building up double tank setup, how difficult? DIY or take them to LDS

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eelnoraa

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I have all the parts (I think): 2 LP80, bands and manifold. How difficult is it to put them together? Is it a DIY or should I have a shop do it? If DIY, is there any trick or things I should pay attention to?
 
The main concern is keeping the manifold cross bar lose at all times. To insure that it is one needs to keep the cylinders parallel at all times. As you screw it in and as said in the video make sure the threads engage both valves. As you continue to screw it realign the cylinders so they remain parallel. The cross bar in the video seem to have way more play in it than I have found with my manifolds.
 
It is not difficult but you need to be careful you dont cross thread the valves.

You also technically may need to have new visuals done on your tanks because there will be no pressure in them. (You can solve this by using a whip and adding a little bit of pressure back into the tanks if you have one)

The video tecrec posted is helpful. ScubaToys also has video which is pretty much the ssame thing.

Twins, Dual Scuba Tank Assembly of Twin Tanks - YouTube
 
Easy if you know what you are doing. I think the videos would give you a good indication of what to do. You could also ask your potential tec instructor to help you. Generally speaking tec instructors are passionate about diving and would be eager to transfer knowledge if they can get a new student.
 
As others have mentioned, it's not hard IF you know what you're doing. Best to do it the first time with someone experienced. You *could* easily ruin the manifold if you're not careful.
 
Which is easier to cross thread the fine 18 x 1 threads on a isolator bar, or the 3/4 x 14 coarse thread on the tank valve?

What I do for building up dub's

1) Assemble *just* the tanks and the bands, no valves at all. Snug up the bands nice and tight

2) Assemble the manifold.

3) Compare the center to center distance of the tanks and the manifold. If they are not the same either adjust the manifold (if possible) so they are, or *stop* and figure out why. Wrong manifold, wrong bands etc.

4) Loosen the bands and slide one tank down ~4-5inches.

5) Without disassembling the manifold screw one tank valve into one tank.

6) Slide the other tank up and engage the second valve.

7) Spin the tank to screw on the second valve. A large strap wrench helps.

8) Position the bands at 11" apart, with the upper band as high on the tanks as possible (at the "break")

9) Snug up the bands and check that the iso bar (barrel oring type) can still turn with minimum effort

10) Gas them up a bit ~500-1000 psi and check for leaks

11) Fill fully and check for leaks.

This method is much much easier than trying to start two fine threads at the same time while keeping two heavy scuba tanks perfectly parallel.

Tobin
 
The are easy to do, there is a lot on info on the web. You should be fine to do it yourself
 
https://www.shearwater.com/products/swift/

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