MK17 Scratching my Head on this one.

[Scubadude_LA]

Haven't had a chance today to look at it again.
This rig has no spg or hp hose, it's a dedicated rec rig and has a transmitter on the hp port. I have an SP d400 second and a necklaced hog, I've purged both to troubleshoot, also manually breathed them down.
I have the issue with both the white oring and also with a brown viton. Using the standard 112 oring size.
All parts took an extended ride in the ultrasonic last night.
I'll post my findings.

 

[redacted]

I'm pretty sure scubapro uses a 111 rather than a 112.

 

[Scubadude_LA]

I feel like a wingnut... Awap, you were right, UnderH2Oman, no I'm not using the correct oring. I still don't understand the mechanics of the residual pressure but whatever for now.
I pulled the DIN oring included with the MK17 service kit out and it is a 111 not 112.
The polyurethane and viton rings I was using were both 112s.

I included a pic of all three orings (the SP ring to the left and the 112 viton and poly to the right) for future reference.




Thanks for all of the responses, this was a great help, 24 hours later I'm back in business with a very clean and lubed reg.