that one can remain in the room. I've seen movies of a test dump. The guy looked a bit frieked out but was OK at the end of the movie. There were some system using carbon dioxide, and those displace oxygen. Halon works on the fourth side of the triangle, sustained chemical reaction. Actually fire tetrahedron. -- .. Christopher A. Young Learn about Jesus www.lds.org .. |
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In article ,
Stormin Mormon wrote: I've taken some fire training courses. Halon is low enough levels, that one can remain in the room. I've seen movies of a test dump. The guy looked a bit frieked out but was OK at the end of the movie. Price I pay for relying on 30+ year old memories. Halon works on the fourth side of the triangle, sustained chemical reaction. Actually fire tetrahedron. One of my mentors suggested a fire pentahedron. fuel, heat, oxidation material, chemical reaction, and Chief Officers. You take any one away and the fire goes out. -- łStatistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.˛ ‹ Aaron Levenstein |
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On Sat, 17 May 2014 06:53:49 -0400, Stormin Mormon wrote:
There were some system using carbon dioxide, and those displace oxygen. Halon works on the fourth side of the triangle, sustained chemical reaction. Actually fire tetrahedron. Thank you Stormin' Mormon, for explaining that the proposed supposition that halon displaced oxygen was not supported in the literature. I found a similar explanation to yours in this FAA book on aircraft Fire Protection Systems: https://www.faa.gov/regulations_poli...a/ama_Ch17.pdf It's pretty troubling that some people believe stuff that has absolutely zero references in the literature that backs up their claims. I'm glad you're not one of them! |
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On 5/17/2014 12:22 PM, Ann Marie Brest wrote:
On Sat, 17 May 2014 06:53:49 -0400, Stormin Mormon wrote: There were some system using carbon dioxide, and those displace oxygen. Halon works on the fourth side of the triangle, sustained chemical reaction. Actually fire tetrahedron. Thank you Stormin' Mormon, for explaining that the proposed supposition that halon displaced oxygen was not supported in the literature. I found a similar explanation to yours in this FAA book on aircraft Fire Protection Systems: https://www.faa.gov/regulations_poli...a/ama_Ch17.pdf It's pretty troubling that some people believe stuff that has absolutely zero references in the literature that backs up their claims. I'm glad you're not one of them! As I remember from my fire protection courses, that (not displacing oxygen) was one of the advantages of halon. Of course, the government found it to be ozone toxic and outlawed it. Put that on the list of "if it works, outlaw it" along with DDT and machine guns. -- .. Christopher A. Young Learn about Jesus www.lds.org .. |
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On Sat, 17 May 2014 15:21:15 -0700, Stormin Mormon
wrote: ...snip.... As I remember from my fire protection courses, that (not displacing oxygen) was one of the advantages of halon. Of course, the government found it to be ozone toxic and outlawed it. Put that on the list of "if it works, outlaw it" along with DDT and machine guns. Yes, but *if* you already have the extinguisher, you're allowed to refill it! So I bought three. One for kitchen, one for the car, and one for the electronic lab. |
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On Sat, 17 May 2014 05:39:45 -0400, Kurt Ullman wrote:
The reason you want to get heck out of a Halon environment is that is displaces the oxygen so you have nothing to breathe. (It works on the "air" part of the old fire triangle). Hmmmmmm... isn't that the *opposite* of how Halon works in a fire? I tried to find an airplane cabin fire article that backed you up. For example, this was the first hit: http://www.h3raviation.com/news_avoiding_mayday.htm But, all that article said was that the carbon monoxide from the aircraft cabin fire would displace the oxygen. And, specifically, it said that halon does *not* "displace the oxygen" which is how carbon dioxide extinguishers work. Here's what the article said, verbatim (in part) about the benefits: --------------------------------- Halon is an effective agent on Class B and C fires, the ones you're most likely to see in an aircraft. It works in gas form, so it will not obscure your vision like the powder emitted from dry chemical extinguishers. Basically, it's invisible. As a gas, it's capable of getting into hard-to-reach places like the inner workings of your instrument panel. It's a non-corrosive clean agent, which means it won't damage items it comes into contact with. It won't shock-cool your avionics. It's lighter and more efficient than CO2. Halons are low-toxicity, chemically stable compounds. Sounds perfect, right? Well, there are a few drawbacks. We said that Halon has low toxicity. But it's not benign or entirely non-toxic, and you wouldn't want to introduce it to your respiratory system given the choice. "But everyone, including the FAA, recognizes that it's better to put out the fire effectively than to worry about breathing the Halon," |
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In article ,
Ann Marie Brest wrote: On Sat, 17 May 2014 05:39:45 -0400, Kurt Ullman wrote: The reason you want to get heck out of a Halon environment is that is displaces the oxygen so you have nothing to breathe. (It works on the "air" part of the old fire triangle). Hmmmmmm... isn't that the *opposite* of how Halon works in a fire? Yep. As I mentioned I was trying to go with 30 year old memories. That, and I never did inspections.... -- “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” — Aaron Levenstein |
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On 5/17/2014 12:19 PM, Ann Marie Brest wrote:
On Sat, 17 May 2014 05:39:45 -0400, Kurt Ullman wrote: The reason you want to get heck out of a Halon environment is that is displaces the oxygen so you have nothing to breathe. (It works on the "air" part of the old fire triangle). And, specifically, it said that halon does *not* "displace the oxygen" which is how carbon dioxide extinguishers work. At least that part of my memory works. -- .. Christopher A. Young Learn about Jesus www.lds.org .. |
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