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How does a wet cloth really help (scientifically) to survive an airplane crash?



 
 
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  #21  
Old May 16th 14, 03:18 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
Ann Marie Brest
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Posts: 35
Default 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  
Old May 16th 14, 03:23 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
Bob F
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Default 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  
Old May 16th 14, 04:05 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
RobertMacy
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Default 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  
Old May 16th 14, 06:00 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
Frank[_16_]
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Default 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  
Old May 16th 14, 06:01 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
[email protected]
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Default 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  
Old May 16th 14, 06:34 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
Ann Marie Brest
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Default 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  
Old May 16th 14, 06:42 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
Ann Marie Brest
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Posts: 35
Default 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  
Old May 16th 14, 06:46 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
micky
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Default 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  
Old May 16th 14, 06:50 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
Ann Marie Brest
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Posts: 35
Default 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  
Old May 16th 14, 06:54 PM posted to alt.home.repair,sci.electronics.design,rec.aviation.piloting
Ann Marie Brest
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Posts: 35
Default 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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