10 bar overnight pressure loss on a freshly rebuilt MK10+

[mr_v]

Howdy folks!

I have a freshly rebuilt pair: MK10+ and G250.

They breathe like a charm and hold IP without any issues. I left the first stage charged overnight but with the valve turned off. Over 12 hours, I lost about 10 bar while IP was still holding as expected. What may be causing this? Is this expected? G250 is tuned and had the adjustment knob all the way in - no observable leaks in water before I went to bed.

Side note, when I fully depressurize the first stage and attempt to take it off the tank, it feels a bit tight, like if there was some pressure still there, but the gauge reads zero. The DIN fitting o-ring protrudes every time I take the first stage off the tank... Any ideas?

Thank you!

 

[grf88]

I don't have an answer for the first part but it is quite common for the high pressure hose to be slow to release all pressure due to the orifice. After depressing the purge wait a few seconds and press again before removing the first stage.
Edit: just noticed you said with valve turned off. You realize it would only take a miniscule amount of gas loss to drop the pressure in the first stage 15 bar.

 

[scubaozy]

Press the purge while removing the 1st stage. Do a bubble test to your system for problem #1.

 

[Tanks A Lot]

This sounds very much like air gets trapped "behind" your DIN connection O-Ring. Even when depressurized, air can remain behind this O-Ring, making the connector hard to remove.
Some manufacturers had such big problems with this in the far past, that a small hole was drilled behind this O-Ring to alleviate the issue. A wrong sized O-Ring can let air get behind it and then trap the air in this area.

Not being too familiar with the MK10+ in particular, if it follows the rest of ScubaPros sizing, a BS111 O-Ring should do nicely in that area.

This would however not explain the leakage of 10 bar. Submersing the whole thing incl. first stage should solve this for you though. 10 bar overnight is pretty much nothing though, so you may just observe a small bubble every now and then.

The attached pdf does not apply directly to your situation, but may convey what I mean a bit better.

 

[mr_v]

Second problem solved and thank you, @Tanks A Lot. It was a user error - I was experimenting with different o-ring sizes as I did not like either 112 or 111 and left 112 in the reg w/o replacing it.

First issue - I have no idea... I watched the reg for 3 hours before going to bed and no pressure dropped. The reg was tight in the water - no bubbles. Will re-inspect.

 

[Kupu]

Looking for a solution to a 10 bar loss over 12 hours illustrates how thorough a DIYer can be compared to the job done during an average authorized service. Since IP holds solid, I would consider the job done and monitor the regulator health with use & time as normal.
But it will be interesting to hear the cause, if you do find anything.