Mk2 or mk10 for deco bottle

[Mobulai]

I had to go back to my manuals to figure out what I was talking about too... it's been a few years. It must have been an incorrect o-ring that was put at the tip of the piston (22 in the mk2 diagram). I was thinking it was part 41 below, but that wouldn't block the HP port.

View attachment 870118

But as I said, it was a hack job in the first place.

By the look of that Piston in the schematics, this is no mk2; it’s either an mk20 or 25 (essentially the same reg with one difference in the HP seat carrier that’s all)
The #41 oring here is a special feature of the mk20/25 pistons, its has to do with the bushing right above and it being a composite piston made from multiple parts assembled together — but I’m not that knowledgeable about it, I have read previous posts by @halocline that got me to get the basics; a quick search can reveal them if you wanna read about it

It has no equivalent in the mk2 (afaik); the mk2 is a flow-by not flow through, no orifice mid piston shaft, so it’s a straight solid block (not that I ever opened/own one actually)

The #22 in the mk2, looks (I’m guessing) like the HP / IP separation barrier (#19 in the mk25, or #9 for the mk9/10 that @rhwestfall posted), and would be a place for a bad leak indeed
Edit: ok its not a HP/IP barrier, it’s ambient (water)/IP barrier, basically leaks into ambient chamber when it’s broken

 

[Mobulai]

Maybe that #22 orings function is clearer in this cross section view