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#21
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How does a wet cloth really help (scientifically) to survive anairplane crash?
On Fri, 16 May 2014 07:48:32 -0400, micky wrote:
I'm pretty sure the amount of cyanide varies widely from one airplane fire to another, but there is no time to measure it. I agree that we don't have actual ppm levels documented yet, but, we do know that the hydrogen cyanide gas is deadly within minutes. One of the papers said death ensues within minutes. Another one discussed how a hundred people died, none of whom had traumatic injury, all of whom died from the toxicity of the gases in the fire. What we don't know is the ppm concentration REDUCTION that a wet towel provides us. |
#22
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How does a wet cloth really help (scientifically) to survive an airplane crash?
micky wrote:
So, what we really need is the key datapoint: a. What is the concentration of HCN in a typical aircraft fire? Who says there is a typical aircraft fire wrt HCN? Maybe we should use natural materials in airplane interiors. Understanding CO and HCN is especially crucial to today's fire service, because the smoke that firefighters were exposed to 20 or 30 years ago is not the same as it is today. Wood, cellulose, cotton, silk, wool, etc., were bad decades ago, but they were nowhere near as toxic as the chemically-manufactured materials of today. When combined in a fire situation, these chemicals are often referred to as "the breath from hell"2 and include compounds such as: a.. Acetyls-aerosol containers, combs, lighters and pens b.. Acrylics-glues, food packages and skylights c.. Nylons-various household containers, brushes, sewing thread and fishing line d.. Polyesters-hair dryers, computers and kitchen appliances e.. Polypropylene-bottles, diapers and furniture f.. Polyurethanes-shoes and cushions g.. Polyvinyl chlorides (PVC)-carpet, clothes, purses, records and shower curtains h.. Thermo sets-TVs, coatings, toilets, buttons, flooring and insulation http://www.firefighternation.com/art...more-dangerous |
#23
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How does a wet cloth really help (scientifically) to survive anairplane crash?
On Fri, 16 May 2014 06:51:56 -0700, Ann Marie Brest
wrote: ...snip... The other articles on cabin fires went into nice detail as to how hydrogen cyanide acts as a cellular asphyxiant by binding to mitochondrial cytochrome oxidase. They explicitly stated that smoke particles are not deadly in an airplane crash. So, what you, or I, would have assumed about smoke itself being deadly, is apparently wrong. If you still think your (and my) initial assumption is right, then what we need is an article about cabin fires which says both that the smoke particles are deadly, and, that a wet cloth reduces them. Otherwise, we're just making non-scientific assumptions. Was there any mention of the radiated heat from these fires? After personally experiencing a major fire in a building adjacent to our home, I learned to apprecaite that aspect. For certain, a wet cloth over the head would help shield. To see the potential shielding just envision sticking your head into a barbecue pit with, and without, the wet towel. The air into your lungs gets cooled so won't sear as much and at least your corneas should remain intact. |
#24
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How does a wet cloth really help (scientifically) to survivean airplane crash?
On 5/15/2014 11:26 PM, Ann Marie Brest wrote:
On Thu, 15 May 2014 20:16:19 -0400, Frank wrote: What's the wet cloth (scientifically) doing? http://www.faa.gov/pilots/safety/pil.../Smoke_Web.pdf That nicely summarized FAA article explains: - Smoke is a complex of particulate matter, invisible combustion gases & vapors suspended in the fire atmosphere. - Inhalation of toxic gases in smoke is the primary cause of fatalities - Carbon monoxide & hydrogen cyanide are the principal toxic combustion gases - Carbon monoxide combines with the hemoglobin in blood and interferes with the oxygen supply to tissues - Hydrogen cyanide inhibits oxygen utilization at the cellular level. - Carbon dioxide is a relatively innocuous fire gas, increases respiration rate causing an increase in the uptake of other combustion gases - Irritant gases, such as hydrogen chloride and acrolein, are generated from burning wire insulation - Generally, carbon dioxide levels increase while oxygen concentrations decrease during fires. And then finally, the article suggests: - Cloth held over the nose and mouth will provide protection from smoke particulates; - If the cloth is wet, it will also absorb most of the water-soluble gases (i.e., hydrogen cyanide & hydrogen chloride). What's interesting is that the entire article doesn't discuss any dangers of breathing smoke particulates, so, why it bothers to mention a dry cloth is perplexing since we can safely assume that filtering out particulates is merely a convenience, and not a safety issue. So, now we're left with the a WET cloth absorbing water-soluble gases. Of the two water-soluble gases, only hydrogen cyanide was listed in the article as being a safety issue (the other water-soluble gas was merely an irritant). So, I guess we finally have the answer to "why the wet cloth?". The WET CLOTH filters out (water soluble) hydrogen cyanide: "Hydrogen cyanide poisoning signs & symptoms are weakness, dizziness, headache, nausea, vomiting, coma, convulsions, & death. Death results from respiratory arrest. Hydrogen cyanide gas acts rapidly. Symptoms & death can both occur quickly." If I'm in a burning about to crash plane, I think the last thing I would worry about would be the smoke |
#25
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How does a wet cloth really help (scientifically) to survive an airplane crash?
