Rotating or Captured o-ring manifolds? Brand?

[jeraldjcook]

Any recommendations one which to buy, the rotating type or captured 0-ring type?

What are the advantages/disadvantages of each type? I've heard that if you want to carry the tanks by the isolator to make sure to buy the captured o-ring type? Is this true?

Lastly, what brand should I be looking at? My lds can order OMS and probably Genesis (the valves on all the singles in the shop)? Maybe more, but I'm not sure.

Thanks for the opinions.

 

[WD8CDH]

From an engineering standpoint, the captured o-ring face seal will seal better. The rotating type is more effected by manufacturing tolerances.

Technically, there should not be a differance between the two types as far as carrying the tanks by the manifold, but the only captured o-ring face seal manifold sold in the US IS bbilt stronger against bending than the available rotating type.

In my opinion, the only disadvantage of the captured o-ring face seal manifolds is lack of adjustability for center to center distance to match your bands.

Depending on the tanks you are using, some brands also make closer spaced manifolds if you want to make a more compact rig than the standard spacing but you would probably need custom bands or modified travel bands.

Personally, I have OMS, Thermo, Dive-Rite, ScubaPro and older Sherwood and UDS manifolds. Most of them have had their knobs replaced with OMS knobs if they origionally had larger knobs.

 

[skippy31]

The "captured" o-ring type manifold is advertised (or used to be advertised) as being just like a din fitting. The problem is that if you look at what happens on a din fitting is that you screw one into a valve and once seated nothing can move.

In the "captured" o-ring there is a swivel there too which means there is some play in the joint. They work fine, and people use them, but most divers used the barrel o-ring style manifold because it's adjustable and once threaded in the o-ring really does not see any stress.

They work so well that you can actually turn the isolator by hand when the system is under pressure not that I recommend that.

Mat.

 

[jeraldjcook]

The rotating type seem much more popular, just going by what I've gathered from posts.

I'd be concerned that I'd knock the isolator, something would happen where I would need to isolate one of the tanks, and the knobs isn't where I expect it to be. I've read you can lock the rotating style down to prevent this, but how does it make them different from the captured o-ring type (at least functionally)?

 

[skippy31]

Yes you can lock down the "rotating type" I prefer to call them barrel o-rings. There are lock nuts that allow the isolator to be fixed into position. If you hit the isolator hard enough though you may still be able to move it.

As mentioned one advantage of the barrel o-ring is adjust ability. because the threads are always engaged fully the o-rings really see no stress.

Because of the swivel the captured o-ring is not as rigid as a DIN fitting for example.

Anyway the choice is yours but in general I can tell you people prefer the barrel o-ring design.

Mat.