Some question about doubles

[nimoh]

great information here, one thing I would add is that the manifold crossover is a potential failure point as well.

If the failure is on one of the two connections to the tank valve, then closing the crossover will save half the gas (on the side that doesn't have the leak). If the failure is on the crossover valve o-ring, then closing the crossover will save the gas in the right side only. These are pretty rare situations though, but is commonly used as an argument for independent doubles.

This is only true for manifolds that I have seen, there are probably manifolds out there that are opposite, or that work entirely differently. I am under the impression that the manifolds I have dealt with are the most common...but I have been wrong before

 

[TSandM]

Somebody ran a thread a few years back, either on the Deco Stop or the Cave Diver's forum, asking if anyone had had a tank o-ring or manifold failure, and as I recall one or two people had HEARD of someone having such a failure, but no one on the forum had actually seen one themselves.


Of all the dives I have done in doubles, and in the community in which I dive, where most people dive them all the time, I have never heard of a failure that required isolating. In fact, failures in general are rather rare, but when they do occur, they are more typically leaking wing inflator, dry suit inflators, or leaking second stages.

 

[Bob Sherwood]

I actually had a student break a manifold underwater. They shut done the post, and it still was leaking and they isolated and it still was leaking. I told them it was broke and we ascended to surface non event. Then they wanted to go to shore and fix it. I told them, it's broken for real non fixable. Funny he said yeah I know, but......gonna go try. Laughing. The manifold literally split and gas was coming form thee split. I have it on video somewhere. As said here these things are a rare occurrence but it was cool to see

Somebody ran a thread a few years back, either on the Deco Stop or the Cave Diver's forum, asking if anyone had had a tank o-ring or manifold failure, and as I recall one or two people had HEARD of someone having such a failure, but no one on the forum had actually seen one themselves.


Of all the dives I have done in doubles, and in the community in which I dive, where most people dive them all the time, I have never heard of a failure that required isolating. In fact, failures in general are rather rare, but when they do occur, they are more typically leaking wing inflator, dry suit inflators, or leaking second stages.

 

[PfcAJ]

Broke from impact on something? Id love to see the video!

 

[Bob Sherwood]

Yes he hit something. It was pretty funny at the time. We were pretty shallow and he was in disbelief that it was really broken.

Broke from impact on something? Id love to see the video!

 

[TSandM]

Was there a scooter involved?

 

[Bob Sherwood]

Oddly not. Swimming. Hit the manifold on stable object and must have hit it just right. Failure was not catastrophic, just a constant slow steady leak until empty.

Was there a scooter involved?