Failed CESA in OW

[Belzelbub]

I did never understand why double valves with reserve went out of fashion. They were the standard here in Europe 30-40 years ago. And I still have one on my 15-liters steel Cressi tank.

While your experiences seem to indicate otherwise, I suspect the reason they went out of favor was due to a lack of need. Tank valves with reserve were largely replaced by SPGs. Double valves mostly went away as they just weren needed. Regulator failures are fairly rare, and if diving with a buddy, there are other options in the event of a regulator failure. Solo and overhead environments require more redundancy than recreational open water.

I have also only been in the vicinity of only two OOA situations in that time.

Mostly the same for me. I’ve seen two OOA-like situations.

In one case, it was noticed at the surface. My buddy just felt his reg was not delivering enough gas. Everything looked OK, so I swapped his reg with a spare. He had recently gotten his reg serviced and the shop screwed something up. They never came clean on what, but it must have been bad as they replaced his second stage. He doesn’t use that shop anymore.

In the other, was diving off my friend’s boat with him and one other. Boat owner found an anchor, and was trying to untangle. I handed him my knife and he cut the line and handed it back. I sheathed it, and when I looked up, he was gone. He opted for a CESA, which was not the best option, as both other divers still had some gas left.

 

[Angelo Farina]

Wow! The people you dive with must use really crappy equipment. I cannot begin to estimate how many people I have dived with around the world in my diving lifetime, and I have never seen a regulator fail under water.

I have also only been in the vicinity of only two OOA situations in that time.

• In one case, a diver in my group clearly did not check her gas supply before the dive, because she was OOA after only a few minutes at depth. She calmly took her husband's alternate, and we all did an orderly ascent.
• The other case was just a few weeks ago. It was a wreck dive in South Florida, in which the procedure is for the DM to descend to the wreck and tie off a line leading to the boat for people to descend and ascend. When she got back to the boat, she warned of a ripping current, and she was right. I was the 4th one down the line, and two of the people ahead of me (very experienced divers) quit during the descent, exhausted from pulling down the line into that current. I later learned that nearly half of the divers quit during the descent. After the dive, one of the divers said he had not realized how much air he had sucked down on that descent, and he had started the ascent without enough air. He ran out during the safety stop and calmly shared air with his buddy's alternate.

Summary: I have never seen anything like your "more frequently" experiences, and the only two cases of OOA I have seen were easily handled with the use of an alternate.

All those failures, except one, occurred during a 3-month shift at Maldives, were I was working together with my wife as instructors and DMs.
Yes, it was an equipment problem.
We got a batch of O-rings for our yoke valves which were the correct size but the wrong durometry, so they were easily extruded.
This usually happened while testing the equipment on the boat, where I have witnessed something as one hundredth of O-ring extrusions. Perhaps more. One day on the dhoni all our 8 tanks (6 for divers, 2 for deco) had an O-ring extrusion before the dive!
But the problem sometimes happened underwater, at least 10 episodes. Usually at the beginning of the dive, just while jumping in water or soon after.
Not a big issue, as we all were prepared to this: affected valve is closed and the diver can breath with the other reg.
No need for a Cesa or getting air from the buddy or the DM.
We managed to get some good O-ring from customers who had spare parts with them, but they were not enough for fitting all of our tanks. So these O-rings extrusions went on for a couple of months
The batch of good O-rings finally arrived from Italy just one week before the end of my 3-months shift.

 

[ScubaWithTurk]

Some OOG events I witnessed were simply due to 2nd stage misfunctioning. Doing a Cesa in such cases is a wrong choice, you can just breath from your alternate air source.

If that is the case, again, it isn't an OOG event. It is an equipment malfunction. If a diver is Out Of Gas, switching to the AAS does no good because they are Out Of Gas.

 

[Belzelbub]

We managed to get some good O-ring from customers who had spare parts with them, but they were not enough for fitting all of our tanks. So these O-rings extrusions went on for a couple of months
The batch of good O-rings finally arrived from Italy just one week before the end of my 3-months shift.

Wow. At least 3 months to get some replacement yoke o-rings. That seems crazy. Yes, I realize, I’m looking at this with 2023 glasses, but I would have never expected that a yoke o-ring would have ever been that hard to come by.

