Blown O rings?

[ScubaSarus]

I don't mean to hijack the thread but will a DIN converter solve the problem or because the converter has an o-ring its self, will it add an area were an O-ring can blow causing a loss of air.

 

[slowhands]

I don't mean to hijack the thread but will a DIN converter solve the problem or because the converter has an o-ring its self, will it add an area were an O-ring can blow causing a loss of air.

In a DIN connection, the O-ring is better captured mechanically -- a big advantage over INT fittings. It has no chance of extruding out from between the valve and din adapter. But if the O-ring is split or covered with dirt, it will still leak, but the leak is inside the well of the DIN valve. The air has to pass through all the threads, so is more restricted and will flow more slowly. This will give more time to surface.

Because of the dirt issue, keep the valve covered when it has no regulator, and cover the regulator with a cover too. Change the O-ring annually or more frequently based on conditions. It is wise to check the O-ring for quality and seating every time you put on any regulator, and carry a prudent number of spares.

Most of the O-rings I have seen lost on INT valve tanks (non-DIN) were not bad, but they somehow got dislodged in handling of the tank, before the regulator was put on. This was on boat dives, when the guys filling the tanks between dives are rushed and pop the fill hardware on and off like jugglers and the skill of divers was also mixed.

Slightly off topic, I have had a turret O-ring fail inside my first stage, a Scubapro MK2. This was scary, but I was able to surface and swap it. But I kept thinking, what if I had been in a wreck or other covered environment? Based on that experience, I decided to buy the best first stage I could get in terms of reliability, to avoid turret versions (the turret O-ring was what failed, why not eliminate it?), and to make sure the regulator was environmentally sealed. I went to DIN fittings too, mainly due to the more secure O-ring.

 

[DA Aquamaster]

Slightly off topic, I have had a turret O-ring fail inside my first stage, a Scubapro MK2. This was scary, but I was able to surface and swap it. But I kept thinking, what if I had been in a wreck or other covered environment? Based on that experience, I decided to buy the best first stage I could get in terms of reliability, to avoid turret versions (the turret O-ring was what failed, why not eliminate it?), and to make sure the regulator was environmentally sealed.

The Mk 2 does not have a swivel turret so it does not have a swivel turret O-ring and consequently your story and your advice has some serious credibility problems.

Actually, it sounds like a blatantly biased pot shot at SP regs. Just wondering if maybe you own Apeks regs?

In the case of the MK 5, Mk 10, Mk 10 Plus, Mk 15, Mk 18, Mk 20 and MK 25 that do have swivels and swivel turret o-rings, I have never seen one fail in 20 years of divign and working on regs nor have I ever even heard of one failing in a catastropic manner.

In the case of a swivel turret o-ring it is well contained and as it is only exposed to intermediate pressure of 120-145 psi it is not going to extrude and cause a catstropic leak. If it does anything, it will develop a very small leak visible by an occasional bubble leaking from the base of the turret during the dive. Your dive buddy will find it in a bubble check long before you ever notice it and long before it poses a threat of significant air loss or even becomes "scary".

SP did address this expressed customer concern in the Mk 9, which was a Mk 10 with out the swivel turret. If you find one buy it, not because it is more reliable, but because they did not sell well and were not produced for long as the infintismally greater reliability was far outweighed by the advantages of a swivel turret and the extended hose life that results from having one due to less stressful hose routing. You are far more likely to experience a leak from a hose that fails due to having too tight a bend in it than you are of ever having a swivel seat o-ring leak.

 

[pcosens]

If you are truly concerned about an o ring extruding / blowing out of a yoke connection do yourself a favor and inspect it carefully BEFORE you install the 1st stage. Very common for the o ring to be partially "pulled" out when the 1st stage was last removed, then it gets pinched when you next install 1st stage - you see it as an o ring failure but the poor thing never had a chance.

The white o rings are probably a urethane material (or derivative) as apposed to neoprene or buna material (common black ones). They are typically tougher and last longer, but are still subject to pinching. Only takes a second to look B4 installing your reg.

Only seen 1 failure in the water - 70 feet, old dry o ring disintegrated and went through the 1st stage internally. Complete air blockage with associated holy sh##t reaction. Probably why I always carry a redundant system . . .

Paul

 

[jerryn]

I had an o-ring extrude once. It was on a tank with a DIN insert to take a yoke connector. The DIN inserts do not provide as tight a seat as the K-valves and it is easier to have an extrusion. Extra care in attaching the first stage should solve the problem.

I lost about a 1/3 of my tank and surfaced right away. Blew at 45'

Jerry

 

[Marek K]

You know, a lot of people say that a yoke valve o-ring is more susceptible to failure because it isn't "captured" as well. I'm not sure that's correct.

Assuming it's a good o-ring, it's captured quite well once the yoke 1st stage is attached... the 1st stage's round flange caps off the groove in which the o-ring sits; the o-ring then really has nowhere to go. You just don't have that deep well of the DIN valve, but that doesn't contribute to the o-ring's function.

