Apeks 1st stage diaphragm clamp leaks

[Couv]

I was about to start a new thread, but saw this one hence I am going to tell my story here.

A couple of dives ago I noticed a small leak from my Mk11 exactly from the same point (leaking diaphragm).
Compared to the one shown here mine is tiny - a couple of hair thin bubbles per second or so. Small but noticeable underwater.

Immediately after noticing the leak, I've ordered the kit to service it but it will take another couple of weeks before I get it. Since it is a pony reg and the leak is quite small I have decided to keep diving it (2 dives a week or so).

This reg was serviced by me in October 2018 and had about 150 dives as my primary reg till June 2020 when I changed it to pony reg. Between June and November 2020 it had about 30 dives as pony reg (fully charged during dives, a drill now and then but other than that not much action). Between November 2020 and April 2021 thanks to lock down I didn't dive. In September 2020 it passed a long leak and IP test (I leave it for 24+ hours pressurized but with valve closed and notice SPG and IP readings at the end). Post lock down before first use I did check it (couv's list - IP checks etc) but the leak was so small that I didn't notice it topside. So the leak probably started during the lock down or soon after it.

Scubapro gives a torque value (35Nm) for the diaphragm holder for Mk11 but I don't have a torque wrench (owning/servicing only 2 Mk11s is the excuse I give myself). The way I tightened it was to pass a long (about a foot - maybe longer) screwdriver through the holes of the holder and use the length of the screwdriver as a level to rotate it. The small vise I have at home was not strong enough to withstand the force I put to it so I had to use a bigger vice I have at work for this. I'd guess that would be pretty close to 35Nm if not (much) more. I will tell you in few weeks when I will be trying to unscrew it.

One thing I was thinking was to try to locate the leak by removing the spring and the diaphragm disk to look inside but I haven't bothered.

Hi @stepfen ,

I probably should not be butting into a "diaphragm first stage thread," but (here is where I butt in anyway) ensure the kit you install is a MK11 kit as the MK17 uses a different diaphragm (thinner) and 2 diaphragm washers as opposed to 1 found in the MK11.

 

[stepfen]

Your diaphragm integrity depends on the counterpressure from the main spring. Looking at the reg unpressurized with the top half missing the adjustment cap and spring will not tell you anything except that the HP seat is or is not leaking. As soon as you pressurize, the area under the diaphragm will pressurize. Depending upon tank pressure and valve responsiveness, one of two things will happen -
a) the valve will close quickly as the pressure lifts the diaphragm up, the pin moves and the valve slams against the orifice; or
b) the diaphragm will blow before the valve closes because there's nothing holding the top half down.

If you're lucky and a) happens (which actually seems like the more likely occurrence) you can see what IP was reached before the valve closed. I'd suspect it won't be very high.

If it is high, then look quickly, because that diaphragm is going to want to pull loose.

Thanks for the detailed explanation Rob. As always to the point. I was guessing that the diaphragm would withstand the force as the pin/disk moves just a tiny bit (less than maybe 1mm if I remember correctly). I forgot though that air is in there pressing the diaphragm too. I might (carefully) give it a try when I will be disassembling it out of curiosity.

Here's MY din spanner

I did try once long tools as levels, weights at appropriate distances etc to get the required torque but things kept moving around so gave up.

Are you sure?
Make sure you have quality field shield.

Thanks for the warning. At least I didn't try to deep the whole thing in super glue to seal it and call it a day

Hi @stepfen ,
I probably should not be butting into a "diaphragm first stage thread," but (here is where I butt in anyway) ensure the kit you install is a MK11 kit as the MK17 uses a different diaphragm (thinner) and 2 diaphragm washers as opposed to 1 found in the MK11.

Back in 2018 when I first serviced that same reg I was puzzled by this 1 vs 2 washers. I did ask and things were made clear by you and Rob back then:
Newbie repairing a Scubapro Mk11, R395, R295 regulator set. Progress report and questions

Thanks for all the info.

BTW service kit hasn't been posted yet! Grrrr

 

[happy-diver]

I did try once long tools as levels, weights at appropriate distances etc to get the required torque but things kept moving around so gave up.

No weights stepfen it's just the feel
bigger tools give you bigger control
of course with a reg box, and a vice
and torque valve parts in their tank

 

[GF99/99]

My recent experience is that one of the more common failure points in Apeks 1st stages (DST, DS4, US4) is that leaks appear between the 1st stage body and diaphragm clamp (AP1473). I have experienced this with several regulators approaching their recommended 2 year service interval. The leaking seal is apparently the diaphram seating, due to detoriation of the diaphragm or loosening of the metal to metal tightened joint of this diaphragm clamp.
How common is this? Do you have any recommendations how to avoid this? Do you use a specific torque for tightening the diaphragm clam when servicing?

