Dan
Contributor
What is gas composition for typical 100m saturated dive? I just heard from the movie about using helium & oxygen mixture, but didn't hear about the % oxygen nor any nitrogen being used.
Last breath - hard hat story
- Thread starter Scared Silly
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Dan
Contributor
Never mind. I found the answer from Gas blending for scuba diving - Wikipedia
- "He/O2 12/88" would be a heliox blend with 12% oxygen and 88% helium. This gas would be used in commercial diving to depths up to about 100 metres (330 ft), depending on duration, but can not be used shallower than about 7 metres (23 ft) without risk of hypoxia.
Jay
Need to dive more!
At 6:29 (from the end) Chris L speculates "... high levels of oxygen carried in our emergence breathing gas ..." as for being a possible reason he survived.
I wonder what that meant, as in how high? 12/88 at that depth is a PPO2 of 1.32. If he was referencing high versus 12% ... I wonder how much higher and what PPO2.
uwxplorer
Contributor
3 computers died. HP, (or whoever built the triply redundant system) dare to explain?
Part 2, maybe...
Great documentary.
Part 2, maybe...
Great documentary.
In my experience, chamber atmosphere is typically +/- 0.3 ATA (PPO2) or 2.74% Oxygen at 100M/228'. The reason they don't shoot for .21 ATA, like on the surface, is there is less margin to the hypoxic limits in case of a gas emergency (pressure loss). Bell and diver breathing mix can go as high as .5-.8 ATA. The bell atmosphere tends to be a little higher because the volume is much smaller than a chamber so can change much faster.
The bell atmosphere is maintained using the same method as the chamber -- Oxygen is added as required to maintain the target PPO2 while CO2 is chemically absorbed. Virtually all sat dives are done on what is essentially as surface-based eCCR to recirculate the gas so the PPO2 is chosen for the working depth range, usually banked to the closest 1% mix. The diver's hat has a demand exhaust regulator and a hose that carries the gas to the surface where it is scrubbed, metabolized oxygen is added, and compressed into HP banks for reuse.
Bigeclipse
Contributor
Just finished watching it and wow. Crazy. I recommend people with it. It’s about a real life saturation dive which goes horribly wrong. I don’t want to ruin it for anyone but it’s a good documentary with some real life footage.
Watched it with a group of divers over the weekend and everyone enjoyed the movie. Great documentary.
I also wondered about the highly available system failing, but I've seen enough edge cases cause redundant electronic systems to not fail over properly to not but surprised.
I also wondered about the highly available system failing, but I've seen enough edge cases cause redundant electronic systems to not fail over properly to not but surprised.
Dang! I don't have Netflix. It sounds like something I would really like to watch.
Cheers -
Cheers -
Jay
Need to dive more!
free trial?
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