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>Peter wrote: > >This is not exactly rocket science. I can't believe that it adds greatly >to the cost, even meeting EU norms ;-) It does help in preventing some >channeling. How much do you pay for Sofnolime in the UK (it's made there I >think)? Actually I'm in Canada, so I can't comment on the cost of Sofnolime in the UK. However we payed (drum role please) $0.00 CDN for a 20kg pale. However shipping was about $100.00. The supplier gave it to us as a free sample and then shipped it express! Talking to others it sounds like the normal price for a $20 kg pale is about $130US. We still haven't finished off the first pale. >My point was that (1) at the surface you can crank the port down and >create a fully closed system (2) On a stationary bike you can almost >certainly exceed the capacity of the system to deliver O2 to the user if >he/she excercises hard, though this does depend on the mix being used and >the override will not kick in because there is probably not much change of >volume in the system (3) You can then calculate the exact VO2 for that >person (4) 1.0 ATA is the worst case scenario - but the safest when/if you >black out. You could also just use pure O2 and demand delivery. With some of our testing we just used the system in semiclosed mode and plumbed in an O2 sensor. This seemed to work quite reliably and is pretty easy to do with our breather. >> With pure O2 in shallow water I found that 0.8 l/m was about right for >> very very easy swimming (~200 meters/hour). At rest 0.8 l/m was too much >> and for any attempt to travel some distance ( ~2 km/hour) 0.8 l/m was >> not enough. > >How did you measure this? What rebreather were you using? Semi or fully >closed? I was using the breather fully closed with pure O2. It was equiped with a ~0.8 l/m constant mass flow valve. Unfortunately I didn't have the calibration equipment when I did this and hence the readings may be inaccurate. Anyway it is then easy to tell what your average metabolic rate is. If the system bubbles you're below 0.8 l/m if you need to use the bypass you're above 0.8 l/m. I swam about 1 mile underwater with the breather and had to constantly add O2 via the bypass. I then sat still in an attempt to photograph some fish and the system kept venting. On another occasion I made a circuit of a small rock. I moved very slowly looking into cracks in the rocks etc. and did not bubble and did not need to use the bypass. For pure O2 I think I would rather have demand addition than constant mass flow. This would prevent venting and would keep the system at the minimum FO2. >The Aladdin/Nemesis Nitrox doesn't >display your breathing parameter under water, so it's not going to be of >more use than the SPG. Well it would still help the coroner :). Barrie
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