Pony freeflow

[CRDiver]

How many people here who use a backmounted pony left on during the dive have had the pony reg freeflow, and what were the causes of the freeflow?

 

[wscdive]

thats why i sold my backmount bracket. (never had it happen to me but heard horror stories) find it very easy to dive it stage rigged and easier to monitor. I dive mine charged but turned off easy enough to turn on when needed.

 

[mempilot]

I'm with wscdive. Sling it as a stage rigged bottle. It doesn't do any good to lug it around if it leaks out and you didn't know it. I'd want to be able to decide whether to call the dive or change my plan based on whether I still have an emergency reserve bailout.

 

[DA Aquamaster]

There are definite advantages to slinging a pony but for many recreational divers, a backmounted pony is much less noticeable, requires no real change in technique as well as no additional skills and works with almost any rec BC where slinging requires appropriately located D-rings.

In practice a freeflowing pony is not going to be a problem unless you are really clueless and do not hear the freeflow. It's always a good idea to listen for bubbles during the pause between your exhalation and inhalation when diving. You will hear even very small leaks you would otherwise not see.

 

[HawaiiDiver]

Have used a pony for hundreds of recreational dives, in water temps ranging from 80 to 28 degrees, never experienced a freeflow. The freeflow issue is irrelevant anyway since a pony should be used for emergencies only, and its contents shouldn't be figured for use in your diveplan.

 

[mempilot]

Have used a pony for hundreds of recreational dives, in water temps ranging from 80 to 28 degrees, never experienced a freeflow. The freeflow issue is irrelevant anyway since a pony should be used for emergencies only, and its contents shouldn't be figured for use in your diveplan.

Agreed. But if it's being carried for a contingency, such as diving in an overhead environment or as a bailout for a CCR, and it's no longer available, then the dive should be aborted. Otherwise, why would one carry it?

This goes back to the Pony debate, which I don't want to rehash.

 

[CRDiver]

My question had nothing to do with the wisdom of using a backmounted pony. It was entirely about the rate of freeflow incidents and its causes.

I'm interested in whether freeflows are relatively rare enough to be considered a non-issue for *recreational* divers.

 

[mempilot]

My question had nothing to do with the wisdom of using a backmounted pony. It was entirely about the rate of freeflow incidents and its causes.

I'm interested in whether freeflows are relatively rare enough to be considered a non-issue for *recreational* divers.

Two types of mounting:

Sling:

Most slung stage bottles are charged, and then shut off to keep this from leaking gas at inopportune times. It allows you to monitor gas supply and the opperation of the valve. It can't freeflow, since the valve is shut down until needed.

Back:

With a backmounted bottle, the valve is usually left on during the dive due to access. With the valve on, a 2nd stage can free flow unless the cracking pressure is detuned. You would have to retrieve the 2nd and 'cork' it to stop the free flow. If the 1st stage fails, think hp seat, and you can't reach the valve, then all the gas will leave the tank. For recreational purposes, this is no big deal, since you don't need the gas anyway. See posts above regarding gas planning.

Does this happen? Yes. Often? Depends on your gear and how well it is maintained. Even the best maintained gear fails. I had a brand new DR manifold blow a 1 in a million o-ring a couple of weeks ago. It was in storage the night before a deep dive.

Slinging a bottle is no big deal. Try it, and see for yourself. It will give you flexibility for operation and donning/doffing the tank for passing to a buddy or boat crew if needed.

 

[CRDiver]

"Try it, and see for yourself."

I have. And once again, instead of staying on topic, the subject gets dragged into an area covered a hundred times....

I agree - slinging makes more sense. But for the second time, that's not what I asked about.

 

[mempilot]

Jeesh man, relax. I gave you several reasons for freeflows, why they happen, and how to deal with them based on which type of mount you do. I'm not trying to sell you anything. I answered your question.

1st stage problems don't happen all that often, but they do happen. They are typically caused by a hp seat failure. 2nd stage freeflows are more common. They happen from the cracking pressure being to low, or a particle lodged in the membrane, keeping it from fully closing. Charging the system, and then shutting it down is a preventative way of handling it. You must have missed it.

If you do a lot of cold water diving, you already know about free flows from freezing.