Unexpected IP drift in a newly-serviced first stage

[rsingler]

(Split off from another thread where the content wasn't relevant)...

I brought my sealed, recently serviced T2 and T3 on my bucket list trip to Raja Ampat two months ago. As is my habit, I ensured that both first stages had crisp lockup after service and sealing with Tribolube.
The trip was a liveaboard where our gear was stored for us and our setup was done by the crew. It was the exact opposite of my preference that no one touches my gear but me. But to have insisted would have been impolite and inconvenient, as the gear locker was at the opposite end of the boat. But the crew was happy to accommodate us as we tinkered with our setups.
After 12 days and 39 dives, we came home and my wife's T2 was just the way it was when we left town. But my T3 now has 6psi of drift after only 39 dives!!!
For a reg with a 300-dive, 3-year service interval to have new 6psi drift after only 39 dives is really upsetting. It just goes to show that you should check your IP before the first dive of any long trip.
It's been killing me to wait, but I'm going to open up that reg during the May Reg Tech Seminar as a real-world diagnostic adventure. Speculation as to the cause is my reason for posting.

 

[johndiver999]

You are looking for speculation? I'll try. The wife; she did it- not sure how, but she wants to keep you busy and out of her hair.

 

[BoltSnap]

You are looking for speculation? I'll try. The wife; she did it- not sure how, but she wants to keep you busy and out of her hair.

Reading Rob's posts, I am imagining him pacing back-and-forth in his bedroom all night "speculating" about the drift waving his arms and screaming "WHY, WHY?"

 

[Bigbella]

I'd guess that it was the product of accumulated schmutz or other particulate matter from an onboard compressor, getting past the filter, affecting the piston / seat; and that your wife simply lucked out.

I've seldom seen well-maintained compressors on live-aboards, regardless of locale, and have generally rebuilt anything that I had used while on long trips, just on principle.

In Mexico, I had been in the habit of servicing my regulators every six months, after witnessing the interior of a seventy-two that had looked like something from Rancho La Brea -- and reason number-one why we kept a once sizable baggie of sintered filters on hand . . .

 

[-JD-]

It's been killing me to wait, but I'm going to open that reg up during the May Reg Tech Seminar as a real-world diagnostic adventure.

I belive they call that "setting the hook." Now I HAVE to audit ...

 

[Johnoly]

.... Speculation as to the cause ...

I'd vote that it is a very tiny nick in the seat oring. The assembly lube hid the problem for a small amount of time, but the repeated cycling wiped away just enough of the lube to reveal the creep. A possible oring manufacturing defect that wasn't caught at the factory. I won't bet the spring or piston because I know how close you would have inspected those. Please be sure to re-post when a tear-down is done and the issue found !!

 

[Bald Wookie]

If on a liveaboard - Tanks in open, salt/water on valves, not blasted/cleaned before 1st stage attached, salt crystals onto piston, knocking down knife edge?

 

[rsingler]

If on a liveaboard - Tanks in open, salt/water on valves, not blasted/cleaned before 1st stage attached, salt crystals onto piston, knocking down knife edge?

VERY common. Probably the single most common cause of mushy lockup in a piston.

In a diaphragm, possible - but will be more surprising because there's less angular change in the jet of gas coming from the tank inlet.
Can't wait to see...

 

[The Chairman]

Drift or static increase?

If it's drifting, or creeping, it won't be limited to 6psi.

If it's just increased by 6psi and holding, well that's pretty normal. O-rings have finally set. If you're not experiencing a freeflow, I would just have fun and dive it.

 

[p_kos]

Drift or static increase?

If it's drifting, or creeping, it won't be limited to 6psi.

If it's just increased by 6psi and holding, well that's pretty normal. O-rings have finally set. If you're not experiencing a freeflow, I would just have fun and dive it.

For a mere mortal that may be acceptable but this is @rsingler you’re talking to.