SEAC Synchro second stage diaphragm failure

[Nicolas Pottier]

Definitely falls in the minor mishaps side of things, but today diving in Puerto Lopez on a shallow reef in rental gear had my primary second stage start breathing wet in one breath and the next breathed almost completely water This was about 45' in at around 7 meters. Entire dive was shallow and had no safety stop needed due to that. After second breath of water switched to octopus which breathed fine, though really not a fan of the holder they used (mouthpiece style) as it was a bit hard to remove. At least it was where I expected it to be.

Unsurprisingly floated up during the switch and surfaced. Guide was on it and noticed me going up and followed. We were so near boat decided to not continue though offered to. Buddy came up a second later.

Later on the boat inspected the second stage, looked like a section of the diaphragm had just slipped out from the retaining disc. Interesting to me that that happened so far into the dive. It was easy to remove the ring and reseat it. Though I don't have much experience looking at different regulators the seating surface seemed kinda shallow to me, no idea if that design contributed to it unseating. (seems more likely poor assembly during a servicing?)

Thoughts / lesson learned:
* As with many chartered dive boats, it was a bit of a flurry when everybody gets in. Glad I insisted on doing my entire safety check including removing the octopus from it's annoying holder to breathe on it, I may have panicked trying to remove it when it counted otherwise due to its design.
* I *think* I could have made it to my buddy without another breath if my octopus was also not working but I doubt I would have had the discipline to try since I was so shallow. She was maybe 4 meters away but we were in surf so quite a bit of variable current. If it was life and death I would have made it I think but wouldn't have been fun. Is that the right distance? Of course things would have been that much more hectic by then as I would have wasted more time on getting octopus out and finding it didn't work either.
* Only more convinced that a necklace secondary makes sense after this.

In any case thought I'd share. Of course super minor in the world of dive incidents but maybe will instill others the extra courage needed to hold up the boat as you do your pre dive check.

 

[Raystafarian]

You say super minor but that could have easily resulted in much worse had the conditions been different or had you panicked - it's great to learn a lesson or be reminded of a lesson without it turning into a full-blown incident. Glad you handled it calmly and didn't feel like you needed to skip your pre-dive check!

 

[rsingler]

Diaphragm seating is an easy skill that you should ask your LDS to teach you. It's useful, simply to be able to clean out sand or other debris from your second stage, especially after beach dives or before putting gear away after a trip.
It's also very easy to be sloppy during reassembly after service, which is what I'm guessing happened here.
To prevent in the future, do a leak check:
With the reg set on the tank, BEFORE you pressurize, take a "medium suck" attempted breath from the reg. Not so hard that you'll pull the exhaust valve through the spokes on the case, but...medium. There should be no air hissing into the case as you suck. If there's no leak, you're good to go.
In this case, I'll bet that this test would have pulled the diaphragm loose from the retaining ring, and the reg would have leaked like crazy.
Another reason to become familiar with
Regulator Inspection and Checklist (Rev-8)
ESPECIALLY with rental gear.

 

[Nicolas Pottier]

Thanks, that's a great tip. I've watched a few 2nd stage teardowns, enough that I suspected it was a diaphragm failure before returning to the boat but I don't have my own gear yet so haven't had the chance to play with one in the flesh. One of the requirements of whatever regs I end up with is being able to service them myself.

I will definitely give the "medium suck" a go on my next rental set, I imagine you are right that it would have unseated then. Still surprised it went 45 mins before failing so completely!

 

[JamesBon92007]

I suppose that would have been a tough one to spot even with a pre-check. It could have seemed fine on the surface with a few breaths. The same thing with a stuck exhaust/purge valve but at least you can check it with the air off and see if you get any air from anywhere. I wonder if that would have worked in this case (?). Sucking on it with the air off might have popped it off. Is this the kind of second stage that requires tools to remove the cover, or does it simply unscrew?

I don't know if they teach it or how many people do it but I always turn my air on, look at the SPG, and turn the air off. Then I wait a couple minutes. If the pressure holds that indicates no leaks (other than very tiny leaks). One time time the pressure dropped when I forgot to release the pin that holds down the purge button to save the valve seat. Another time it turned out to be the tank valve O-ring and since I couldn't hear any air leaks this pressure check prevented me from jumping off the boat and then getting back on and switching tanks etc.

As for the octopus holder, I have one that clips onto the hose and a slight yank and it is free. Anyone can do it without even knowing how it's attached. I sometimes wonder what people are thinking when they come up with some of the "safety" devices.

Anyway, glad your octopus worked and everything ended well. Somewhere in the back of my mind there's always the thought lurking: OK, dude, what's the plan if things turn to s**t right here? This, of course, keeps updating as things change but it's always there...

 

[Nicolas Pottier]

Is this the kind of second stage that requires tools to remove the cover, or does it simply unscrew?

It is, didn't need any tools on the boat to take it apart and see the unseated diaphragm. So ya maybe the medium suck would have been a good test. From my limited experience that'd be an even longer bridge to cross on a busy boat as the crew sets everything up, turns on tanks etc.. but maybe on the first dive of the day (on whatever regs they give you) that's not such a big deal if you are on it, just may get some looks.

Then again I now have a good reason as to why I would want to do that so they can just wait already.

 

[JamesBon92007]

It is, didn't need any tools on the boat to take it apart and see the unseated diaphragm. So ya maybe the medium suck would have been a good test. From my limited experience that'd be an even longer bridge to cross on a busy boat as the crew sets everything up, turns on tanks etc.. but maybe on the first dive of the day (on whatever regs they give you) that's not such a big deal if you are on it, just may get some looks.

Then again I now have a good reason as to why I would want to do that so they can just wait already.

On the dive boats I've been on usually the tanks/equipment are set up a little ahead of time so I can leisurely check my gear. But, if it wasn't that way, I'd still check my gear and they might have to wait 3 minutes. I like it best when they ask if I would rather do it myself.

At least if you did the suck test and it popped off you could easily unscrew it and try to fix it. I wouldn't want to be unscrewing the kind that has a ring around it and a screw that could get lost while on a boat that is bouncing around

 

[rsingler]

I like it best when they ask if I would rather do it myself.

+1!
Just returned from a week's vacation in Grand Cayman with a "valet diving service". Twenty folks from my LDS. Most were happy to have their gear set up and waiting. I always brought my regs and didn't leave them on the boat. It took a day or two, and the exchange was always cordial, but they learned that I took care of my own gear, even at tank change time.
Hey, one less set for them to worry about!

Don't hesitate to take charge of your stuff, even if it's rented, and even if the DM's say, "I'll take care of that for you!"
A polite, "No, thank you." is all it takes.

 

[chillyinCanada]

I always let them set it up if I'm diving with valet service. However after they have done that, I check everything over and I do that before every dive. From time to time, I'll notice other divers observing that I'm doing it and soon enough they are doing it too.

Of course there are always a few that think I'm obsessive. That's okay with me. It's none of my business what other people think of me.

 

[rsingler]

Okay, trick question:
If your reg is now really, really wet, and supposing your rental octo just doesn't work, period! What do you do?
Oh, yeah...your buddy is also gone...

Answer in next post...