Valve drill and free flow - possible cause?

[R.Chisholm]

Recently on a practice dive at ca 30 feet in cold water I was practicing the valve drill starting with the shutdown of the right post of my twin set.

I signalled the start of he procedure and shut down the right post. I then breathed the right post down, switched to the necklaced backup from the left post and clipped off the long host and regulator (DIR configuration of all regulators)

As I opened the right post something started free flowing around the right post - however not the clipped off secondary which I could see.

I signalled I was going to abort the exercise (and dive) - however after ascending for 10 feet and having switched form the backup back to the primary the free flowing stopped.

So I decided to restart the exercise - same results, free flow which stopped after switching to the primary and a short ascent.

After the dive my buddy couldn't confirm where the gas was escaping so at the end of a later dive I asked a (different) buddy to take a close look - this time despite shutting down the right post and breathing it down nothing happened.

Equipment used are two DIN Atomic M1 regulators and a steel twin set with Halycon (labelled) valves. Since I own the twin set I know I have never dropped the set and damaged the valves. The regulators have been serviced a few times, the valves have been serviced once and all the o-rings in the regulators have definitely been replaced at least once.

It would appear that after breathing down the right post and removing pressure somehow re-applying pressure when the valve is opened fails to engage either the o-ring in the first stage facing the valve or one of the o-rings in the valve itself.

Any ideas as to what could be causing this?

regards,

Rory

 

[happy-diver]

Right so if you stick to diving mate there won't be any problems

 

[SlugLife]

The one time I forgot to pressurize or turn on my pony tank + regulators, it resulted in my regulators flooding, and a large amount of bubbles coming out from between the valve and the regulators. It was over a year ago, but I believe I had yoke regulators and tank-valve at the time.

I suspect the bubbles only stop, once the water is purged from your first-stage. I cannot comment on whether that's "normal" or happens every time or with every regulator.

 

[MightyDuck]

One time a similar thing happened to me.
The reason was when I shut the valve down and the pressure dropped and the first stage easily turned about 30 degree (togetherwith the valve part) and loosened (DIN) and when I opened the valve again, it started to releasing air. Not just leaking, it was clearly audible.
I closed again, release the air, tightened the first stage and opened it, problem solved.
Maybe similar happened to you?

 

[rob.mwpropane]

One time a similar thing happened to me.
The reason was when I shut the valve down and the pressure dropped and the first stage easily turned about 30 degree (togetherwith the valve part) and loosened (DIN) and when I opened the valve again, it started to releasing air. Not just leaking, it was clearly audible.
I closed again, release the air, tightened the first stage and opened it, problem solved.
Maybe similar happened to you?

That's what I was thinking... op, how "tight" do you make your regs? This would be the most logical explanation (to me).

 

[inquis]

Also, you don't have to hard-suck the reg during the valve drill. My AI shows me stopping at about 60 psi when I initially feel it lock up.

 

[J-Vo]

Any time you depressurize a reg this is possible. Nothing unusual. You should learn to solve it when it happens as it could be in a real situation.

 

[R.Chisholm]

That's what I was thinking... op, how "tight" do you make your regs? This would be the most logical explanation (to me).

Hi,

I had hand tightened both regulators - I'm certainly not using a lot of force to tighten then (i.e. a wrench). They were certainly not leaking until I performed the shut down and yes it was clearly audible.

I tried the whole thing again today and like last time (as opposed to the initial dive) could not reproduce the problem.

As to the other comment from jvogt that this is "normal" and something I should know how to solve. I suppose I could practice tightening a loose regulator behind my back - at this point however I'm still not entirely sure where the leak happened - i.e. was this really between the valve and the regulator, internal to the regulator or a defect in the valve.

 

[rob.mwpropane]

Hi,

I had hand tightened both regulators - I'm certainly not using a lot of force to tighten then (i.e. a wrench). They were certainly not leaking until I performed the shut down and yes it was clearly audible.

I tried the whole thing again today and like last time (as opposed to the initial dive) could not reproduce the problem.

As to the other comment from jvogt that this is "normal" and something I should know how to solve. I suppose I could practice tightening a loose regulator behind my back - at this point however I'm still not entirely sure where the leak happened - i.e. was this really between the valve and the regulator, internal to the regulator or a defect in the valve.

I have found the way I used to tighten my regs seemed to put a lot of strain on the hoses.. now I just tighten them in a way that makes the hoses look the most relaxed.. I also found I didn't like the noise of two hoses rubbing together behind my head, so usually one 1st stage is a few degrees more than the other.

No way can the hoses push / pry the reg, even without pressure.

No idea what your issue is, but I doubt it's the valve. I have had issues from the wrong size o ring and the threads of the reg having vertigus on them.. wouldn't let me tighten all the way.

 

[BlueTrin]

One time a similar thing happened to me.
The reason was when I shut the valve down and the pressure dropped and the first stage easily turned about 30 degree (togetherwith the valve part) and loosened (DIN) and when I opened the valve again, it started to releasing air. Not just leaking, it was clearly audible.
I closed again, release the air, tightened the first stage and opened it, problem solved.
Maybe similar happened to you?

I have had the same thing happening to buddy during a valve drill, the first stage un tightened and was leaking a bit.