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

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

Hi, Carl

>Why is it breathable only below those depths?
>Carl

Because 3% of oxygen at normal atmosphere pressure is too little for humans 
to breathe. As you go deeper, the pressure rises, so partial pressure 
(pressure, created by one single gas in a gas mixture) of oxygen rises, and 
the mixture becomes breathable.

Let's see if I can explain it by numbers:

For example, air consists of 78% nitrogen, 21% oxygen, and some odd percent 
argon, helium, etc.

O2 21% @ 1 atm = 0.21 atm partial pressure (that's O2 in regular air, 
breatheable)

In hydrogen/oxygen mixture:

O2 3% @ 1 atm = 0.03 atm partial pressure (which is not enough to breathe)
O2 3% @ 6 atm (approx. pressure at 160 feet) ~ 0.18 atm O2 partial pressure 
(that's enough to breathe)

See, you have more oxygen in the mixture at this depth, so you can breathe.

Sincerely, Paul.

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