Re: [PSUBS-MAILIST] life support method?

["Alan D. Secor" <secor@btv.ibm.com>]

1.) When the absorbent is exposed to CO2, a chemical reaction occurs.  
The CO2 is "absorbed" and the absorbent gradually changes to chalk and 
produces H2O and heat as byproducts (that's why the air in a rebreather 
loop is warm and moist).

2.) If no supplemental O2 were added, the cabin pressure would gradually 
decrease due to the O2 in the air being metabolized by your body.  You 
are correct in assuming that if O2 were released into the cabin at the 
rate our body metabolized it, the system would remain fairly balanced.

3.) Partial pressures are really only relevant in a diving environment or 
an ambient pressure sub due to inert gas ongasing of the body's tissues 
and potential oxygen toxicity.  O2 toxicity does not become a problem in 
a 1 atm environment.

4.) Although there are several ways of providing O2 consistently, I think 
for the average p-subber the simplest way is with an O2 tank, regulator, 
and flowmeter as Vance suggested.


Al


>led me to several questions:
>
>1) Does the absorbant actually absorb CO2 and not return anything into the air?
>2) If not, does it just grab off the carbon atom and return O2, but just not at
>100% efficiency?
>It seems that if it absorbed CO2 only, and we simply added a little O2 every
>once in a while to compensate for the loss, then the system should stay
>balanced- but is this true, given a 1atm environment? (I don't know- I'm asking)
>
>3) Why does everybody watch partial pressures, and do we need to if the sub is a
>1atm environment? I assume it has to do with percentages changing as the
>pressure changes (in a typical diver/rebreather configuration), and thus they
>cannot rely on just percentage of O2.
>4) Can you get pure O2 from a consistent source without having to jump through
>hoops?
>
>-chris
>
>
>Alec Smyth wrote:
>
>>         Guys,
>>
>>         I can see the obvious merit of having an O2 sensor to know whether
>> the air you are breathing is good or bad. But why is it necessary to have it
>
>

--
Alan D. Secor
e-mail: secor@btv.ibm.com