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Re: [PSUBS-MAILIST] pressure hull sizing
I think you are confusing oxygen toxicity and nitrogen narcosis. The
symptoms you describe are due to nitrogen narcosis. CNS O2 toxicity can
occur at a much shallower depth and is a function of time and partial
pressure of O2 at depth. For instance at 20 ft, pure O2 has a partial
pressure of 1.6 atm and max exposure is 45 min. After that, you risk O2
toxicity which is much more serious than nitrogen narcosis. O2 toxicity
can cause convulsions and loss of consciousness which can result in
danger of drowning if on scuba.
In a 1 atm sub, the PPO2 is only .21 (same that we are breathing now)
and therefore O2 toxicity is not a concern.
Al
rjune@fuse.net wrote:
>
> Just a quick caution note.
> *CAUTION*
> If you are using pure O2 you can experience O2 poisoning.
> Or if you are using a pressurized hull, where the internal
> pressure equals the water pressure at depth, and pressurized
> air, O2 poisoning can occur around 100 to 120 feet.
> O2 poisoning in itself is not dangerous, but a person affected
> by O2 poisoning will tend to do stupid or un-rationale things
> that result in death. For example a diver might think that he can
> breath without his regulator.
> >
> > From: Al Secor <wreckdiver@usadatanet.net>
> > Date: 2002/05/05 Sun PM 09:11:23 EDT
> > To: personal_submersibles@psubs.org
> > Subject: Re: [PSUBS-MAILIST] pressure hull sizing
> >
> > This has been covered before in the list archives. You input O2 at the
> > rate your body metabolizes it...somewhere between .8 and 1.0 liters per
> > min at rest. You circulate the cabin air through a CO2 scrubber which
> > extracts the CO2 from the air. As a result there should be no net
> > increase or decrease in cabin pressure and it remains at 1 atm. A
> > simple baramoter can be used to keep track of the cabin air creeping up
> > or down. A valve to vent the cabin environment to the outside at the
> > surface will equalize and small pressure differential to avoid any
> > difficulties in opening the main hatch.
> >
> > Al
> >
> > DBACKIDS@aol.com wrote:
> > >
> > > It seems that whether you put the excess air into a tank, or vent it
> > > (which seems a better idea), you will still need a pump, because as
> > > Adam said, the surrounding pressure also increases. A valve would only
> > > equalize the pressure, would it not?
> >
> > --
> > Al Secor ARS: WA3PWX Scuba Instructor SSI DCSI #5528 TDI #1413
> > http://www.geocities.com/SubDiverI
> >
--
Al Secor ARS: WA3PWX Scuba Instructor SSI DCSI #5528 TDI #1413
http://www.geocities.com/SubDiverI