Y or not to Y (Valve)?

[Foggy]

I'm after your thoughts....I am switching my kit config over for twin use, which doesn't really accomodate singles (changing hoses and plugs between dives, and as the reason was redundancy why compromise),but limited funds only allowed one twinset (12's) so should I get a Y or H valve for my aging singles (15lt & 12lt dumpy), or use them for decanting?

The former option probably gives more gas, and the opportunity of having a different premixed gas, but less true redundancy. BUT where can one get these valves and how much do they cost? Anyone using them?

Cheers, Paul

[tom]

Paul,

I use an H valve on my single, as do a few others on here - for me the main reason is to enable me to swap easily between twin and single rigs as you say. My valve is made/distributed by Beaver, and was ordered through the LDS. Think it cost about £40-£50. There's some more on this thread:

http://www.yorkshire-divers.co.uk/fo...t=valve+beaver

Whether its worth doing it or not depends very much on whether you ever intend to dive a singles rig again (I like to use one for shallow shore dives etc). If out on a boat for a two-dive day, I've found that I almost invariably end up with more gas for the second dive by decanting into the twins rather than switching to the single (15l).

[Foggy]

Originally Posted by tom

I use an H valve on my single, as do a few others on here - for me the main reason is to enable me to swap easily between twin and single rigs as you say. My valve is made/distributed by Beaver, and was ordered through the LDS. Think it cost about £40-£50. There's some more on this thread:

http://www.yorkshire-divers.co.uk/fo...t=valve+beaver

Spot on, many thanks for that Tom

Originally Posted by tom

I've found that I almost invariably end up with more gas for the second dive by decanting into the twins rather than switching to the single (15l).

But doesn't that screw up the mix if you've got a richer Nitrox for your second dive?

Cheers Paul

[Darren A]

I tried to get one of these for my single, but was told by SDS that they were no longer legal.

[Fathoms Down]

Originally Posted by Foggy

But doesn't that screw up the mix if you've got a richer Nitrox for your second dive?

It can do so you have a choice; either work out what you need in the filling cylinder, drain the twins to the needed tank pressure and them top them or (what I tend to do) dive on the resultant mix and feed the new O2 level into the computer.

[tom]

Originally Posted by Foggy

But doesn't that screw up the mix if you've got a richer Nitrox for your second dive?

Yep, unless you've got exactly the same mix in both sets (e.g. air). I take an analyser on the boat so I know exactly what I end up with in the twinset.

For the (fairly standard, shallowish recreactional type) diving I do I'm more concerned about having the best mix for the first dive rather than the second. The second dive tends to be a shallow drift where extending no-deco times isn't usually a consideration (my buddies are often on air anyway, so we end up running an air schedule with me using nitrox for conservatism). The main thing I consider to be a potential issue is exceeding MOD, so I just make sure there's no way the mix I end up with can be too rich for the second dive.

This is obviously a compromise but it seems to work for me. If you want to make sure you've got the optimal mix then as you imply separate sets are the way to go. Depends on the kind of diving you are doing I suppose.

[NotDeadYet]

Remember you will need to factor in the cost of a decanting hose. AP do one, about £80 IIRC with a button gauge or anything up to £500 for a really good one with a digital gauge. Or you can do this or this if you have an old spare MDE manifold. I'm not a fan of decanting, you will get condensation in the donor bottle which you need to keep an eye on.

Depends how much you will use singles. You may find that when you start twinset diving you rarely use them again. Give it a month or two and see what you think.

If you get stuck for them then Decathlon sell H valves as most of their kit is French and they are more common over there.

Cheers,

Stuart

[Mark Davies]

I think I might have started a trend for H-valves on YD when I fitted them last year. Quite a few people have seen them on trips and taken them up.

There's more to it than being able to swap easily with a twin-set. I almost always dive with my single 15's. I look at each individual dive and if the dive doesn't require a twin-set full of air then I don't use one. The reason I got the H-valves was more to introduce similar redundancy to twins with my single tanks. It gives me the option to shut down a free-flowing regulator. Pair that with an air integrated computer that won't let me accidently run out of air and I feel comfortable enough to dispose of a pony. It makes my rig much less cumbersome.

So, to answer your question, even without the issue about swapping to twins I think they're worth having.

[NotDeadYet]

I agree. I don't dive singles at all and haven't for about 9 or 10 years. If I was going to I'd use an H valve rather than a pony, it's a much cleaner set-up. A pony is just a crutch for bad technique.

[BJ]

I swapped twin 7s for a single 15 with an H-valve (MDE) about 15 years ago and never looked back. Perfect for single-mix OC diving.