Re: [PSUBS-MAILIST] New means having alot to learn.

[Coalbunny <coalbunny@onewest.net>]

Why is it breathable only below those depths?
Carl


Paul B wrote:
> 
> Hi,
> 
> >BTW, is it possible to "prep" for a dive by placing yourself in a
> >zero-nitrogen environment?  If so, how?
> >Carl
> 
> It's possible to use helium/oxygen breathing gas mixture. However, you will
> _still_have_to_decompress_ (only now it will be helium, that's dissolved in
> your tissues, not nitrogen).
> 
> There are other advantages and disadvantages to helium/oxygen mixture:
> 
> The main advantage is that you are free from nitrogen narcosis (feels like
> being drunk, that can happen at deep dives)
> 
> BUT:
> 
> -Helium has higher heat conductivity than nitrogen. You can get mighty cold
> mighty quick.
> -Helium/oxygen mixture is _expensive_
> -You will sound like Donald Duck because of lower gas density. It can impair
> communication.
> 
> For VERY deep dives they use hydrogen/oxygen mixture. Hydrogen/oxygen
> mixture is explosive and can ignite at a smallest spark (static electricity,
> for example). So they have to make it inert, by putting very little oxygen
> in it (3% — compare to 20% oxygen in regular air). Therefore, this mixture
> is only breathable below 150-160 feet, when partial pressure of oxygen rises
> to breathable limit.
> 
> Advantages and disadvantages of hydrogen/oxygen mixture are pretty much the
> same as with helium/oxygen plus the fact it's only breathable at 160 feet
> and deeper.
> 
> Hope this helps.
> 
> Sincerely, Paul.
> 
> _________________________________________________________________
> Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp

-- 
"The plain meaning of the right of the people to keep arms is that it is
an individual, rather than a collective, right and is not limited to
keeping arms while engaged in active military service or as a member of
a select militia such as the National Guard." - U.S. vs. Emerson, 5th
Circuit Federal Court- published October 16, 2001