Y-pillars

[Mark Davies]

<font color='#000080'>I am currnetly shopping around and looking at options to introduce redundancy to my rig.

I didn't want to just add a pony to my 15l tanks because of the weight, so I have been considering two options:

1) Swap my 15's for 12's then add a pony,

2) Go to manifolded twin 7's.

The first option is clearly the cheapest of the two as I won't need to change any of the rest of my kit (so a couple of 12's costing £300, a 3 costing £100 and £65 for another first stage, £50 for an attachment system, less say £100 from selling my 15's - £415 all in).

I'd need to ditch my BCD and get a wing and harness to go with the twin 7 route, and that's looking at close to £1250 if I get two sets of twins (ouch!).

There appears to be no contest, but everyone that I've dived with who has twins can't seem to sing their praises enough in terms of trim and comfort when diving.

So I was thinking that twins was my prefered option - I was just going to have to decide to splash out.

However, while I've been going round the shops pricing it all up I've been shown a Y-valve type arrangement.

This is a valve for a single tank with two separate pillars that can be shut off separately, so that DV and octopus can be put onto separate first stages but run off the same tank.

This would appear to run in most respects much like a twin manifold ( ie in enabling the shut down of one first/second stage combination in the event of it's failure), except that it would not provide the option of isolating half the gas in one tank in the event of a failure of a connection between the bottle and the valve. The cost would be £45 for the actual valve (so 2 of those needed, one for each tank) and £65 for another first stage. Only £155!

However, I have NEVER seen them in use. Why is this? Are failures in the bottle/valve connection common? Are there other faults in the system?

My desire for redundancy has little to do with OOA situations. It seems to me that bad gas management is just that, whether you've got your air in one tank or two. I want redundancy to cover for equipment failure. It appears that this Y-valve covers all the angles except failure of the bottle/valve connection and I've never heard of this happening to anyone.

I'm sure someone knows better. Help me out, please.

Mark.

[Digger]

If the actual tank tot he valve goes, it just leaks a very small stream of bubbles, and you or your buddy should see it and get it looked at.

A good option that I saw was John Duncan, who had a single tank with a Y-valve, well, more of an H-valve, and screw the 2 1st stages in. Worked well changing between twins and singles, and has more redundancy than 2 2nd stages on 1 1st does.

Why not just buy a pony and use it with the 15s? You could sidemount it, so you're not carrying the weight around too much, and if your diving prgresses, as well it might, you can use it as a stage. Easy.

[Adrian Kelland]

A French couple in my club brought new cylinders with Y valves straight away. They made it sound very common in France, although I have only seen the single type in resort shops. Probably to avoid user confusion...

I am considering one for my own regs for when i don't want to use my twins, yet don't want to swap second stages etc onto one first stage.

Adrian

[steve-k]

<font color='#000080'>what i saw on friday was a tee piece adapter, it screwed directley into the tank valve, and had 2 din fittings

the downside would be that you dint have true independant first stages that you could turn off,
but on the upside you can use any tank, use it on holliday etc

imho
this is a better option, if your going to any reasonable depth where the redundancy is an issue thn you will be using your twins

steve

[Lawrence Debono]

I use an H valve on my single and it isn't the 1st time that I take a 4L pony down too.

In Y or H configuration if the 1st stage decides to be stupid, you can jump on to the other side. I also use twins etc. My main reason that I use redundancy is the temperature of our waters. You can be in certain areas of Lake Huron or Lake Ontario 20 or 30 meters deep and it would only be 3C - that's it. That is a recipe for free flow. So I want to play it safe.

I think an H or Y system is a great start.

Lawrence

[Phil Ennis]

<font color='#0000FF'>And of course an H valve is very DIR. &nbsp;

[Tibbs]

Originally Posted by [b

Quote[/b] (Phil Ennis @ Aug. 11 2003,20:32)]And of course an H valve is very DIR.  

You sure?

Chris

[Rob Evans]

Had a (Scubapro I think) H valve on my 15 for donks when I was on twins, apart from the safety considerations it made it a piece of cake to go from twins first dive to single second dive. &nbsp;Obviously the safety advantages go out the window if you can't get to the valves, and they were a little tricky in this respect. Best really to have a pony - inverted from personal choice. If I ever go back to OC (HA!) it'll be inverted all the way.

[Justin Owen]

Can you not get twin 7's on your BCD Mark? I'm currently in a similar fix, and am thinking of putting twin7's on my commando TD. Still agonising tho (thanks to a certain dive store that went back on their prices AND didn't have any stock after i travelled two hours to pick up a 7L twinset... grrr)

Pony for about £300 with a decent clamp and reg... Or twin7s, which I really fancy... But to do the same level of diving as I do now I'd need two 7L twinsets... Which with a latching system will cost me about £1000!!!! Ouch! Still, I've just had an endowment policy through... But it is meant to pay my loan off...... Must not spend *more* money on dive gear...

[Mark Davies]

<font color='#000080'>Justin,

I could attach twins onto my current BCD (an Oceanic Probe Kevlar) but it doesn't really give enough lift. So it will mean a replacement, and it might as well be a wing.

It seems that you're having much the same thoughts, and like myself just cringing at the potential expense. I dived with Nigel Waller last week - he was lucky enough to pick up two sets of used, manifolded twin 7's for £400 the pair! Just luck - right place at the right time. I'm keeping my eyes open for a similar opportunity - and now hoping that I get there before you do!

Everyone else, thanks for the advice. It seems like a viable option, so another element in the mix to add to the confusion. But I note that no-one seems to be currently using a Y-valve as a preference. However, given the relatively low outlay I'm thinking that it might be a useful stop-gap until I can get myself together to buy some twins. I'll have to try a little experimentation to see whether I'd be able to get to the valves for a shut-down.

Cheers team - you've come good yet again!

Now, if anyone has any ideas where Justin and I can pick up some great value twin 7's ... ?