Regs serviced. now what?

[scagrotto]

id make sure it doesnt leak/ make noise when you breath off it before leaving the shop.

Make sure you test it on a full tank, and not one that's got 900PSI. Many years ago I picked up our regs after they had been serviced, and they seemed fine in the shop. A little while later my wife hooked hers up on a boat, and when she opened the tank valve it whistled like a boiling tea kettle. Back at the shop they claimed that any problems would show up with fairly low pressure, but it was pretty easy to stick it on the tank next to the counter and then a full one from the back and improve their knowledge base (assuming they really believed 900 PSI was adequate).

Of course in hindsight it's pretty obvious that a malfunctioning reg might prevent flow at 900 PSI, but not at 3000. IIRC, it was a pretty minor defect in the piston. Maybe it got missed or maybe it was damaged during servicing.

 

[Couv]

This question comes up often enough so the Usual Suspects wrote this checklist:
http://www.scubaboard.com/forums/regulators/346813-regulator-inspection-checklist-rev-7-a.html

 

[redacted]

Make sure you test it on a full tank, and not one that's got 900PSI. Many years ago I picked up our regs after they had been serviced, and they seemed fine in the shop. A little while later my wife hooked hers up on a boat, and when she opened the tank valve it whistled like a boiling tea kettle. Back at the shop they claimed that any problems would show up with fairly low pressure, but it was pretty easy to stick it on the tank next to the counter and then a full one from the back and improve their knowledge base (assuming they really believed 900 PSI was adequate).

Of course in hindsight it's pretty obvious that a malfunctioning reg might prevent flow at 900 PSI, but not at 3000. IIRC, it was a pretty minor defect in the piston. Maybe it got missed or maybe it was damaged during servicing.

Could you expand on the idea in red? How could that happen?

Yes, it is a good idea to test a 1st stage at the maximum pressure it will see to verify that HP o-rings are doing their job. A piston stem o-ring could extrude and leak at 3000 psi but be just fine at 900 psi. The 900 psi should be fine for LP seals and the 2nd stages.

 

[scagrotto]

Could you expand on the idea in red?

I forget the exact nature of the problem, or if I ever even knew the fine points. To my thinking "extrusion" only applies to the o-ring being forced into a space around the piston, and wouldn't be caused by a defect in the piston. I assume scoring on the piston stem could allow air flow between the piston stem and o-ring without displacing the 0-ring. Perhaps it was a problem with the piston stem mating with the valve seat. As I recall I didn't see an obvious defect in the old piston, but the leak was extremely obvious.

Bottom line is that putting the reg on a full tank and breathing from both 2nd stages is as close to testing under actual diving conditions as you can get while standing at the counter of a dive shop, so that seems like a good first step in checking when you pick up a freshly serviced reg.

 

[redacted]

I forget the exact nature of the problem, or if I ever even knew the fine points. To my thinking "extrusion" only applies to the o-ring being forced into a space around the piston, and wouldn't be caused by a defect in the piston. I assume scoring on the piston stem could allow air flow between the piston stem and o-ring without displacing the 0-ring. Perhaps it was a problem with the piston stem mating with the valve seat. As I recall I didn't see an obvious defect in the old piston, but the leak was extremely obvious.

Bottom line is that putting the reg on a full tank and breathing from both 2nd stages is as close to testing under actual diving conditions as you can get while standing at the counter of a dive shop, so that seems like a good first step in checking when you pick up a freshly serviced reg.

When a defect appears in a piston that has been in service, it is almost always because of a service error either in the handling or assembly. Hopefully your tech meant an o-ring (or HP seat) problem and not an actual piston problem. I assume the problem was repaired at no additional charge.

 

[3D diver]

Bill,

I try to give 'em a few breaths in the shop when I take delivery. Since we're shore divers, other issues will likely reveal themselves fairly quickly on the surface swim and initial descent. Silly me, I've never really taken any additional precautions (or had any problems).

EDIT: Actually let me modify that a bit...shops will often neglect to record which hose goes where, so I do double check where my regs and inflator hoses are attached and reconfigure as needed.

 

[scagrotto]

When a defect appears in a piston that has been in service, it is almost always because of a service error either in the handling or assembly. Hopefully your tech meant an o-ring (or HP seat) problem and not an actual piston problem.

When we picked up the reg we also got a spare piston. They didn't even hint at asking us to pay, and I just assumed they billed Scubapro for the piston and ate the labor cost for getting it right on the 2nd try.

 

[redacted]

When we picked up the reg we also got a spare piston. They didn't even hint at asking us to pay, and I just assumed they billed Scubapro for the piston and ate the labor cost for getting it right on the 2nd try.

It would appear to me that it was probably damaged during service as the leak you describe (supply pressure sensitive) is unlikely to occur in normal use due to a piston problem (O-ring or seat problem - yes). During service, it is important to handle the piston very carefully to avoid damage to the shaft o-ring sealing surface and HP seat sealing surface. A drop (it does happen) can easily damage the HP seat sealing surface putting the piston into retirement. Sometimes, a little artful use of light abrasives can repair such damage but that is not something I would expect a shop tech to be doing. So, you might want to consider that returned part as defective unless you can repair the problem.

It sounds like your shop handled the problem well. Some might try to charge the customer for such repairs. I am a bit surprised they returned to part to you.

 

[scagrotto]

I am a bit surprised they returned to part to you.

Maybe just habit, as I always got back all of the routine parts. The old piston is long gone, and even though I didn't see any obvous defect I certainly wouldn't have tried to use it. Despite being mechanically inclined, that amount of playing with my regs isn't anything I've undertaken. Everybody makes mistakes, but I figure there's a lot of sense in leaving service of life support stuff to people who do it on a regular basis. Accidentally damaging a sensitive part and not noticing isn't something I'd hold against them. I'm more inclined to fault them for telling me that any problems should show up at 900 PSI. Most of them, sure, but (and to be fair, this is also 20/20 hindsight for me) getting as close to the real world situation is obviously the most sensible strategy.

 

[drbill]

Serviced? OMG, regs need to be serviced? Now you tell me.

Seriously, all I do is a long shallow dive after they are serviced (or several) to test that they are working right. Then I may do a few deep dives with a pony attached in case.