This is interesting, I own about a dozen Apeks regs between DST's, DS4's and US4's as well and have never experienced this. Just wondering are you using Apeks diaphragm's or generic? Also what mixes are you using the regs on? reason I ask about mixes is I have noticed with my deep bailout regs high He mixes 70%+ the clear environmental seal will bulge out over time, I think this is from the He seeping through the diaphragm. But not leaks or Champaign bubbles just a puffy environmental seal and only seems to happen with high He mixes.

To answer your questions I dont know if this is very common, I have seen it once on a friends with Champaign bubbles but that was a 4 year old neglected DST. My recommendations are maybe make sure your tightening the cap enough, Also once its on do not remove it and if you do replace with new diaphragm. For torque as happy-diver mentioned TAF seems to be the going torque for the cap. I tighten mine with a full "man grunt" or two

 

[Scuba Client]

Truly don't mean to pick on you, but for others following this thread, ANY bubbles at this location means I'm calling the dive and won't use the reg again until it's serviced.

Just ordered two Poseidon XStream firsts. Gonna swap out for the US4s on my JJ.
I don't need this issue at depth.

You would think JJCCRs would have gone with the Poseidon XStream first.

 

[Centrals]

You would think JJCCRs would have gone with the Poseidon XStream first.

I believe AP valve has been using Apeks for quite a while.

 

[GF99/99]

You would think JJCCRs would have gone with the Poseidon XStream first.

Apeks regs might be the most used regs on rebreathers than any other brand. Nothing wrong with them I think this diaphragm issue that the OP is discussing might be an isolated issue. If it was common then I highly doubt Apeks regs would hold the reputation they do for so many years.

off the top of my head in addition to JJ some other units that use Apeks regs are Kiss, Liberty, Revo, ISC, Triton, XCCR, Fathom all very well know units.

 

[Scuba Client]

Apeks regs might be the most used regs on rebreathers than any other brand. Nothing wrong with them I think this diaphragm issue that the OP is discussing might be an isolated issue. If it was common then I highly doubt Apeks regs would hold the reputation they do for so many years.

off the top of my head in addition to JJ some other units that use Apeks regs are Kiss, Liberty, Revo, ISC, Triton, XCCR, Fathom all very well know units.

I'm sure you're right. A one off incidence shouldn't induce panic. I'm considering buying Apeks DST/ATX50s to replace my Hollis DC1/212s when diving extreme depths. When lockdown subsides.

 

[rsingler]

The observation was just a good excuse for me to shift to Poseidon XStream firsts. I think they are far and away the best designed diaphragm reg on the planet. Their cup seat and ruby ball are unique, as is their flexible Kevlar diaphragm. Some folks diss the integrated OPV, but I've never had any trouble.

But this Apeks diaphragm issue isn't the only complaint that's out there. HP seat failure in high O2 environments has also been noted. Their design is widely imitated to a greater or lesser extent, but this metal to metal clamp has traded prevention of technician torquing error for possible manufacturing variance, infrequent tho it may be. And three or four first or second hand reports in this thread alone is not a one-off problem.
Me, I've never quite understood the level of enthusiasm. Solid design; good manufacturing, but unexciting. The second stage seats indent quickly.
I'm not a hater, but not much of a fan. I've got old ATX100's and all the variants up thru Sapphire, but mostly just for show.
Rant over.

 

[elan]

I apologize for resurrecting the thread. Rob would not MK17 be a good alternative to XStream on an RB?

The observation was just a good excuse for me to shift to Poseidon XStream firsts. I think they are far and away the best designed diaphragm reg on the planet. Their cup seat and ruby ball are unique, as is their flexible Kevlar diaphragm. Some folks diss the integrated OPV, but I've never had any trouble.

But this Apeks diaphragm issue isn't the only complaint that's out there. HP seat failure in high O2 environments has also been noted. Their design is widely imitated to a greater or lesser extent, but this metal to metal clamp has traded prevention of technician torquing error for possible manufacturing variance, infrequent tho it may be. And three or four first or second hand reports in this thread alone is not a one-off problem.
Me, I've never quite understood the level of enthusiasm. Solid design; good manufacturing, but unexciting. The second stage seats indent quickly.
I'm not a hater, but not much of a fan. I've got old ATX100's and all the variants up thru Sapphire, but mostly just for show.
Rant over.