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Mark Welzel wrote: > If you blow a tank neck oring or a burst disk you then HAVE TO > isolate the regs AND switch regs. On independants you would > only HAVE TO switch regs. > > As long as you managed your regulator switches and your gas in > each tank properly you will not have a problem with independants > any more than you will have a problem with a manifold. I still > prefer a manifold but do dive independants occasionally. A lurking stroke has to comment... Looking at all of the arguments, the manifold seems safer in almost all of the scenarios; but the "safety" margin appears to be salvaging the gas in both cylinders in the event of a tank-valve or beyond (1st stage, 2nd stage, tank O-ring, etc) failure of one tank. You close the tank valve and keep your gas. This is a good thing <tm>. The danger in independents is, alas, they are "independent". Something screws up and you've kissed the failing tank's gas goodbye. Or horror upon horrors, you blow the manifold valve's O-ring and lose both tanks; but that ain't supposed to happen, is it? Or more likely you have to close the manifold valve, leaving you a single. I seem to hear (though I may be wrong; be gentle, George) that manifold divers "sort of, kinda, almost" count on gas in both tanks. The ones arguing for independents stay, well, "independent". Granted the probability of failure (free-flow, 2nd stage, hose, 1st stage, tank O-ring, etc) leans toward the manifold to save the otherwise lost gas, have there ever been "manifold" failures? Can it fail in a mode that would let gas escape from the valve? I fully realize and respect the value of isolating a [rare] tank failure by closing the valve, and even further appreciate the value of salvaging the gas in the failed side otherwise; but if that little sucker in the middle bites the big one you're losing both tanks and kissing the big one. Sounds like betting that one valve against the other possibilities. I'm aware of the other possibilities; how about that sucker in the middle? But back on track - do you manifold divers "count on" both cylinders for gas supply at all times? I'm reasonably certain that you don't, but you're jumping on the independent guys since they're "stuck with one tank" while you say you "have both tanks". Most likely true (I really do see the point, sounds really good) but how sure are you that you do have both tanks? I haven't heard of any tales of manifold valve antics to know. Is the manifold valve that foolproof? If so, I have no further doubts. But if not, you're dead if it fails, no? Do you have another alternate supply? I know the odds are in your favor, but the manifold has always seemed like a single catastrophic point-of-failure to me. Asbestos drysuit donned, fire away... Jeff Kell <jeff-kell@ut*.ed*>
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