2airishuman
Contributor
The dual-dip tube Beauchat Y-valves have been sort of a legend among solo divers. I've never seen any actually come up for sale, since I started diving.
Safe diving, particularly safe technical diving, is not solely an armchair intellectual exercise. Manifolded doubles are the gold standard for redundancy, not only because they make sense on paper, but also because they have better and longer track record for safety than any other SCUBA diving system, with millions of dives over around 40 years, and few if any serious accidents caused by failures of the manifold system.
Whether the isolator valve in a twinset overall improves safety is an equivalent question. The received wisdom is that it does -- neck o-ring failures, though rare, do occur, as do burst disc failures. There are also have been, though rare, situations where impact has damaged both a handwheel and a regulator.
One thing is clear, to me, though -- the Beauchat Y-valve is a huge improvement over H-valve arrangements, because the posts are better positioned, and because the gas paths are independent. I experimented with H-valves for solo diving, for a while, and came to the conclusion that they aren't useful.
Finally, with the declining availability of LP120 and HP149 cylinders, there are few dives where a Y valve is useful. I have a 72cf twinset (144 cf total) and find that there are few dives where it is useful. More often, dives that warrant redundancy call for a larger gas supply.
Safe diving, particularly safe technical diving, is not solely an armchair intellectual exercise. Manifolded doubles are the gold standard for redundancy, not only because they make sense on paper, but also because they have better and longer track record for safety than any other SCUBA diving system, with millions of dives over around 40 years, and few if any serious accidents caused by failures of the manifold system.
Whether the isolator valve in a twinset overall improves safety is an equivalent question. The received wisdom is that it does -- neck o-ring failures, though rare, do occur, as do burst disc failures. There are also have been, though rare, situations where impact has damaged both a handwheel and a regulator.
One thing is clear, to me, though -- the Beauchat Y-valve is a huge improvement over H-valve arrangements, because the posts are better positioned, and because the gas paths are independent. I experimented with H-valves for solo diving, for a while, and came to the conclusion that they aren't useful.
Finally, with the declining availability of LP120 and HP149 cylinders, there are few dives where a Y valve is useful. I have a 72cf twinset (144 cf total) and find that there are few dives where it is useful. More often, dives that warrant redundancy call for a larger gas supply.