I have a few yoke o-rings in my SAD kit, and I don’t even use yoke regs.

 

[Angelo Farina]

Wow. At least 3 months to get some replacement yoke o-rings. That seems crazy. Yes, I realize, I’m looking at this with 2023 glasses, but I would have never expected that a yoke o-ring would have ever been that hard to come by.

I have a few yoke o-rings in my SAD kit, and I don’t even use yoke regs.

It was 1986. No internet, no phones on our remote island...

 

[Belzelbub]

It was 1986. No internet, no phones on our remote island...

That makes a bit more sense. But only due to the remote location. A yoke o-ring is not hard to come by today, and likely ever. I’d qualify those failures you witnessed back then as a special cause. Definitely not what would be considered as a typical failure rate.

I would hope a dive op today wouldn’t continue using a suspect batch of bad o-rings.

 

[Angelo Farina]

If that is the case, again, it isn't an OOG event. It is an equipment malfunction. If a diver is Out Of Gas, switching to the AAS does no good because they are Out Of Gas.

Technically you are entirely right.
But from my point of view an OOG event is when a diver makes the OOG signal, or acts as if he/she is out of gas. Often this is not technically true (with our 15 liters tanks with reserve there is always some amount of air trapped inside it), but the effect is the same: the diver needs an alternate gas source, or to reach the surface.
Just two cases:
1) a student had glottis lockage after removing his mask, so he could not inhale or exhale, and he sprinted for the surface.
2) my son had the first stage clogged by rust inside the tank. So only a very small air flow was released.
I consider them OOA episodes, although in both cases the tank was full.

 

[Angelo Farina]

That makes a bit more sense. But only due to the remote location. A yoke o-ring is not hard to come by today, and likely ever. I’d qualify those failures you witnessed back then as a special cause. Definitely not what would be considered as a typical failure rate.

I would hope a dive op today wouldn’t continue using a suspect batch of bad o-rings.

Definitely it was a very anomomalus case.
But it did provide me a lot of experience about O-ring extrusions!
The first one I have seen underwater, it scared me a lot. But after the third or fourth case, we learned how to deal with this problem.
We did not even consider them as accidents, so no accident report was written anymore.

 

[BoltSnap]

That makes a bit more sense. But only due to the remote location. A yoke o-ring is not hard to come by today, and likely ever. I’d qualify those failures you witnessed back then as a special cause. Definitely not what would be considered as a typical failure rate.

I would hope a dive op today wouldn’t continue using a suspect batch of bad o-rings.

It depends on location and circumstances. I am in Libya and I needed book screws to attached something to a BP, it took about a month for them to arrive and the shipping cost a lot more than the screws themselves. Payment in foreign currency from here is a huge problem especially for small amounts. Local black market guys aren't interested in small amounts. If managed to pay for them because my brother overseas payed for them. It will be the same issue for o'rings or even worse.

You are living in a different universe from us

 

[Belzelbub]

It depends on location and circumstances. I am in Libya and I needed book screws to attached something to a BP, it took about a month for them to arrive and the shipping cost a lot more than the screws themselves.

Yeah, I get that. Book screws are on a whole different level from a standard yoke o-ring. If a business is more or less built around yoke tanks, you’d hope that the cheapest part wouldn’t be a problem. I don’t use yoke o-rings, but I have enough DIN o-rings to probably handle enough dives for me and many others in the foreseeable future.

It’s often the cheapest parts that are the problem. I do get that. I’m just surprised that this was such an issue for so long. Without tanks, most vacation dive ops wouldn’t operate. A reliable supply of a critical, and comparatively cheap part, should not be an after though.

I get that bad parts can happen. I’m just struggling to understand how it could be a 3 plus month issue. In 1986, it’s more understandable. Today, I’d hope not.

You are living in a different universe from us

Yeah, probably, but Italy is not Libya. I wouldn’t be surprised if a good number of my o-ring stash came from Italy.
My supply of yoke o-rings is relatively low compared to some other sizes, but I probably still have enough to handle every tank on a typical charter boat. If it were me, and I ran into an extruded o-ring on a tank, I would probably replace it on my next tank.