Second stage flooding?

[wakeupndive]

My trusty regulator (scubapro MK20 with a R380 second stage) has not failed me in ten years, so IÃÎ writing in for advice on the first problem IÃ×e ever had with it. ItÃÔ been serviced every year at the shop except for a few-year stretch in the middle when I wasnÃÕ diving. Just before this trip it was serviced by a dealer I have not been to before, and it'd be great to hear your advice before I go back to ask for help or possibly complain.

We dove in mild current, six degrees Celsius in the fjords. On set-up and dropping in the regulator worked fine, but about ten or fifteen minutes into the dive water started entering the second stage on inhaling. There was a little bit of air coming through but a lot of water, so after two or three breaths I switched to the octopus and cut the dive a bit short. No problems with the cheapie octopus. Back on the surface when I inhaled, no air came through the second stage, though the octopus still worked fine. My clod of a buddy gave the reg a few whacks and suggested I was holding it wrong. Then I adjusted the small dial on the front of the reg (that is usually left pointing to the word ÅÅive? which yielded a soft free-flow sound, but allowed me to breath a little bit on land. By adjusting this dial I could get it to free-flow more and stop with a whack, but allow a little more breathing. However, to get it to breath normally it had to be adjusted to a full-on free flow. I tried it at an intermediate setting the next day and immediately had the same problem with water filling the second stage. Immediately switched to the octopus, and used it for the rest of the week.

After this week I washed and dried my gear, checked it as baggage for a long flight with stops along the way for work and fun in New Zealand. In strong surge, fifteen degrees Celsius, I dove again two weeks later, and on setting up the gear everything seemed to work fine, except the plastic cover of the octopus cracked and had a little hole with the plastic missing. The shop owner opened it up and assured me the plastic cover was cosmetic, diaphragm intact. Both regs worked on land. Then I jump in for the dive and a repeat of the first experience, where my scubapro worked fine for about ten minutes, then water entered the second stage on inhale, and after failing to clear it for several ÅÃreaths I switched to the octopus. The octopus worked flawlessly even with a hole in its cover and I completed the dive without incident.

Any guesses? Here are my wild speculations:

(1) DAMAGE ON ROUTE
The trip to remote parts of southern Chile was rough, involving multiple flights, vans, and fishing boats, so it is possible the regulator was banged or otherwise harmed along the way. In retrospect I wish I had transported my gear in a hard crate, since it was often in the hands of others.

(2) SOMETHING DISRUPTING DIAPHRAGM
There was a fair amount of fine ash or clay-like glacial sediment in the water, especially on the first dive where gear was being tested and lots of sediment was kicked up. Maybe something stuck in there? Why didnÃÕ it come loose when rinsed?

(3) PURGE BUTTON
Why doesnÃÕ the purge button help this? Am I forgetting how to use it properly due to complete lack of incident for most of my diving experience?

(4) CRAPPY ANNUAL SERVICE
Maybe the shop made a mistake in the annual service, they also replaced the recall part for the MK20 and could have erred. But I'd be really disappointed if a routine service trip caused this problem.

By the way I found an older thread of someone diving in extreme currents and having this flooding problem - the current I was diving in was not that strong, at least I've been in stronger without any regulator issues.

 

[driftwood]

Most of the time when a second stage is breathing wet you have a torn mouthpiece.

 

[redacted]

First of all, the small dial on the front of your regulator must be pointing toward the "dive" position when the reg is to be used. Turning that dial rotates a lever that depresses the purge slightly to relieve pressure on the LP seat when the reg is stored. Under pressure, that should cause a freeflow to one degree or another.

As far as the intermittent but serious leak, my prime suspect would be the exhaust valve. But all the soft parts sealing the case including the diaphragm and friction ring, mouthpiece, and the o-rings sealing the body, plug, and flow vane need to be inspected. Heck, based on the rough ride, it could even be a cracked case.

rom what you describe, the problem is much more than a small pinhole. I would not be diving that regulator until the problem was identified and repaired.

 

[beanojones]

(This is a little bit a story about why purge button depressors have been eliminated from gear, and why.)

Seconding the get your gear serviced vote. Have them test dive it if they can.

 

[DA Aquamaster]

An intermittent failure is odd. It is possible the exhaust valve is getting folded over so that it does not seal properly. It is also possible that you have a small leak in the case or diaphragm that causes water to accummulate and you just don't notice it until 10 minutes into the dive.

