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On Fri, 10 Jun 1994 ddoolett@me*.ad*.ed*.au* wrote: > I want to comment on the breathing supply redundancy from the > point of view of a cave diver. I believe Dan Nafe's comment > stressing the primacy of the dual outlet manifold is simplistic > and rather, I agree with Richard Pyle that one must design a rig > that is appropriate to the type of diving. No diving equipment > of any sort fills every need. Here in Australia the standard > cave diving breathing setup is a minimim of two independent > cylinders either back or side mounted. I believe that this is > the optimum system for overhead enviroment despite the increase > in task loading. You should reduce your task loading in other > ways (diving within your comfort zone etc.) rather than by > reducing your equipment redundancy. Here we do alot of solo, > long penetration diving, and only completely independent gas > supplies are appropriate. I do not believe that a solo diver > would have much luck operating an isolating manifold. on the contrary... in IANTD upper level classes the isolation manifold is required equipment *AND* the students train on and become *VERY* comfortable with operating them by themselves in the pool *BEFORE* going to the open ocean with the equipment. On the > other hand, for deep diving in a situation where you can dive > with a buddy and are not too far from stage bottles, I think > that manifold tanks are ideal. Where there is considerable > narcosis, the task loading of monitoring independent supplies > can be a problem, if the diver cannot deal with mutiple tasks under narcosis, including manifold switches, then this diver should *NOT* be in that situation. again, if the diver cannot deal with the tasks of what ever equipment it takes to be safe (this means totally redundant), then that diver should go back to class and practice until the time comes that he or she is proficient at management of such. (this is speaking of any "technical dive"). aloha, dennis pierce the speed with which gas is used at depths is > a problem in a single cylinder, and additionally you should > continuously have the regulator in your mouth (or full face mask). > > By the way I know of someone who had both blowout disks rupture > (tanks overpressured) wat the beginning of the dive. > > In regard to Richard's mention of using two different mixes > in independent tanks, I realize this may be a necessity in > some deep diving in open water, but this was the cause of > death in an Australian wreck diver recently (see Greg Ryan's > post on the subject), who inadvertantly used his 50/50 nitrox > at 47 metres depth. > > David Doolette > ddoolett@me*.ad*.ed*.au* > -- > Send mail for the `techdiver' mailing list to `techdiver@opal.com'. > Send subscription/archive requests to `techdiver-request@opal.com'. >
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