O-ring Wear and Tear

[captain]

Most O ring failures at the valve /regulator connection are related to improper assembly, properly assembled there should be no room ( Gap,crack,space, etc) for it to extrude into. My bet is that was your problem. Once the yoke is tightened the O ring is compress until there is metal to metal contact between the valve and regulator which leaves no room for extrusion, it doesn't take gorilla strength to accomplish this. If the regulator isn't positioned correctly before tightening the yoke all the gorilla's in the world won't help. The few blowouts I have had I blame on myself for not getting it right the first time.

 

[billt4sf]

It's one of the reasons I went to DIN - .

No o-rings on DIN connectors? Nice!

 

[redacted]

There is another possibility which is worth considering - on yoke connectors you can actually damage and deform the o ring if you 'over tighten' when fitting the yoke. it stretches the o ring and can cause it to start to extrude out of the fitting. Over time this will cause a failure as you describe.

You only need to tighten the yoke enough to seat the connector faces correctly, and then tighten hand firm, and then pressure will make the seal. If it is so tight that it is hard to get off after the dive then maybe you are over tightening when fitting which will lead to premature failure.

It's one of the reasons I went to DIN - on the rental tanks I was using abroad the O rings were frequently b******d from being tightened to within an inch of their life and failures were quite common. - Phil.

I doubt that a properly installed o-ring that will withstand 3000+ psi can be damaged by tightening the yoke connector. But it can make disassembly difficult.

 

[Redshift]

I'm a bit surprised by this conversation. Granted, most people I know dive DIN, but I have dived yoke and seen many others using it. There was never any talk about o-ring size (apart from the obvious), hardness, position of the insert, tightening of the yoke, etc that I'm seeing here and I struggle to remember an o-ring blow out. I think I remember witnessing it once. One thing that needs to be properly done is having the face of the yoke well adjusted flat against the o-ring because it's possible to leave it a bit tilted.

 

[dmoore19]

I haven't seen an oring failure but if it is happening that frequently maybe the face of the regulator should be checked for damage?

Just a thought.

 

[j yaeger]

we had a whole bag full of o-rings come into the shop that were garbage
had them on our pool tanks and the kids were blowing them constantly
switched them out and problem was resolved

 

[Jim Lapenta]

I doubt that a properly installed o-ring that will withstand 3000+ psi can be damaged by tightening the yoke connector. But it can make disassembly difficult.

I've seen what I would call premature wear on yoke orings due to people cranking down on the yoke knob and crushing the o ring over time. They seem to get fuzzy faster. It is kinda cool when they go right at the surface in the pool and make snow.
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[Phil_C]

No o-rings on DIN connectors? Nice!

Obviously there are O rings on DIN, but they are not in the tank valve - they are on the face of the DIN regulator rather than in the tank, so YOU have control over what condition they are in (unless you are also renting regs). Also because they are on the face of the first stage they seat right at the back of the tank valve at the bottom of the 'hole' and therefore are tightly surrounded by metal on all sides and the o ring and mating surfaces have been lined up by the thread of the valve. Much harder to not get a flush fit and little chance for it to come out of its side. If you over tighten a DIN reg what tends to happen is the O ring "sticks" and comes out of its groove when you undo the valve, but that is very rare in my experience and also very obvious because it falls out.

Yoke on the other hand has the o ring and mating faces exposed at the 'surface' so it is vulnerable to getting the mating faces slightly incorrectly seated, overtightened etc.

Although to put things into perspective at is still very rare for a properly maintained tank o ring in good condition to fail if the yoke has been fitted correctly.

---------- Post added May 12th, 2014 at 12:29 AM ----------

I doubt that a properly installed o-ring that will withstand 3000+ psi can be damaged by tightening the yoke connector. But it can make disassembly difficult.

Sadly I have seen quite a few, and have looked at badly fitted yokes (slightly skewed) and seen the deformed o rings twisted out of their groove - like this they blow at the surface and leak straight away, but my buddy has also had a yoke blow at 22 metres at the bottom of the shot line at the start of a dive. We shut the tank off and made a shared ascent and when we took it all apart the o ring in the yoke had failed and was misshapen . - Phil