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

["Paul B" <paul_victor@hotmail.com>]

Hi,

>So actually, a tank holding 10 cubic feet of O2 at 1ATM lasts longer (in
>theory) at 160 feet?
>Carl

I'm sorry, but what are we comparing it with?

If we're talking ambient pressure subs..

The problem is, you can't breathe pure O2 for long periods of time, 
especially at high pressure. Same goes for breathing gas with high partial 
pressure of O2 (That includes air at 200ft+). It will painfully kill you, 
destroying your lungs, the more the pressure, the faster.

The key is to maintain appropriate partial pressure of O2. Ideally - within 
0.18-0.40 (if I remember the diving manual correctly). That's why they make 
different mixtures with different O2 percentage, depending on the depth of 
your operations. With regular air, 200 ft is pretty much the limit (partial 
pressure of O2 gets too high and you get nitrogen narcosis), and I wouldn't 
even recommend going that deep with it. Helium/oxygen and proper equipment 
may take you as deep as 600 ft. Any deeper — you're talking BIG BUCKS.

Sincerely, Paul.

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