Diving twins with manifold and isolator, but 1 reg?

[diversteve]

I actually think this is a very bad idea - plus they don't seem to update the site so it might just be a ghost but:

Welcome to TechnoDivers

 

[Bob DBF]

or go "old school" -

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That's my solution, however if I had to go out and buy one, I'd pick up the new manifold since it is relatively cheap and you don't have to do a rebuild to make sure it will function properly, not that there is much to an old manifold.

I actually think this is a bad idea - plus they don't seem to update the site so it might just be a ghost but:

Welcome to TechnoDivers

Looks like a new version of this.

I never look at a useful piece of equipment as a bad idea because someone could use it improperly. A motor vehicle could get you to a hospital quickly or run over a pedestrian, a society would try to make responsible drivers not ban the technology.


Bob

 

[beester]

I must be missing something here, but I've heard people say this before so I want to understand. How does a dive with a longer runtime inherently make redundancy important? The OP is in shallow water in the ocean and is making no-stop dives. It seems to me that a 120 minute reef bimble requires no more redundancy than a 45 minute reef bimble.

I've run into slight deco doing 50 ft dives on nitrox 32. But I digress... indeed if like the OP stated he only wants to extend his bottom time at that depth range, on a "reef bimble" there is no issue with redundancy.

 

[VaeVix]

or go "old school" -

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True story : a few days ago the french army released a recent picture of divers in a frozen lake, with wetsuits and only a left DS (therefore no buoyancy redundancy). I criticized the setup for being unsecure, especially as the guys were not clearance divers, more regular infantry guys doing SAR on the side. I found the manifold odd and I wondered how the posts were setup as I wasn't able to see the regs. It was exactly this model, which, given the better view is frightening...

 

[DevonDiver]

Putting the cylinders into an isolated manifold is a way of creating 'one big tank'. However, with only one 1st stage used, there are no benefits from redundancy. There are also hazards (hence the advice on blanking plugs).

To reap the true benefits of double tanks, it is a simple matter of buying a second 1st stage and splitting the 2nd stages on each regulator. You don't need an extra SPG, LPI.or different hoses.

It seems illogical to me that someone would suffer the expenses of banding/manifolding double tanks, but then fail to reap the total benefits of that for the relatively small cost of a second 1st stage.

Band and manifold the doubles. Add a second 1st stage. Split your primary and AAS 2nd stages on those two 1st stages. Dive it as per a single large tank - leave the isolation valve open. You do not need shutdown skills until you venture beyond recreational limits. You can learn these skills over time, whilst diving your 'big single tank'.

The other option is sidemount. I'm assuming that a second 1st stage will be obtained in either case. Balance the cost of bands/manifold versus buying a sidemount BCD, a 2nd SPG and a few hoses. If you will need a new BCD/wing to float/attach the doubles anyway then sidemount may prove cheaper.

If considering sidemount, then it's prudent to include the cost of training in the balance of calculations. Whilst it's possible to learn by yourself, it is far from optimal. Getting expert advice on sidemount set-up and configuration will fast-track you to comfort and enjoyment in the rig. Self-teaching can, for most divers, be a long and frustrating process. There are enough 'fine points' in diving sidemount to justify getting expert instruction.

Training for backmounted doubles is also prudent, but more divers seem to manage effect self-teaching with backmount. Backmount doubles isn't so fundamentally different from backmount singles, especially if you don't yet need to learn shut-down protocols. However, I'd counsel against experimenting with shut-down protocols without competent supervision - it's far to easy to make a mistake that'd leave you with no immediate gas supply.

 

[JohnnyC]

Since we're covering silly scenarios, might as well make it as safe as possible. Get one DIN valve, one LOLA valve, one connector whip. 2 tanks worth of gas with a single 1st stage. Silliness sorted.

At least then opening up the left post is by design and isn't going to shoot a plastic DIN plug past (hopefully) your head while simultaneously pissing gas at an accelerated rate.

The best answer is dive with a larger single, or get another 1st stage so you have the normal redundancy inherent diving two tanks.

 

[WarrenZ]

At least then opening up the left post is by design and isn't going to shoot a plastic DIN plug past (hopefully) your head while simultaneously pissing gas at an accelerated rate.

Please note anyone going with the DIN plug route use a metal gas saver plug "metal plug with o-ring" Those will stay in place even if the valve gets opened it will require a wrench to remove when there is gas pressure behind it.

Since I am clumsy I use them on all my tanks and have had to remove several after the valve got knocked open in transport much better to take time with a wrench to back out the plug then loose a $40 nitrox fill.

 

[rhwestfall]

there is also a plug with a relief screw available.Costly, but should a valve get bumped, it becomes real easy to deal with...

 

[dumpsterDiver]

or go "old school" -

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This is what the navy uses.. I think... This video shows a reserve on the manifold..

 

[John C. Ratliff]

Is there any way to dive a pair of aluminum 80's with a manifold such as this:

DGX Premium Dual-Outlet Manifold w/Isolator | Dive Gear Express®

but only use 1 set of regulators to breathe both tanks? Is this advisable? If not, why?

I am looking to prolong bottom time in shallow water (30-40 ft) on EAN/36 without having to dump my pair of tanks for a steel cylinder.

Thanks!

You might think about an older type of manifold. Two options have been discussed above. But there is a third, whcih I have used for over 30 years now.

Sherwood double scuba tank manifold
(Note: the text states: "Sherwood Stainless Steel yoke style manifold for double AL 80's with isolator valve. Used, but in excellent condition." But this is a brass manifold, not stainless steel. It also is not a isolation valve, as both cylinders feed off each of the posts independently.)

This Sherwood manifold allows the use of redundant regulators if you wish, but you can also dive a single regulator on either post, and pull air from both cylinders at the same time. This manifold is no longer manufactured, but this one on E-Bay looks to be a good buy.

Here I'm diving that manifold with a single regulator, which is a Mossback Mark 3 modifaciton to a U.S. Divers Company Aquamaster (which allows the use of an octopus and gauge).

Note that the dive computer has tangled with fishing line. Also, the second post has no regulator on it, but only a rubber stopper on it. I was diving fresh water, so getting salt water into the valve was not a concern.

Here, I have two regulators mounted:


I don't think you need reduntancy for diving 30-40 feet depths. I have been doing that for decades now. The surface is your redundancy, so if there's a problem, simply swim to the surface.

SeaRat