Yoke Valve On Pony/stage Bottle

[2airishuman]

I have a mixture of yoke and DIN valves on my cylinders and regulators. As much as I would like everything to be DIN, the dollar cost of converting everything is high.

In another thread, someone pointed out that stage bottles, when carried with the valve off, pose a particular problem with yoke valves. When the yoke connection is not pressurized, the clamp bolt turns easily. It may come loose, leading to extrusion of the o-ring once the stage is needed and the valve turned on.

I am wondering whether this is a practical problem or just a theoretical one, and whether there are effective ways to mitigate it, be they procedural (tighten yoke before opening valve), skills based (don't bump the clamp bolt), or equipment based (friction device on bolt).

 

[PfcAJ]

just go din. its a real thing. 2 knobs that look and feel the same/similar but do very different things isnt great.

 

[Tug]

You can chatge the bottle at the beginning of the dive and then periodically open and shut the valve to keep the system charged. This takes more work but until you can change over to DIN that's probably your best option if you want to keep the valve shut during your dive.

While not the same thing (but a similar concept), I keep my rebreather bailout bottle on the whole dive. By keeping the valve open, I can just pop the second stage in and instantly have breathable gas.

 

[uncfnp]

Yep. 3 ways to approach it. Keep the tank valve on all the time so guaranteed pressurized and no need to turn any knobs.

Or pressurize and turn off and know which knob you are turning when you need to turn valve on.

Either way you should maintain pressure in the the hose so that water does not enter. That's why it is important to either check pressure or crack the tank occassionally during the dive if you elect to turn off at the valve.

Third is an inline shutoff.

 

[Searcaigh]

Stages and ponies should always be DIN, and you should be in the habit of pressurising them without looking too as you are diving, a yoke first stage is going to complicate things, you can keep them for your backgas tanks if using a single cylinders but if you move to doubles you will need to go DIN.

 

[uncfnp]

I dove a yoke pony for years because the reg set I used then was not convertible. And because the tank was a 13 cf I dove with valve shut. Doable but like the others, not my first choice.

 

[dumpsterDiver]

If you are carrying the bottle slung position, what is the probability that you will experience a significant freeflow that will be allowed to continue for a duration sufficient to endanger your air supply? In other words if it starts to freeflow under your arm pit, shut the damn thing off.

As a practical matter how long does that take? Following the practical aspect, so you have a freeflow, so you are a dork and loose half the volume before turning a knob....what is the seriousness of this situation? Answer: probably nothing.

For recreational diving you have lost half your redundancy volume... Big deal.,. Go up if you want. An emergency has not occurred.

Leaving the tank off and playing with it, requires more work, may blow the oring, and if you scew up you may flood the reg with saltwater - something else which can be avoided by leaving the bottle on.

Just tighten up the seat in the second stage and freeflow should not be a concern. From a practical perspective, why be monkeying with the valve the whole dive?

 

[2airishuman]

DD, maybe you're right and I'm making this too hard. The idea at work here is that the closed tank valve is not only to protect against freeflow, it's a layer of protection against grabbing the wrong reg. Maybe with a slung pony that isn't much of a risk because due to the fact that the 2nd stage is bungeed to the cylinder, and that makes it pretty clear.

 

[uncfnp]

If you are diving slung with hose stowed until use, can't imagine how you could confuse them. Choosing to shut the valve to prevent mix up is no solution.

What reg are you wanting to use on your pony? My SP regs are super easy to convert. So were my Aqualungs (except the Calypso).

 

[Bob DBF]

I always keep my pony on as I use a Sherwood dry bleed reg, and I always thought that if the pony is turned off it is not immediately available in an emergency. See DD for the rest of my answer.


Bob