Scubapro S600 free flow

[mick allein III]

Ok I'm going to put it back on the gauges and recheck everything. I will post later and let you all know


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[rhwestfall]

A completely different brand reg, but I have been chasing one doing similar things to my buddy. I have not had it in my possession to really play detective on, but to me it seems the failure to hold tune is because the seat is not been cycled enough.... There has been some IP stability issues that seem to be working themselves out but only time will tell. Honestly, it seems to be "break-in"...

FWIW - I also own SP 109/156, G200b, G250v, & S600 seconds that I service & tune....

 

[Couv]

.....and again. The Master mentioned in post #2 the balance chamber. It's a funny onion so if you did not adjust it correctly you may have to start from scratch.

 

[mick allein III]

Right now I have the first stage hooked up to a good known 2nd stage. If I can verify that the 1st stage IP is stable and in range then I can be sure the problem is in the 2nd stage.


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---------- Post added December 31st, 2014 at 05:12 PM ----------

The mystery continues. I clearly have a 1st stage problem. The IP is stable for an hour charged at 500 psi. When I tested and charged at 3000 psi it stopped at 140 but climbed to 148 over 30 minutes. I took apart and made sure seat was clean and seated. Knife edge looked fine. Any ideas? Should I put a new kit in? Frustrating


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[Couv]

If you did not reinstall the hp seat in exactly the same position, then you may very well have double engraved the soft seat. This would require a seat replacement. If the seat does not solve the issue, and you are sure the knife edge is perfect the next thing I would suspect is the HP stem o-ring is extruding. If it is the wrong hardness (85-90) that could be the issue. Lack of lubrication of the piston stem and o-ring could also cause it to drag. However, both of these issues usually cause high IP rather than creep.

I vote for the low hanging fruit first. Replace the hp seat and see what you have.

 

[Fishpie]

The o ring around the second stage orifice is often "forgotten" to be changed at service time and will eventually begin to leak.

 

[mick allein III]

I replaced seat yesterday same thing. Today I took it all apart and rebuilt it. I think the problem was in the bushing system and or lubrication on the seat. The knife edge looked perfect. Regardless, at both 3000psi and 500psi the IP was stable at 138 for over an hour. It is behaving similar to my othe MK 25s. I'm going to declare it fixed. This should make tuning the s600 easier. I'll make sure that's working right tomorrow. Since I'm learning if anyone can go back up to post 6 where I describe my problem and explain how IP creep may cause this type of free flow I'd appreciate it.


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[Couv]

In all likelihood the amount of IP creep you've experienced will not cause the type of intermittent freeflow problems you described in post 6. This is especially true of air balanced second stages like the s600. An unbalanced second stage is a bit more susceptible to IP changes, but still not at the level you described. However, it is good practice to insure you have a stable IP before adjusting a second stage as you will never be able to get a gnat's ass close to perfect adjustment without a stable IP. That is why we emphasize STABLE IP FIRST. You have to start somewhere, a stable IP is the place to start as the "hotter" the cracking pressure, the more important stable becomes and you have to rule high IP out before continuing.

Getting back to the question "how does IP affect cracking pressure?" Think of of this way. When you adjusted your second stage to say an IP of 130psi essentially you increased the spring pressure pushing on the seat just enough to stop the flow of gas coming from the fist stage (130psi.) If the IP creeps then more spring pressure will be required to hold back to greater amount of pressure. In the case where IP creep does cause a freeflow, the second stage is acting as a pressure relief valve.

This is all well and good and explains the relationship between IP and cracking pressure; but the real problem could be in the second stage: a split or rolled seal in the balance chamber like Awap suggested, a bad o-ring on the adjustable orifice (Fishpie), an engraved seat (Tbone) you may as well do a complete second stage rebuild. FWIW a few other things to look at: lever sticking, dirty air barrel, second stage orifice defective, bad spring, etc. If you have to time try your best to determine the exact cause by replacing suspect parts one at a time-this will give you a better understanding of how each component does it's job.

Good luck; looking forward to your findings.

Couv

 

[mick allein III]

Couv I appreciate your response. I like the idea of putting in 1 piece at a time. I notice today that the IP creep returned when I left the s600 with the micro adjust all the way turned back. The reg is driving me crazy, but I am learning a great deal. Thanks again for your help. I'll keep you all posted.


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[Couv]

You are finding out the hard way that a second stage (by acting as a pressure relief valve) can cause you problems when trouble shooting a first stage. Install a first stage pressure relief valve (for safety) and remove all the second stages. https://www.divegearexpress.com/regulators/regacc.shtml

Solve the IP problem first or find a first stage with a known good IP before continuing.

BTW: You did remember to cycle the first stage after replacing the seat, right?