[PSUBS-MAILIST] L.S.S.-Life Support System

[MerlinSub@t-online.de (Carsten Standfuss)]

And this loss of pressure can open an automatic barometric oxygen-vale..
..very simple control. Self-leveling. But not undepentable of the
temperation of the cabin air. 

Better is also to meassure the PO2 pressure in the cabin. And maybe the
PCo2.  

I have a question for all - in the "Seehund" world war two two man
submarines they use the oxygen-flow from the oxygen pressure bottle via
a injector nozzel (venturi nozzel with side entrance) to flow the cabin
air (in mixture with the oxygen) to pass the scrubber. No fan. My
impression is that this can not work because the oxygen flow is to low -
but obviously some of the boats stay two days underwater.. Any idears
how to calculate or explain how it works ? 

regards Carsten

Ian Roxborough schrieb:
> 
> The scubber (CO2 absorbent) will reduce the air pressure in the
> pressure vessel as it absorbs CO2 (carbon dioxide) from the air.
> I think this is the loss of pressure which Peter is talking about.
> 
> Ian.
> 
> On Mon, 13 Dec 2004 22:00:26 -0800
> "Rick and Marcia" <empiricus@telus.net> wrote:
> 
> > >> An altimeter shows the pressure lost as
> > >> carbon dioxide is consumed, oxygen is added to bring the cabin pressure
> > >> back.
> >
> > Hi, Peter . . . in what way is carbon dioxide consumed?  And why would
> > pressure be lost?  And, is this a closed system we are talking about?  A
> > one-at boat?
> >
> > CO2 is generated, not consumed, as a waste product of O2 metabolism in the
> > body.  Oxygen is added, not "to bring cabin pressure back", but, rather, to
> > keep the occupants alive.  In a closed system, the cabin pressure has
> > nowhere to go - there is simply an EXCHANGE of gases from atmospheric air (~
> > 80 % N2, 20% O2).  That means a gradual INCREASE in cabin pressure.
> >
> > Cabin pressure remains the same regardless of whether the inside air is
> > being consumed by passionate lovemaking, smoking a cigar or burning
> > electrical insulation.
> >
> > If pressure relief was all that was required, nitrogen would suffice.
> >
> > >> They open an equalizing valve after surfacing before opening the
> > >> dome.
> >
> > That's to equalize the addition of  oxygen (that had previously been stored
> > as a compressed gas in cylinders) to the cockpit. There is a gradual
> > increase in cabin pressure over time from compressed O2 entering from the
> > bottles into the cabin.
> >
> > The occupants generate CO2 that gets reduced by the scrubber fans drawing
> > the CO2 across racks of Baralyme.  The lungs soak up the O2.  Interesting
> > things happen when mammals breathe high concentrations of CO2 and O2. Hence,
> > the scrubbers.
> >
> > The body has cells called chemo-receptors that determine when to breathe.
> > These receptors are sensitive to both O2 depletion and a blood increase of
> > CO2.  These are referred to as blood gases.
> >
> > The theoretical maximum saturation of oxygen in the blood runs somewhere
> > around 99%.  This can vary according to the concentration of O2 in ambient
> > air, efficiency of the lungs, whether the O2 is displaced from the red blood
> > cells by CO, etc.  Many factors determine blood gas levels including drugs,
> > altitude and more.
> >
> >
> > Rick Lucertini
> > Vancouver, Canada
> >
> >
> >
> >
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