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Re: [PSUBS-MAILIST] Question about pressure compensation



Partial Pressure means that the pressure a gas contributes to the total pressure is in direct relation to its proportion of the total gasses....
 
I don't know if I said that well.  Let me give an example...
 
Air is 80% nitrogen, 20% oxygen.  So, at the surface, nitrogen contributes 80% of 1 atm pressure (or 0.8 atm), and the oxygen contributes 20%, (or 0.2 atm), for a total of 1 atm between the two.
 
So, at 5 atm (132 feet depth, saltwater) the partial pressure of oxygen in air is 1 atm (0.2 x 5 atm) .  That's the same as pure oxygen (100%) at the surface (1 atm). 
 
Did I just make mud of it?
 
Stan
 
 
In a message dated 1/18/2005 4:09:22 P.M. Eastern Standard Time, thijs-struijs@planet.nl writes:
Bill and the rest,
 
Pressure compensation of battery pods and trusters with air seems the most simple and clean way to do it i think. It also has the advantage that you don't have to put a square battery in a bulky round box. But in a discussion on this subject a view years ago Michael Wludarczyk wrote that at higher pressure (300 psi / 200 mtr.)  the partial pressure of the oxygen (PPO2) becomes so high that there is a substantial fire risk. This is of course a lethal depth for an ambient sub but i want to go to 100 mtr. in an 1 atm. sub. Eigther i missed something during my schooldays or i simply forgot but PPO2 doesn't mean anything to me.  Is there someone on the list who can say something sensible about this?
 
Thanks,
 
Thijs Struijs
The Netherlands