Twin Set Diving

[JamieG]

Now as a few people know I have just returned to this diving lark after a bit of an absence, so I rejoined my old BSAC Club and besides other things most are using twin tanks.

I've only ever dived a single in the past and thats what I am doing to get back into the swing of things as its been a while since I got wet and don't want to over complicate things.

Anway, Most of the twins I've seen are not connected and run on two regs. This seems to be a superb Idea to me - Two 12L bottles each individual so plenty of redundancy with out the need to isolate either one if there is a problem - freeflow etc.

From what I've seen a lot of people dive twins with a manifold though - whats all that about then and why do some prefer it over the seperate twins set?

Thanks.

[SilvaFish]

I have 2 sets of regs on mine with manifold. If I develop a problem with one of my regs, for example, the one I'm breathing off decides to freeflow, I can shut that side down, and ensure that my manifold is open. That way, I have the gas from both tanks still available on my backup reg.

[Scuttler]

IMHO

Basically it simplifies the set up so that you don't have to keep alternating which cylinder you're breathing from.

If you have a failure on one cylinder (say a reg freeflowing) then you can shut that cylinder down and still have access to the gas in that cylinder via the manifold.

Finally if you're diving independants then you'll need 2 SPGs whereas manifolded twins only need one really.

[Madfish]

Have a look at the thread below, it should have been made a sticky IMVHO. There will be other threads, try searching for independents rather than twinsets and that will narrow down the search........

Twinset Advice

But don't be in a rush to follow your mates down the twinset route - take your time to get your skills & drills nailed again, then take a look @ twinsets if your diving/depth warrants it..

Good luck whatever.

Di

[Mark Chase]

In short twin independent 12s work well but add the task loading of switching cylinders every 50 bar. A manifold takes away this need but add the new problem of being able to isolate a cylinder if you have a problem.

I have dived both and slightly prefer a manifold but indis work fine.

ATB

Mark

[Paul Oliver]

Originally Posted by Madfish

Have a look at the thread below, it should have been made a sticky IMVHO. There will be other threads, try searching for independents rather than twinsets and that will narrow down the search........

Twinset Advice

But don't be in a rush to follow your mates down the twinset route - take your time to get your skills & drills nailed again, then take a look @ twinsets if your diving/depth warrants it..

Good luck whatever.

Di

Good advise and what a good post from Gareth

[Paul Oliver]

Jamie you will probably find that most of those twinset divers are either fashion victims or kit collectors but hey i could also be wrong and they could be doing the diving that warrents them if you are lucky

TBH i probably fall into the same category as all my 9 dives this year could have been done on a 15L and Pony + a 3L Deco stage on a couple The water has been too cold to do longer

[trakrat]

Originally Posted by Mark Chase

In short twin independent 12s work well but add the task loading of switching cylinders every 50 bar. A manifold takes away this need but add the new problem of being able to isolate a cylinder if you have a problem.

I have dived both and slightly prefer a manifold but indis work fine.

ATB

Mark

plus you don't have to keep taking your reg out to swop

[TerryH]

Originally Posted by trakrat

plus you don't have to keep taking your reg out to swop

Well yeah, but then again I dont have to spend hours in muddy puddles
playing with my knobs

[Richard Mason]

I had a crack on my recently acquired indies this weekend. It didn't seem that much of a drag and TBH, it gave me good reason to improve my situational awareness, vis a vis tank pressures and changing over regs is no big deal either.

Unfortunately (?) we don't have any diveable muddy puddles hereabouts, it's the briny or the pool.

I quite liked the simplicity of it all.

Just one issue that's struck me about using manifolds in this part of the world; the advantage as I see it is tyhat in the event of a freeflowing reg....burst hose, whatever, you can isolate the offending reg, turn off the affected post and then reopen the the affected post to access the air in the relevant tank again. This is all predicated on the UK/European configuration for cylinders which assumes failuire and air loss can only occur as a result of a regulator malfunction.

Down here, we have burst discs mandated, so a potential failure point before the reg. Now I've seen burst discs fail and it seems to normally occur when filling although I did have a slow leak for some time on a cylinder I bought here before I realised what it was, so I guess that could have gone anytime, in theory.

How does this potential failure point below the reg affect the manifold-isolator setup? I guess that it just meand that you cannot save the air in the affected tank. One would hope that a possibly narced diver wouldn't open his isolator once the roar of bubbles had stopped.