For 3,000 psi, in say, an AL80, you need 2241 psi 02, 759 air. Pushing it
with available 02 pressure, but close.

For 2640, you need 1972 psi 02, and 668 air. Possible with three cascaded 02
bottles.

80% was born of convenience, not logic. It was about as rich as you could
get with K bottle and compressed air for a top.

Scott


----- Original Message -----
From: "Kevin Connell" <kevin@nw*.co*>
To: "Brian McMillan" <bem@be*.ne*>; "Mike Rodriguez"
<mikey@ma*.co*>
Cc: <techdiver@aquanaut.com>
Sent: Thursday, March 23, 2000 7:32 AM
Subject: RE: 80% vs 100%


> At 11:34 AM 3/23/2000 +0000, stuart.morrison@sw*.co*.uk* wrote:
> >1. The oxygen-window is as open as possible with 100% O2 especially
> >    at the 20-foot stop.  Now you're gonna ask what the heck is
> >    an oxygen-window, right?  It's not a complicated subject, but I
> >    don't have time to do it justice now.  I get asked this all the
> >    time, so it's probably worthwhile to write something on it.  I'll
> >    do that in the next few days and email you a copy.  For now, let's
> >    just say that 100% O2 will allow you to off-gas faster then
> >    straight Buhlmann (and intuition) says you should.  In fairness, 80%
> >    does too, but it's disproportionately less efficient and has other
> >    important disadvantages.
>
>
> A little more on this:  You were too fair to 80%.  With any nitrogen (or
> helium) in the mix whatsoever, you need to decompress at shallower depths
> because (see mike's signature). Then, since we don't have time to explain,
> lets just say the oxygen window is the partial pressure of oxygen, and
that
> the higher the oxygen window, the faster or better the offgassing.  Given
> that, 20ft on oxygen is going to get you decompressed much faster than 80%
> at 30, MUCH MUCH faster than 80% at 20ft and MUCH MUCH MUCH faster than
80%
> at 10ft, where you are spending the majority of your time, anyway, if you
> choose strokemix.  This also reinforces why the majority of the oxygen
stop
> should be done as deep as possible despite what (see mike's signature)
says.
>
>
> ----------------------------------
>   Kevin Connell <kevin@nw*.co*>
>
>   NW Labor Systems, Inc
>   http://www.nwls.com
>
>   Res tantum valet quantum vendi potest.
>   (A thing is only worth what someone else
>    is willing to pay for it)
>
> ----------------------------------
>
> --
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