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Phoenix HP leak issue

Posted: Fri Sep 11, 2020 3:32 pm
by ScubaLawyer
This was my first Phoenix that I got in 2010. A year or so ago I bought the overhaul kit and replaced all the seals and o-rings. The reg worked beautifully for many dives until about a week ago when I suddenly started getting a HP air leak. I narrowed it down to a one-sided high-flow stream of air escaping from the area of the first stage to body connection. The Phenolic gasket looks to be in great shape and the 1st state and body were tight and secure. No air was escaping from the 2nd stage (HPR). The Hookah port was tight and secure. The port plugs are all fine. I backed out the hex-nut all the way so it should just be locking up when I turn on the air, but the leak did not stop. I also checked my tank o-ring and the problem repeated no matter what tank I put the reg on.

All I can figure is that something is causing the HP seat pin to be depressed (although there are no visible culprits) or there is something wonky in the 1st stage. I haven’t taken the first stage apart yet. Just wanted to get some input from the experts as to what I should be looking for.

Hopefully it will be something dumb that my brain could not fathom.




Re: Phoenix HP leak issue

Posted: Fri Sep 11, 2020 4:14 pm
by antique diver
Sounds like you are describing the air as leaking out between the first stage and the main body. I have heard of this just recently from another Phoenix user using the same Phenolic gasket. Makes me thing that the threads are bottoming out on each other before the gasket is fully compressed.

Better bet is to use a nylon gasket if it is a little thicker and if you have it available. I heard from the other party that the nylon ones may not be available at this time.

So here's a strange little trick that may be worth a try. I have done this in a totally different HP fitting where the copper gasket was not fully engaged before the threads ran out. I put two gaskets in place together, and problem was solved.

This may not work in your case, but will help diagnose the issue either way: If you don't have a nylon gasket try putting two Phenolic ones in place with a very slight coat of silicone grease on all the flat surfaces, and snugly reassemble the first stage to the body. Test for external leak at high input pressure. Let me know what happens.

Re: Phoenix HP leak issue

Posted: Fri Sep 11, 2020 6:20 pm
by ScubaLawyer
Mystery solved (I think). Broken spring behind HP seat. Still not sure why air was escaping at the 1st stage/body connection but seems to be holding after I replaced the spring and reassembled. Never had that happen before. Can't remember if I used an old spring or a new one when I rebuilt the reg last year. M

Re: Phoenix HP leak issue

Posted: Fri Sep 11, 2020 6:33 pm
by antique diver
Glad you have resolved that. The only thing I can think of is that as the hp seat leaked air (because of broken spring) into the intermediate pressure chamber that pressure climbed just enough to force its way past a marginally sealing gasket before opening the second stage seat. ??? That gasket normally is just holding intermediate pressure from escaping, but there is always pressure there when tank pressure is applied to reg inlet. With the seat leaking, the high pressure inlet air into that area overcame the sealing ability of the gasket... maybe because it was too thin, or first stage not torqued tight enough to effect the sealing ability. ???

BTW, I have not seen a broken HP seat spring before, but obviously it can happen.