<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi Willem, <div class=""><br class=""></div><div class="">thank you for your comments.<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 15. Nov 2021, at 08:18, Willem Ferguson via subsurface <<a href="mailto:subsurface@subsurface-divelog.org" class="">subsurface@subsurface-divelog.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class=""><blockquote type="cite" cite="mid:E6E2AB3C-4819-4287-8AAF-E4F47C9E0F71@atdotde.de" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><div class=""><br class="Apple-interchange-newline">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 style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">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 class=""></p></div></div></blockquote><div>Bailout is of course a special case. And yes, it should be handled dive segment by dive segment like an OC dive with several cylinders.</div><div><br class=""></div><div>PSCR is again a completely different thing. I would argue it’s closer to OC as the absolute consumption is also depth dependent. Are there any significant number of divers still using those? All I knew personally moved on to CCR. I don’t really know about how Subsurface handles the two types of cylinders for a CCR. Amongst those dives we use for testing is test40.xml which is a CCR dive with both an air diluent as well as oxygen cylinder and gas is used from both. I don’t know if that is typical. Do we have magic cylinder numbers like 0 that indicate diluent? I wasn’t aware of that.</div><br class=""><blockquote type="cite" class=""><div class=""><div class=""><blockquote type="cite" cite="mid:E6E2AB3C-4819-4287-8AAF-E4F47C9E0F71@atdotde.de" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><div class=""><br class=""></div><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=""></div></blockquote><p style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">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 class=""></p></div><br class="Apple-interchange-newline"></div></blockquote></div><br class=""></div><div class="">But what is the ratio of diluent use to O2 use? That test dive uses 123 liters of O2 and 100 liters of air.</div><div class=""><br class=""></div><div class="">Best</div><div class="">Robert</div></body></html>