In the same way, a DIN 1st stage o-ring is captured only once it's attached to the DIN valve.

If a yoke o-ring is going to extrude, it's going to do so before the 1st stage is put on. And if the o-ring itself (old, damaged, defective) is going to fail while properly connected, then it shouldn't make any difference what kind of fitting it is.

I think the reason people see many more yoke o-rings fail is for a couple reasons: Unless they're carefully capped, o-rings on yoke tank valves are exposed to potentially more abuse than o-rings on DIN 1st stages; or we're dealing with rental tanks, whose care can't be vouched for.

Those doughnut-type screw-in DIN-to-yoke insert adapters are going to be even more abused than tank valves; and there are twice as many o-rings to worry about there.

The reason I converted to DIN fittings was primarily because I'm in Europe now, and don't care to depend on those doughnut adapters. Plus I do agree that it's a more-secure connection.

And if anyone were to accuse me of grabbing the yoke knob by accident when I was shutting off my air, I'll deny it.

--Marek

 

[Nemrod]

I have had a DIN O-ring extrude out! I have also seen a few standard valve O-rings fail, in every case, DIN or standard, there was dirt, damaged valve or regulator sealing surfaces, aged and or damaged O-rings or the regulator was installed without insuring the O-ring was seated thus pinching it.
I just had an O-ring fail--extrude--in my Voit MR12 regulator in the high to low pressure seat area. This regulator has new parts and has never failed before--hundreds of dives. It had just been used as back up on a dual manifold rig while in an overhead environment. It failed when turning on the air for my next dive. I think I may have put to much grease on it or pinched it while overhauling.
I have never had a turret leak in any of several such regulators I have.

I think DIN is more stable but for open water rec diving standard valves are entirely capable and more than adequate. N

 

[Scubaroo]

I don't mean to hijack the thread but will a DIN converter solve the problem or because the converter has an o-ring its self, will it add an area were an O-ring can blow causing a loss of air.

Are you referring to a DIN adapter? i.e. the adapter that lets you screw a DIN reg into it, and attach to a yoke valve? A DIN adapter still has a yoke interface. You're just making the regulator stick out more. DIN adapters are for using DIN regs on yoke tanks, where you either a) can't convert the reg to yoke by removing the yoke fitting and replacing with the DIN fitting, or b) can't be bothered

 

[derwoodwithasherwood]

I understood the principle advantage of DIN over yoke is that a yoke is far more susceptible to loosening up under pressure and that's what blows o-rings during a dive. There's two factors involved: first, a yoke can stretch slightly -- more so as cylinder pressure increases. More importantly, for some strange reason the powers that be at CGA decided a scuba yoke didn't need to fit snugly over the valve, nor did it require index pins and for this reason it can rotate, mechanically loosening it. If either connection -- DIN or yoke -- is too loose then the o-ring may extrude.

I was taught to rotate the yoke counter to the direction of turning the knob when tightening the connection. That way, the yoke can only get tighter if it shifts. Allowing the yoke to rotate with the knob sets it up to loosen if it shifts. Am I just stating the obvious or do they not teach that anymore?

 

[Marek K]

Interesting points!

first, a yoke can stretch slightly -- more so as cylinder pressure increases.

Enough, you think, to make a practical difference? Of course, there might the issue of metal fatigue over time... but how often has a yoke actually broken? (I'm sure there have been instances... frightening thought!)

More importantly, for some strange reason the powers that be at CGA decided a scuba yoke didn't need to fit snugly over the valve, nor did it require index pins and for this reason it can rotate, mechanically loosening it.

Hmmm... Seems like the maximum a yoke could rotate, from all the way over on one side to the other, would be less than 1/4 of a turn... I don't know whether that would be enough to "open up" the o-ring to allow it to extrude. But maybe, especially if the knob isn't tightened properly...[/QUOTE]

I was taught to rotate the yoke counter to the direction of turning the knob when tightening the connection. That way, the yoke can only get tighter if it shifts. Allowing the yoke to rotate with the knob sets it up to loosen if it shifts. Am I just stating the obvious or do they not teach that anymore?

I'm not sure they ever taught this as a standard... I don't remember it from my OWD in 1985, or AOW in 1986. I'd guess it was because it really didn't make that much of a difference.

Makes sense, though... except that it seems like the yoke should be rotated over in the same direction as you're tightening the knob. Looking from the back, as you're tightening the knob clockwise, at the end you should make sure the yoke is also clockwise as far as it will go. That way, if it were to rotate counter-clockwise, that would tend to tighten the threading. Or do I have that wrong?

But there might be another issue... as the 1st stage itself moves slightly back and forth -- admittedly that doesn't happen much, once the thing is pressurized -- the inlet flange will rub on the o-ring... with at least the potential of wear. But no... that can happen with DIN too, just the other way around.

Please understand I'm no expert... I'm just talking as a lay person.

--Marek