On 17/05/14 08:28, John S wrote:
On 5/16/2014 12:00 PM, Frank wrote:
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

If you are the driver and can't see through the smoke, would you worry
about the smoke then or relax and resign yourself to your fate?

I believe you meant to type 'pilot' and I'd be doing everything within
my power to fly the aircraft and survive