On Fri, 16 May 2014 07:24:46 -0400, micky
wrote: On Thu, 15 May 2014 16:46:21 -0700, Ann Marie Brest wrote: I'm not sure WHERE to ask this, but, how does a wet cloth work in an airplane crash anyway? Why do they always boil water when a baby is coming? Something to keep the father occupied and out of the way. Do babies drink coffee? (on TV) In step 3 at 45 seconds into this video shows it in use: http://www.youtube.com/watch?v=RXaTt...etailpage#t=49 What's the wet cloth (scientifically) doing? |
#26
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How does a wet cloth really help (scientifically) to survive an airplane crash?
On Fri, 16 May 2014 08:05:39 -0700, RobertMacy wrote:
Was there any mention of the radiated heat from these fires? Yes. We noted that this flight safety PDF, which was all about protecting your airways in a cabin fire, explicitly said that the dry heat of a cabin fire isn't a major concern when it comes to protecting your breathing airways: http://flightsafety.org/download_fil...t06_p28-30.pdf As already noted, they said, verbatim: "the human body˘s upper airway naturally provides significant protection to the lower airway and lungs against extreme heat from hot, dry air." Absolutely none of the air-safety PDFs yet mentioned *anything* about the wet cloth having anything to do with cooling hot air, so, we can safely assume the only *safety* purpose of the wet cloth is to trap some of the hydrogen cyanide gas. |
#27
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How does a wet cloth really help (scientifically) to survive an airplane crash?
On Fri, 16 May 2014 08:05:39 -0700, RobertMacy wrote:
For certain, a wet cloth over the head would help shield. To see the potential shielding just envision sticking your head into a barbecue pit with, and without, the wet towel. The air into your lungs gets cooled so won't sear as much and at least your corneas should remain intact. I used to think that jumping up into the air when an elevator crashes to the ground, would stop me from crashing along with it. It's not supported by the facts. Neither is the theory that the wet cloth is there to protect us from the heat of the air during a cabin fire supported by *any* of the flight-safety references we have so far been able to find. Sounds good. I'd believe it myself, if I was just guessing. But, there's *nothing* in those flight-safety PDFs that says that the wet cloth protects against heat in a cabin fire. Now that's not to say that a cabin fire isn't *hot*. For example, this previously listed PDF shows the temperatures that can be reached in the cabin during a fuel-fed fire are extremely *HOT!*. http://wenku.baidu.com/view/8abb4621...fcc220e6f.html "In an aircraft accident that involves a fuel-fed fire, cabin air temperatures could be expected to reach 662 degrees F (350 degrees C) and higher. During inhalation, the air temperature might be reduced to between 360 degrees F and 302 degrees F (182 degrees C and 150 degrees C [respectively]) by the time the air reached the larynx" That article mentions that the wet cloth might filter out smoke particles (which don't seem to be an immediate danger), but it doesn't even hint at that wet cloth cooling down the air. So, unless someone comes up with a good reference, I think we can safely say that the *assumption* that the wet cloth is there to cool down the air breathed in a cabin fire is a false assumption (however good it seems to "sound" to most of us). |
#28
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How does a wet cloth really help (scientifically) to survive an airplane crash?
On Fri, 16 May 2014 05:50:29 -0700, RobertMacy
wrote: On Fri, 16 May 2014 04:24:46 -0700, micky wrote: ..snip.... Why do they always boil water when a baby is coming? Do babies drink coffee? (on TV) ...snip... LOL! just popped out for a spot of tea? However the heat from the hot water and towels dilates the cervix really fast, but does increase the risk of infection. Are you serious? (real question, no exasperation intended) They poured the hot water in her to dilate the cervix?????? What do they do when they're not in a farm house in 1920? Same thing? Years ago, newspapers were used too, because they were steam press rolled and sterilized, but not today. |
#29
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How does a wet cloth really help (scientifically) to survive an airplane crash?
On Fri, 16 May 2014 07:48:32 -0400, micky wrote:
It is frequenty reported that someone dies of smoke inhalation. It's frequently reported that people die of heartbreak also. And that Vikings wore horns on their helmets. And that Moses parted the water of the Red Sea. Or that George Washington had wooden teeth. Or that Benjamin Franklin publicly proposed the wild turkey be used (instead of the bald eagle) as the symbol of the US. Or that Napoleon Bonaparte was shorter than the average Frenchman of his time. etc. Lots of things are "frequently reported" and just as frequently untrue. That's why I had asked for "scientific" answers. Anyone can guess wrong. |
#30
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How does a wet cloth really help (scientifically) to survive an airplane crash?
On Fri, 16 May 2014 05:46:19 -0700 (PDT), trader_4 wrote:
As others have said, they focused on the main cause of deaths in fires and that is the gases. That doesn't mean that particles are not also dangerous and life threatening. Nothing I found, so far, says that the particles are life threatening. The HCN gas can kill you in a couple of minutes, for example. There was one reference which did say the wet cloth trapped particulate matter: http://wenku.baidu.com/view/8abb4621...fcc220e6f.html So, we can safetly assume that a wet cloth does trap particles, but, nobody has reported any real evidence that "smoke inhalation" (presumably that means particulate inhalation) is either immediately dangerous, or the *reason* for the wet cloth. Based on the evidence repoted to date, the reason for the wet rag seems to be to trap water soluble gases, of which HCN is the most dangerous in a cabin fire (according to all the references). |
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