halocline
Contributor
The IP fluctuation, including dropping a few PSI after sitting probably has nothing to do with a 2nd stage leak. I suspect that there is a small imperfection on either the piston edge or the seat surface, and this caused the IP to fluctuate slightly right after rebuild. It could even be dust or a hair. IP is the force required to seal off the HP valve, so if there's an imperfection that prevents the seat/piston edge from matching up perfectly, a little HP air leaks into the IP chamber, which pushes up the IP, which then puts more force on the piston until it seals against the seat. If you leave it pressurized overnight, it basically breaks in the seat/piston edge so that it forms a more reliable seal. This is fairly common with the MK10 and MK10+; and atomic 1st stages are very similar in geometry to the MK10+.
You might wonder where that 10 PSI went if there's no 2nd stage leak, and I don't know the answer to that, but it could very well just be settling in the IP gauge itself. Those things are not exactly high-precision devices. But if there was a leak in the 2nd stage, the IP would drop a LOT more than 10 PSI over night. There's just not that much air in the chamber. It would have dropped until the 1st stage didn't seal anymore, then 'burp' back up to a higher IP.
At this point, leave the reg unpressurized for a while and then fire it up, checking IP lockup after tapping the purge several times. If it stabilizes, your seat is broken in. If not, back to the shop for a new seat and a very close inspection of the piston edge. Atomics use the rounded piston edge like the later SP 1sts, and I suspect they can lock up a bit mushy from time to time.
There is a trade-off between performance and lock-up stability with the rounded piston edges. They flow ALOT of air very smoothly, and they last forever. The latest MK25 piston locks up well, but the earlier SP rounded pistons and the stupid SR1 piston can be a bit mushy. There's nothing to worry about if its only a few PSI. I would think that atomic would have designed a great piston edge; they basically designed the MK25. But you never know.
Your 2nd stage purge issue is simply an adjustment that the highly-professional-and-rigorously-trained tech forgot to make or did a poor job with. He needs to adjust the floating orifice better, that will set the lever height correctly and fix your purge problem. I've never been crazy about the floating orifice design, mostly because I'm a cranky old-school guy and walked five miles in the snow to fix regulators when I was a kid. And i liked it!
You might wonder where that 10 PSI went if there's no 2nd stage leak, and I don't know the answer to that, but it could very well just be settling in the IP gauge itself. Those things are not exactly high-precision devices. But if there was a leak in the 2nd stage, the IP would drop a LOT more than 10 PSI over night. There's just not that much air in the chamber. It would have dropped until the 1st stage didn't seal anymore, then 'burp' back up to a higher IP.
At this point, leave the reg unpressurized for a while and then fire it up, checking IP lockup after tapping the purge several times. If it stabilizes, your seat is broken in. If not, back to the shop for a new seat and a very close inspection of the piston edge. Atomics use the rounded piston edge like the later SP 1sts, and I suspect they can lock up a bit mushy from time to time.
There is a trade-off between performance and lock-up stability with the rounded piston edges. They flow ALOT of air very smoothly, and they last forever. The latest MK25 piston locks up well, but the earlier SP rounded pistons and the stupid SR1 piston can be a bit mushy. There's nothing to worry about if its only a few PSI. I would think that atomic would have designed a great piston edge; they basically designed the MK25. But you never know.
Your 2nd stage purge issue is simply an adjustment that the highly-professional-and-rigorously-trained tech forgot to make or did a poor job with. He needs to adjust the floating orifice better, that will set the lever height correctly and fix your purge problem. I've never been crazy about the floating orifice design, mostly because I'm a cranky old-school guy and walked five miles in the snow to fix regulators when I was a kid. And i liked it!
