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Follow rule #1 ( Don't dive with strokes ), know your equipment, and be prepared for the worst; risk is minimized. On Sat, 25 Nov 1995, Jason Rogers wrote: > > > > I can be a bit of a bonehead as I seem unable to remember something. I would > > like to find out the following: has a manifold with or without crossover > > ever failed underwater? If so when, where and who? > > Two seperate manifold failures are documented in Martin Farr's book > "the darkness beckons" (as I remember). > > One was an isolation valve shearing off. The diver didn't die because > his entire gas supply vented in a couple of seconds, and formed an air bell > in a pocket above him. I understand that he waited there till his > companions returned. (Perhaps manifolds are ok if you only dive where > there are pockets in the roof?) > > The other one was in a lava tube. The diver was with Sheck Exley, but > I don't remember his name. He had a free flow (before reaching thirds) > and by the time he shut down the isolation valve, and the bad reg, he > had vented nearly 2000 psi from his doubles, leaving him with 300 psi. > > Apparently his RMV did not return to normal after his excitement, as, > despite the fact that this occured *before* reaching thirds, he totally > consumed Sheck's supply before they reached the staged gas. Fortunatly, > the staged gas was within sight, and the pair reached it by holding > their breath and swimming fast. The excitement wasn't over then! This > guy's RMV must still have been elevated, as he cosumed the whole stage > cylinder, dropped it and began buddy breathing the one that Sheck was > carrying. This time they used up all the air, and still couldn't see > the next stage bottles. Apparently they swam *very* fast, holding their > breath, and around the next corner, there were the stages. They then > reached the exit, with the remaining stage breathing hard and almost > out, with all the deco still to do. > > This guy then surfaced (the cave was 165 ft deep BTW) and there happened > to be someone there, and they happened to have a full scuba set in the > boot of their car, which they got, and dropped to the waiting divers. > > > It was my understanding that the concern over manifold failures is > > misplaced. Any tweaking of the high pressure seals in a manifold is likely > > to result in a problem that would be evident before the dive when the > > internal pressure of the system is at its greatest as would the torsional > > stresses to the rig. The real concern should be over simplicity of operation. > > > > > I'm not really offering an opinion since I don't know who tri-mix is ;-), > > but I do dive doubles with manifold (w/ crossover) and often solo. Hell, I > > swicthed from diving the doubles as independents because I thought my fears > > were misplaced (mechanical failures vs. ease of operations). > > > > Regards, John > > > > -- > > Send mail for the `techdiver' mailing list to `techdiver@terra.net'. > > Send subscription/archive requests to `techdiver-request@terra.net'. > > > > Cheers Jason =:) > > PS, Manifolds *do* make for some exciting stories don't they! > -- > Send mail for the `techdiver' mailing list to `techdiver@terra.net'. > Send subscription/archive requests to `techdiver-request@terra.net'. >
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