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<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.
 

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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.
 

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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
 

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<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
 

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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
 

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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.  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.
 

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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...
 

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<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 ... ?
 

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[b said:
Quote[/b] (Mark Davies @ Aug. 11 2003,23:52)]

Now, if anyone has any ideas where Justin and I can pick up some great value twin 7's ... ?
Twin 7 300 bar £310.

Go Dive

Daz,

(umm tempting...)
 

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[b said:
Quote[/b] ]I could attach twins onto my current BCD (an Oceanic Probe Kevlar) but it doesn't really give enough lift
Ehhh???

If you can put a single 15 on it, it can certainly handle twin 7s! They're smaller and lighter!
 

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This actually happened so I can't be 'done' for anything as I see it...

After seeing the excellent prices that Go Dive had on their website, I emailed them to see if they'd do me a deal on either two 7L twinsets or a twinset + pony for the missus - i gave them the best prices i had so far and asked what they could do. I got an email back saying "yes we can do better prices, but you're trying to start a dutch auction and we don't get involved in such things".

Irate, I rang up and asked how i could 'starting an auction' when i'd simply asked for there best prices. Silence was the reply. So again, now over the phone, I asked for the price he could do me a twinset for, with MDE valves, single cylinder boots, and stainless bands... 'The price on the website' (£299) was the reply - 'and does that include stainless bands?' i asked. 'Yes' came the reply.

So, I take a day off work, travel up to meet Digger (thanks Digger by the way - haven't had chance to email you yet) who kindly had offered to show me his twin7 setup and come with us as he also needed some equipment and we we're gonna try and get a deal on the lot.

After making a list with their sales guy, we were almost ready to go. £299 for the twinset. Then, no MDE valves in stock. Will be the following week and they'll have to post them so £15 carriage. Great I thought, but still almost ready to hand them the card. Then, hold on a minute - he wanders off and comes back and say's they can't do the twinset at that price. It'll be another £50 for the MDE valves plus the £15 delivery. Now we're only a few quid cheaper than everyone else.

As I point out the conversation I had earlier in the week a voice pipes up and says "When I said £299 with bands you get Sanosub valves..." Said guy then wanders off again.

Disgusted I go off to get a drink with missus and Digger in tow.

Needless to say I didn't buy anything for myself as I was well peeved.

To be fair though, the missus got her Pony with ATX40 for a very good price - seems no one can touch them on Apeks stuff.

But I wasn't impressed - if I do go twin7's i'll be going back to SDS. Yes it'll cost be another £20 or so, but they are worth it in my opinion.
 

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If you get a SOS manifold, the valves will almost certainly be stiff to turn when the cylinders are full.

Take it to Runneymede to get them O2 cleaned, and they'll come back revolving perfectly smooth at all pressures.

I was considering replacing my manifold not long ago for that one reason, but am no longer fussed. SOS is fine by me.
 

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<font color='#000080'>
[b said:
Quote[/b] (Dominic @ Aug. 12 2003,08:04)]
[b said:
Quote[/b] ]I could attach twins onto my current BCD (an Oceanic Probe Kevlar) but it doesn't really give enough lift
Ehhh???

If you can put a single 15 on it, it can certainly handle twin 7s! They're smaller and lighter!
Dom,

It doesn't really give enough lift for my 15 either, but I've persevered with it. I've simply decided that if I'm making such a radical change to my set up and spending so much on it, I might as well get it right.
 

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<font color='#000080'>Got two valves and an Apex DS4 on order.

Hopefully I'll have them fitted, tried and tested and run through some shut-down drills in time for going to Mull. I'll report back on how it works out.

If anyone else is interested I sourced the valves via Beaver at £43 each. So for £175 (including the new first stage) I've adapted two simple, single cylinders to provide me with redundancy and have a reg set-up that can be fitted directly to a set of twins when I get them.

This way I can buy the twin rig piecemeal. First a harness and wing to be used with my singles. Once I've got used to using that (and saved some more money) I can buy the first set of twins. Of course I can still carry on using one of the singles for a second dive because the regs will swap straight over without any adjustment! In time I'll get a second set of twins.

I can spread the cost over time and I can change to a new system in stages, learning each element seperately as I go along.

It seems like such an elegant solution, I'm surprised that I've not seen it in use before.

I for one am a happy bunny. I've got the redundancy that I wanted with no extra weight and for no more than the cost of a pony.

Result!
 

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<font color='#000080'>Now then, the valves arrived and we got them fitted. Tried it out with the tank in the upright position and even in jeans and T-shirt I couldn't reach the valves for a shut down!

So, inverted it is. Long hoses on order.

I'm going to need some protectors for the valves so that I don't damage them when kitting / de-kitting in a seated position. I've seen that Custom Divers do a solid looking protector for a single cylinder, but they sell for around £50 each! (That's more than the valves!).

Does anybody know of an alternative that doesn't cost as much? Or perhaps someone that could knock something together for me?
 

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<font color='#000080'>Thanks for that, Daz. They'll do nicely.

I tried out your suggestions for the hose routeing and found that the current hose on the alternate was fine as it was if passed under the arm. In fact, I've got a swivel on my main DV already and might try that under-arm first; I'll just have to see how it works when donated. I am going to bring the BCD hose up my back and over the shoulder though, so need a slightly longer one.

It's going to be a fairly unique set-up; maybe it will catch on?

(Doubt it!)

Mark.
 

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Mark,

Nice neat setup by the sounds of it,  definitely not common but it achieves redundancy and makes it easy to switch from a single to twin setup.   Nice bit of lateral thinking.

I have the double version of that valve guard and am pretty pleased with it.

If it does catch on, you realise we will have to refer to it as an "Inverted Markarthian Rig"  


Daz
 
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