Hi Willem, thank you for your comments.
> On 15. Nov 2021, at 08:18, Willem Ferguson via subsurface > <[email protected]> wrote: > >> >> 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. > 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. > 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. 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. >> >> 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? >> > 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. > > But what is the ratio of diluent use to O2 use? That test dive uses 123 liters of O2 and 100 liters of air. Best Robert
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