Small Leak at Tank-Yoke fitting?

[dudiver]

On my last dive I had a small leak around my first stage at the tank-regulator interface (yoke valve \ rented tank). I found this leak after entering the water on a shore dive. My buddy and I made our way back to shore and he re-fitted my regulator to the tank. The leak continued.

This leak was very small but persisted throughout my dive. We agreed to keep the dive shallow (7m) since I was having this problem. I inspected the o-ring on the tank and it seemed to be in order, but I did not remove it for a full inspection.

My questions are:
- Does this happen often?
- Is this type of failure likely to result in a dramatic increase in loss of air or continue at a persistent pace? In other words do orings often fail dramatically or typically with small leaks?
- Other causes besides bad o-ring?
- Was I taking un-needed risks by continuing with the dive?

I would appreciate any thoughts on the matter.
Cheers

 

[MikeFerrara]

It is common and it's usually the o-ring although if the sealing face of the reg or valve is damaged it could also cause a leak.

Carry some extra 0-rings.

 

[sharkmasterbc]

What Mike said....it is fairly common and could possibly lead to a catastrophic loss of gas. I have only ever seen one o-ring go completly and it was in a pool in shallow water. All we heard was a very loud bang and then a very loud hissing noise. If this were to happen to you whylst diving you could quickly turn off your tank, breathe the hoses dry, then turn it on again to pressurise the system and once again shut it off, breathe hoses dry and repeat. Once u get a good rythem going you can safely ascend to the surface. Of course a better option would be to shut down....signal out of air to your buddy (who should be already holding out his longhose for u) and share air. yet even better....you could shutdown and go to a redundant airsource....signal OK to your buddy and abort the dive.
You were smart to limit your depth and the small bubbles you could see are most likely a sign that the o-ring needs to be changed sooner than later. Carry spares and one of those dental picks, they make good pooky o-ring removing tools.

 

[Diver0001]

<snip>

My questions are:
- Does this happen often?

Yes.

- Is this type of failure likely to result in a dramatic increase in loss of air or continue at a persistent pace? In other words do orings often fail dramatically or typically with small leaks?

small leaks can lead to big leaks. It's not wise to ignore it.

- Other causes besides bad o-ring?

regulator damaged, valve damaged or kit not assembled correctly.

- Was I taking un-needed risks by continuing with the dive?

I would have changed the o-ring. Changing the o-ring takes 2 seconds if you have a new one around. I think you just identified something you need to have with you in a "save a dive" kit every day. If you can't change the o-ring you can sometimes solve the problem by removing the old o-ring and putting it in back-to-front.

R..

 

[pescador775]

O ring
From now on secure a spare O ring to the regulator with a piece of thread. The O ring should be of the white, silicone type. This type is made of harder material and resists environmental degradation due to its composition. Torque the regulator yoke firmly onto the ring.The problem of a leaking O ring occurs more frequently with rental tanks, possibly due to sand or grit, boat operators or dive shop monkeys damaging the valve's metal groove while digging out an old ring. Don't dive with a leaker, it can blow out. A good valve matched to a good O ring is safe to 4000 psi. However, this is only true if the regulator orifice has no deep scratches, check.

 

[dudiver]

Thank you all for the replies to my questions! Most of my thoughts were confirmed. I will purchase a few o-rings and a pick to remove as suggested. Also, I like the idea of attaching the spare where it can be easily found. Next time I will reverse the oring or replace.

After examining the tank I noticed some missing metal on the inside of the o-ring. I wasn't sure if that would cause a leak. It sounds like that could have been the cause as well. I was thinking I didn't need my own tanks. Now I am re-thinking this. It is nice to know where your gear has been!

 

[Ontario Diver]

Thank you all for the replies to my questions! Most of my thoughts were confirmed. I will purchase a few o-rings and a pick to remove as suggested. Also, I like the idea of attaching the spare where it can be easily found. Next time I will reverse the oring or replace.

After examining the tank I noticed some missing metal on the inside of the o-ring. I wasn't sure if that would cause a leak. It sounds like that could have been the cause as well. I was thinking I didn't need my own tanks. Now I am re-thinking this. It is nice to know where your gear has been!

Be very careful using a dental pick as they can mar the soft metal of the yoke which would lead to leakage. A plastic tool is better if you can find one.

 

[Charlie99]

From now on secure a spare O ring to the regulator with a piece of thread.

Some regulator dust caps have an o-ring in them, so get one of those and you automatically have a spare o-ring, nicely protected, hanging from your reg --- right where you need it if you have a problem just before jumping in. Just don't forget to replace the dust cap o-ring before rinsing your reg!

Another tip is to setup your gear, check air pressure, and then turn off the valve. Check the setup a few minutes later to see how much air pressure has bled off. This crude leak check method works even on noisy boats although it doesn't distinguish between a leak and a 1st stage with IP creep.

--

If you don't notice the leak until hopping into the water and doing a bubble check (at 15', for example), often all it takes to correct it is reach up behind and rotate the reg back and forth a bit.

 

[pescador775]

Careful! Often, the dust cap O ring may be of a different type than the valve O ring. Many years ago, the dust cap O ring and the valve O ring were the 'thick' type. Now, the valves use a 'thin' O ring and some caps, if they have a ring at all, use the 'thick' type. They are NOT interchangeable. If the O ring is the correct type check to see if a tool is needed to remove it or if removing it will cause damage. The dust cap does NOT have an indent like on the valve which allows one to get a purchase on the ring with a dental pick.

Some regulator dust caps have an o-ring in them, so get one of those and you automatically have a spare o-ring, nicely protected, hanging from your reg --- right where you need it if you have a problem just before jumping in. Just don't forget to replace the dust cap o-ring before rinsing your reg!

Another tip is to setup your gear, check air pressure, and then turn off the valve. Check the setup a few minutes later to see how much air pressure has bled off. This crude leak check method works even on noisy boats although it doesn't distinguish between a leak and a 1st stage with IP creep.

--

If you don't notice the leak until hopping into the water and doing a bubble check (at 15', for example), often all it takes to correct it is reach up behind and rotate the reg back and forth a bit.

 

[Charlie99]

Careful! Often, the dust cap O ring may be of a different type than the valve O ring. Many years ago, the dust cap O ring and the valve O ring were the 'thick' type. Now, the valves use a 'thin' O ring and some caps,.....

Thanks for the warning. In both cases, I'm referring to the 2-014, not the old 2-111 o-ring.

If you have any doubts as to what's in the dustcap, just pop one of your spares into it. The 2-014 is what works with the aftermarket dustcap I use with my Atomics B1. At it's last service, the reg tech replaced the o-ring in my dustcap. I now have a "nitrox compatible dustcap".