Diving with two tanks

[Sponon]

Is it possible to connect the two tanks and only use one regulator or do you need separate regulators, one for each tank?

OK, so you need two regs, do you use an alternate air source/octopus (four 2nd stages)?

Hehe, you guys must be banging your heads in the wall when reading this...

 

[Blackwood]

Is it possible to connect the two tanks and only use one regulator or do you need separate regulators, one for each tank?

Yes, you can connect two tanks to one first stage.

OK, so you need two regs, do you use an alternate air source/octopus (four 2nd stages)?

No, I don't have four second stages.

Hehe, you guys must be banging your heads in the wall when reading this...

Yes. Ouch.

 

[LeadTurn_SD]

Currently, the most common configurations for diving with two tanks (doubles) are:

1. Manifolded doubles: The two tanks are connected by a "manifold", and most commonly now an isolator valve on the manifold; two regulators are used.

2. Independant doubles: The two tanks are not connected; two regulators are used.

3. Sidemount: Similar to Independant Doubles, but the tanks are worn/slung on the diver's sides rather than on the back. Two regulators.

You only use two 2nd stages, no "octo" as with a conventional rec setup. Typically, one is on a long hose, and is the one you donate to an out-of-air diver, the other is on a short hose and bungied beneath your chin.

Best wishes.

 

[DaleC]

Not a bad question if you do not know.

The first manifolds (the thing that connects the tanks) were single outlet (allowing one first stage). This was because divers were using doublehose regulators and did not generally have back up regulators. They only wanted more gas and only needed one outlet.
As time went by, the singlehose (first stage/second stage) regulator system came into being. After awhile manifolds were developed to allow two first stages which added a level of redundancy to the system and also allowed for isolation and preservation of gas if a failure occured (if an isolator valve was used). With two first stages the common practice is to use only two second stages in total (one on each first stage).

I'm sure someone can provide some examples of double outlet manifolds being available early on but I think this is roughly the timeline for single outlet/double outlet manifold development.

 

[Sponon]

Thanks guys

 

[captain]

Example of a single outlet double manifold

 

[Gilldiver]

I'm sure someone can provide some examples of double outlet manifolds being available early on but I think this is roughly the timeline for single outlet/double outlet manifold development.

The first 2 post manifold that became common was the Sherwood in the early 1970's:

The center post was retained so that it could be used with the double hose regs. The first two post manifold, that I remember, with both posts over the tanks was the Sherwood Genissis manifold which was used with the first 3500 psi steel tanks. These came out in about 1988/89 or so.

 

[DaleC]

Thanks Pete. That was exactly the type of manifold I had in mind when I said there was something between the single outlet and modern isolation styles. And Captain... why do your old tanks look nicer than my new ones

 

[captain]

Or you can fab up one like this.

 

[vjanelle]

There's also pig tail manifolds, which will connect the two tanks together, but in the event of an oring failure you'll lose ALL your gas since there's no isolator.