UWS: Isolater valves VS Dual-Valve Mflds

[JE]

In Jeffrey Bozanic's latest issue of Cave Diving Accidents 2002-2005 he relates his issues concerning the above named manifolds. In his analysis, he states that " he feels that the Dual-Valve manifold has a much cleaner & nearly accident free history of usage"-! Using both of these manifolds on my back-mounted doubles, I can back up what Jeffrey says about which is safer to use-! In short, with the current Isolater manifolds being marketed, I along with a number of other cave divers have experienced 'roll-offs' in varying degrees of threatening situations-! I don't trust the Isolater- valve set-up the way I do the dual-valve manifold. I hope everyone here gets to read this excellent issue of the CDS's 'Accidents Review'-! It has an abundence of helpful information allowing us to hopefully become more aware of our diving excursions & the equipment that we choose to use-!

Jack E. 8)

[DeWayne]

If you experienced a roll off, then you definitely need to improve upon situation awareness. Neither system will offer safety from not following procedures and maintaining a keen sense of awareness. Even with the valves that only require a turn or two from open to close, it takes much more than just a casual scrape against the ceiling to shut them down.

[JE]

If you experienced a roll off, then you definitely need to improve upon situation awareness. Neither system will offer safety from not following procedures and maintaining a keen sense of awareness. Even with the valves that only require a turn or two from open to close, it takes much more than just a casual scrape against the ceiling to shut them down.

Dewayne,

Jeffrey referrences an 'auto-shut off' on one or the other side of the tanks when either your forward movement is fast enough {ie...scooter powered} or when brushed against a ceiling or wall, involveing this isolater mfld. The only thing that happens when using a dual-valve mfld while making this same swim is that you may damage the karst or the rubber/plastic knobs. My swimming attitude & plane is such that I very rarely, if ever brush a wall or ceiling, {when in a practiced diving state} I have never experienced an out of air situation, except while diving my isolater valve last summer inside the Catacombs at Ginnie. That one roll-off scared the daylights out of me-! I don't trust the isolater valve the way I do the dual valve Mfld-! I do appreciate your thoughts though.... thank you. I'm only giving my own opinions on this subject.
Dive safe & good hearing from you

Jack

[DeWayne]

All the isolator does is give you an option to isolate your gas supply should there be some catastrophic event such as a burst disk or tank neck o-ring blowing. While such events are indeed rare, should they happen in a non-isolated manifold setup, you stand to loose all of your back gas. Jeff's observations seem to be based on available stats that include for the most part, user error. You just cannot produce a sound argument for or against this unless you can isolate the incidents to only those involving equipment malfunction. So we are left to analyze for ourselves and make a best guess decision based upon what we each perceive as an accetable amount of risk versus safety. I do not fear shearing off the isolator as I do not believe in scootering through tight spots. Whenever I swim through tight spots I make a routine of constantly checking my valves to ensure that they are open. Thus for me, the isolator does afford an out for a possible situation that might occur without imposing any additional risk factor. I always check the isolator valve prior to as well as after filling to ensure that it is open before entering the water; I am also somewhat anal about analyzing the gas in my cylinders. Such procedures rule out the majority of the accidnets that the argument against isolation are made from. Regardless of which system is dove, it will not be safe unless some strict procedure is adopted and adhered to on each and every dive.

[JLH]

I am new to cave diving, only 30 dives I've heard of left post roll off's of course. But how do you get a roll off on an isolator valve?

Jack

[D1V3R]

I dont see how its even possible to roll off, unless your using one of those DIN valves that are shaped like a capital T