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<div class="moz-cite-prefix">On 2021/11/15 00:07, Robert Helling via
subsurface wrote:<br>
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<blockquote type="cite"
cite="mid:E6E2AB3C-4819-4287-8AAF-E4F47C9E0F71@atdotde.de">
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Hi Poltsi,<br class="">
<div><br class="">
<blockquote type="cite" class="">
<div class="">On 14. Nov 2021, at 22:44, Paul-Erik Törrönen
via subsurface <<a
href="mailto:subsurface@subsurface-divelog.org" class=""
moz-do-not-send="true">subsurface@subsurface-divelog.org</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class=""><span style="caret-color: rgb(0, 0, 0);
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!important;" class="">When CCR, you're mainly interested
in the consumption of O2 as noted previously. The diluent
is not really telling since it is mainly a function of
your profile as you use diluent to equalize the pressure
in the loop. A serrated profile (lot's of ups and down) ==
large volume of diluent used because of addition to loop
when going down, then dumping it when ascending.</span><br
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<div>I can see that the amount of O2 used divided by total dive
time could be of interest. But it’s definitely something else
than SAC and thus should not be mixed with it. For example, in
any statistics when you have both CCR and OC dives, it would
make zero sense to combine the two. So even if we computed
this number, it should not be displayed as SAC or stored as
such. Let alone the number with an ambient pressure correction
like the SAC makes zero sense for a CCR.</div>
<br class="">
<blockquote type="cite" class="">
<div class=""><br style="caret-color: rgb(0, 0, 0);
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<span style="caret-color: rgb(0, 0, 0); font-family:
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!important;" class="">Of course this also happens to O2
also, but what would be interesting to see is how/when
your consumption of O2 changes due to increased work.</span><br
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<br class="">
<div class="">I meant more the other way around: If you diluent
also contains O2, you underestimate the O2 consumption if you
only use the pressure drop in the O2 cylinder.</div>
</blockquote>
<p>The O2 consumption under CCR is not a dive characteristic because
the diver can bail out to OC. So O2-consumption would be a
cylinder-level characteristic, associated with cylinder 0 ?? (i.e.
the diluent cylinder because as far as I can remember the O2
cylinder does not explicitly exist in the Subsurface CCR dive
log). In pSCR bailout is often part of the normal dive procedure
during deco.<br>
</p>
<blockquote type="cite"
cite="mid:E6E2AB3C-4819-4287-8AAF-E4F47C9E0F71@atdotde.de">
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<div class="">So here is a question I have: For a typical CCR
dive, what is the ratio between used O2 and used diluent? I
understand this depends on how often descend and how often you
flush but what is a ballpark type figure?</div>
<div class=""><br class="">
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</blockquote>
<p>As a ball park approximation, many CCR dives (up to 65m) are done
using air as a diluent, supplemented with oxygen from the O2
cylinder to make up for oxygen consumed as well as for higher O2
levels during shallower deco.<br>
</p>
<p>Kind regards,</p>
<p>Willem</p>
<p><br>
</p>
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