I know of at least one case where the wet breathing reg was not the problem. This occurred on a dive boat and the clue here was the rusty water dripping from the reg. I inverted the tank and pressed the purge and about a pint of rusty water flowed out. The tank had a significant amount of water in it and also had no dip tube. On further discussion it became apparent the reg had only breathed wet when the diver was in a head down position. If a diver has been south of the border, I often put a faulty compressor and water in tanks at the top of the suspect list.

The other oddity you describe is a wet breathing reg combined with a failure to deliver air.

You can do the following pre-dive checks:

2. Connect the reg to the tank - do not turn on the valve. Inhale softly. You should hear the diaphragm and lever move. Inhale harder - you should still get no air, If you get even a small amount of air or hear a leak, you have a leak in either the diaphragm, exhaust valve, one of the o-rings sealing the openings in the case, a crack in the case or a hole or tear in the mouthpiece. Don't dive the reg if it fails this vacuum check until you get it serviced.

2. Turn on the tank valve. Inhale - you should get a normal breath.

3. Depress the purge button. It should start flowing air with no more than a few millimeters of prepression. If you have to push it more than that to start airflow, the lever is out of adjustment in relation to the orifice and the working range of the valve will be restricted. If this is the case, do not dive the reg.

One downside of fancy flow benches is that techs often do the mechanical flow testing with the reg connected to the bench but fail to do something simple like popping on a mouthpiece and doing a vacuum check.

 

[halocline]

The strange thing about your story, if I'm reading correctly, is that your second stage flooded with water AND wouldn't deliver air on land after the dive, and yet you dove with it the rest of the week and again a couple of weeks later. That's confidence!

The combination of the flooding and the not-working on land is pretty strange. In fact, it's pretty unusual for a downstream 2nd stage to stop delivering air on demand. I would bet something is wrong in the way the lever was set up on the poppet. The flooding is probably a different problem. Sounds like you got a bad rebuild. If that's the case, then you might want to send the whole thing to someone else. If they screwed up the 2nd stage, you don't know what happened with the 1st stage. Since they replaced the yoke nut, you'll want to make sure it was torqued correctly. Apparently there was at least one SP dealer in TX that thought that the yoke retainer recall for the MK20 consisted only of changing the plastic saddle and not the actual retainer.

 

[DA Aquamaster]

Apparently there was at least one SP dealer in TX that thought that the yoke retainer recall for the MK20 consisted only of changing the plastic saddle and not the actual retainer.

That is really scary given that the new retainer, new filter, new filter retainer, new o-ring and new saddle all come in the same upgrade package. A tech would literally have to ignore the heaviest piece in the package to not install the new retainer.

 

[wakeupndive]

Thanks driftwood. Would the torn mouthpiece be visible? It looks intact, though I did not remove the cabletie and take it off the reg (it's actually some kind of fancy thing like a cable tie but more burly).

Muchas gracias mattboy. I did chat with the shop about the reason for the recall and remember them talking about the plastic cover just being an indicator to know whether it had been fixed. he was skeptical about the need for a recall but seemed to understand what was involved. maybe I will have to make the loong trek to the other shop I've been to around here. One more question, what is a poppet?

 

[wakeupndive]

thanks awap- there's no obvious external damage but will ask them to also check for cracks. Now that I am back from the wilderness I'm definitely not planning to dive this reg again before having it repaired.

DA Aquamaster- I really appreciate the list of tests to check things, this is really very helpful as I'd like to learn more about my regulator in addition to getting it fixed. The compressor is a good idea, the diver who provided the compressor asked if my air was ok after the first dive, since I had the reg problem. He said it was a new compressor ("new to us" not "new from the store") and we were going to test it out and see how it worked. However, the tanks were shared among the four divers and I didn't hear of water in the other regs.

 

[halocline]

One more question, what is a poppet?

In this case it's the stem and casing for the soft seat. The soft seat seals against the orifice and forms the valve that opens and close when you breathe. The stem is threaded and is connected to a lever which rests against the diaphragm. When you inhale, you lower pressure in the reg body, collapsing the diaphragm, which pushes on the lever, which then pulls on the threaded stem which draws the seat off the orifice, opening the valve and allowing air in from the 1st stage. It's a delicate arrangement, sort of. If you tried to breathe from the reg and got little or no air, but did get sufficient air from another 2nd stage connected to the same 1st stage, I would suspect something in the poppet/lever mechanism.