Single Cylinder - twin valves, why?

[Phil_C]

Ok - probably a silly question, I have been looking at cylinders for sale and have come across quite a few single tanks advertised with twin valves fitted. What if anything is the benefit of twin valves and why would you do it on a single tank other than redundancy?

Cheers P

 

[flyandive]

Ok - probably a silly question, I have been looking at cylinders for sale and have come across quite a few single tanks advertised with twin valves fitted. What if anything is the benefit of twin valves and why would you do it on a single tank other than redundancy?

Cheers P

H-Valves?
It would be for redundancy. Can't think of any other reason. Instead of having one first stage regulator with two second stages you would have two first stages and two second stages. In case of a first stage failure you would still have a complete backup.

The cons would be cost and that if you have more failure points (O-Rings) then you have greater chances of failure. The difference is whether or not that failure would cause you to lose your ability to breathe. Could be very important in overhead diving (Cave or Decompression).

 

[Phil_C]

One company I am looking at sell each tank size in both configuration - single and double valves, double valves are about £60 dearer than single valves. I thought it must be redundancy. P

 

[aquaregia]

It's for prevention as well as recovery.

When sharing air, the two breathers will be getting air from different first stages. If both divers were on the same first stage, there would be an increased change of freeze-up while air sharing, which would likely leave you with zero gas for the pair. Even if the divers cannot shut down a freeflowing valve properly/in-time, this (to me) makes dual outlet valves worthwhile.

 

[Tortuga68]

Also, so you can use your doubles regs without having to reconfigure them for a single tank/valve

 

[ScubaBB]

It's cheaper then a double-bottleset and saver then just one valve.

 

[Bob DBF]

It may not be an H-valve, there is a valve that each air path is completely seperate, including seperate dip tubes. I ran across it when looking into Y and H-valves but can't for the life of me remember where, and I'm too lazy to look again.


Bob
-----------------------
I may be old, but I’m not dead yet.

 

[aquaregia]

Beauchat Y?

 

[DevonDiver]

Redundancy of the regulators. It won't help you if the cylinder valve goes. Nice option if you do more aggressive recreational diving and/or baby penetration.

Can use a high capacity single with H/Y valve for some of the Advanced Nitrox and PADI Tec 40 course.

 

[Bearded Diver]

justt ran across twosteels that had a funny valve, now I know why.