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Re: [PSUBS-MAILIST] Sgt. Peppers O2 consumption rate question.
----- Original Message -----
From: <SFreihof@aol.com>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, November 29, 2000 6:16 AM
Subject: Re: [PSUBS-MAILIST] Sgt. Peppers O2 consumption rate question.
> Just a few notes on the subject...
>
> O2 consumption is mostly dependent on workload and/or stress. Carsten's
> figure of 1/2 liter per minute is for a person at rest. Under exertion,
> consumption can rise as high as 2 liters/minute.
Yep.
>
> Breathing is affected most by elevated carbon dioxide levels (partial
> pressure CO2 up to 0.05 atm) not by low oxygen levels. The discomfort
you
> feel after 45 minutes in your unreplenished sub is not low oxygen, but
high
> carbon dioxide.
Yep. My understanding is that CO2 triggers the "breathe reflex", which is
why when there's too much of it, we start breathing harder and harder. I
experienced a lot of this back when I was experimenting with simple
'inverted bell" rebreather bottles. There's still oxygen in the mix, but
you feel like you are suffocating, and you breathe with extreme distress.
All things equal, I'd rather have my scrubber outlast my
> oxygen because I would rather go from low 02 (sleepy) than high CO2
> (suffocating).
I know some of us agree on that, but let's talk about this for a second. I
know there's a doctor in this group; can't remember whether it was Snyder or
Nugent; but one of you guys who works in medicine might be able to answer
this. Let's say we're in a pressure hull under the conditions Stan
describes above: we run out of O2 before the scrubber quits. What's it
going to be like? Is it going to be like "shallow water blackout"
experienced by some skin divers, where they are cooking along one moment,
and then just conk out; or is there going to be some indication of the onset
of unconsciousness: possibly, the "sleepy" condition mentioned above?
I think this would be something anyone operating a LSS in a dry sub should
understand, so he can know what to look out for in the event his system
starts to fail due to lack of oxygen. OK Doc: what symptoms accompany the
onset of oxygen deprivation prior to unconsciousness? Wouldn't it be about
the same as hypoxia experienced at altitude without supplemental O2: a kind
of drunkeness, and possibly a reckless, giddy euphoria? Or, if the O2
bottle goes dry unexpectedly while the scrubber's still working, will I just
zap out with no prior warning?
Pat