Apeks 1st stage diaphragm clamp leaks

[rsingler]

The diaphragm let go blowing out the environmental seal draining the tank in what seemed like seconds.

This is a fascinating occurrence. As you know, a diaphragm reg with no diaphragm is an upstream valve, and remains closed. So what must have happened here is a dislodged diaphragm edge that was nonetheless still intact enough to maintain pressure on the pin hat and keep the valve open. Which makes sense, since the main spring and the pin hat would have clamped the diaphragm center between them, while the edge fluttered away!
Scary! Especially if we can't blame abuse or poor service.

 

[grf88]

The diaphragm had extruded out on one side. The environmental seal was literally shredded. I believe the issue was a failed high pressure seat allowing increased pressure below the diaphragm. The reg was as from the factory with about 30-50 dives on it but probably closer to 30. The reg manual just states "tighten into the main housing until it seats solidly. The joint should be tight but will not set hard due to the soft diaphragm material - don't overtighten."
This was an early issue of this reg and I noticed that subsequent service kits had a different diaphragm. Since there should not be greater than IP pressure plus ambient below the diaphragm then for the diaphragm to dislodge it probably means a seriously drifting IP for this to happen. I understand there have been some issues with high pressure seats during the past few years and maybe that is what has caused this problem.

 

[rsingler]

Ah! The torque phrase (not!) gives away the brand. That always bothered me, but the guy that first taught me reg repair didn't use a torque wrench either.
Needless to say, I believe differently...

 

[Centrals]

The leak on the diaphragm clamp is usually very small(tiny stream of bubble) in the beginning. Once that happened I have the reg serviced by myself.
Bulging environmental seal is also a good indicator that gas has came through from the HP chamber.
Always a good idea to soak the equipment under pressure in fresh water after diving and have a visual check. No such issue for deco regs as they are right in front of me and have ample of free time to check them.

 

[stepfen]

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.

 

[happy-diver]

Here's MY din spanner

Not YOUR din spanner


TAF Don't split your Mk20s in two

You see if you hold the handle about where the helium tank is, perfect torque

 

[rsingler]

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

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.

 

[rsingler]

You see if you hang the Helium tank from the handle about where the helium tank is, perfect torque

Fixed that for you!

 

[happy-diver]

The tank's full man insert's not corroded so it should work

Or will it float and tighten it further

 

[Centrals]

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.

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