Freshly serviced regs!

[northernone]

Tldr: Reg freeflowed and frightened into panic a fellow diver. Written from the spectators position.

Wordier ramble:

Was in the water with a random guy who just got his regs back from servicing. I'm naturally sceptical and have seen many freshly serviced regs fail badly on their first "real" dive so I asked before the dive if I could look it over and see how it breathed.

(I like gear and it was one of the shiny legend regs)

My quick once over included:
Slowly pressuring. Slow purge. Fast pressurize, fast purge. Breathed fine on land, wiggle tested it, looked for signs of sloppy service (weird damage or things omitted), finger checked the hose connections, heavy breathed. Wet the reg, blocked exhaust vents and blew positive pressure. Purged system then sucked negative pressure. Didn't do anything in the water or check cracking pressure by submerging the reg.

We dive separately as planned. He's in the water with his buddy while I'm solo diving taking photos.

I hear a bubblecloud going off and look to where I last saw them. Fin that way, find him alone looking wild eyed. Free flowing reg in hand fumbling for his alternate, mask mainly flooded. Finning oddly and jerky in every motion.

I give him a reg and take him by the shoulder strap. Eye contact, give him the breathe sign and ok sign. He calms while I shut down his tank valve. His buddy reappears looking puzzled. I let go of him to feather the valve and smack the reg a few times. Still freeflowing so I shut the valve down to a 1/4 turn and signal to him he is "out of air". He responds correctly. I suggest the buddy shares air and they ascend together. Didn't see them come back down and when I was done my dive they had left the site.

For what it's worth, seemed like a uncomfortable time for him.

Between the lost buddy, catastrophic free flow, panic, lack of CESA and flooding mask it seemed unpleasant.

Lessons learned?

Oh, in hindsight for my own behaviour, I added risk by leaving his tank partially closed to slow the free flow. Not my valve to touch. Second takeaway, would have been better to call my dive and see them safely to shore. The largest piece, underwater reg diagnosis shouldn't have taken place and added unnecessary delays and risks. He needed brought to the surface. Just call the dive.

Also curious what predive reg check I missed in going over his reg that might have caught it.


Cameron

 

[sea_ledford]

Most of the freeflows I have seen on fresh serviced regs were from the seat breaking in mid dive resulting in minor freeflow. Never seen a full blown bubble cloud from that. Purging the reg a few dozen times during service seems to keep that at bay. Underwater you can adjust (if available) the second stage to reduce flow, not the venturi lever,the knob on the end.

As far as pre-check, purge a few dozen times and see if it starts leaking air a bit, then adjust the orifice if necessary.

-Chris

 

[rsingler]

I may have misunderstood your explanation of the check you did out of interest in his "shiny reg", but it sounds like you did a pretty complete 2nd stage check, excepting the cracking effort, as you noted. But just breathing from it without a subsequent hiss suggests that cracking effort too was okay.
So a late freeflow that is resistant to banging and purging sounds more like a first stage problem, with excess IP being vented via the 2nd, as it should be.

My 2¢.

 

[EireDiver606]

How do freshly serviced regs fail ? Poor technician servicing?

 

[rsingler]

How do freshly serviced regs fail ? Poor technician servicing?

It's a straightforward business. Not too complex, but requiring of two things for reliability: experience and precision.
Experience you get by getting good instruction, and maybe making mistakes, but you recover by post-repair testing. Precision you have to have the temperament for. If you're rushed in a busy shop, it's all too easy to nick an o-ring during reassembly. If you skip steps, it comes back to bite you. If you're sloppy, it bites you.

There are some freeflows that are almost unavoidable. If you are asked to set cracking effort at the low end of spec, when the seat takes a set it may begin to freeflow gently. But that's a five minute adjustment, and not catastrophic.

And this could be one of those rare part failures. A HP seat could have a flaw and fail. I've had a HP Seat viton oring with a molding flaw cause a first stage failure a few days into a trip, on first pressurization. It happens.

This oring split like a sandwich, and leaked out the hole where the brass pick now sits. That was a surprise, but you can clearly see the plane where high pressure air divided the oring, probably along molding lines.

I hope the OP finds out what really happened.

 

[northernone]

- snipped excellent content -

I hope the OP finds out what really happened.

Sadly it was a random dive site and random strangers 1200 miles from home. I wouldn't likely recognize him again. But he dove this reg combo:

The site wasn't one likely to deposit sediment in the 2nd stage and nothing felt jammed up... just firehose freeflow. I would agree it seemed like a first stage issue. I was calm while smacking the 2nd stage and there were no momentary improvements or change in the flow rate. (Subjective)

@EireDiver606 I've seen defective parts and a boatload of technician error's in the servicing result in reg failure shortly after service.

...experienced both myself for that matter. I've only serviced my own regs, so I don't even have a large personal sample size.

 

[rsingler]

So since it was a diaphragm reg, if we presume a first stage issue, that limits the possible causes.
In a diaphragm, not much can go wrong, despite the increased complexity of the mechanism. A diaphragm rupture or slip out of position would result in a mass of bubbles outside the reg, and a drop in IP with no 2nd stage freeflow.
A break in the connecting pin would shut the reg down.
That leaves only a catastrophic HP seat failure or balance chamber o-ring leak as a source for increased IP.
These days, with better manufacturing, I'd say the seat probably didn't fail.
However, that 2-006 tiny balance chamber o-ring is a real pain to remove and replace. Aqualung makes a great plastic tool to snag it, but I've seen lots of guys go after it with a steel double hook pick, because the seat for it is so darned tiny. It's very easy to score the inside land of the HP receiver with a steel pick, and that's where my vote lies with this case. It's harder to damage this o-ring on assembly, because it just presses into place, unless the tech was particularly ham-fisted.
High pressure air is now crossing over to the intermediate compartment via the balancing mechanism and raising IP until the second stage freeflows.
Still, a full froth freeflow is a lot of air to get past a scratched land. I would have loved to take that set apart. Maybe it was a second stage problem after all. Something weird like an improperly installed poppet being jammed in the open position after a particularly large lever movement like a manual purge.
There are a limited number of possibilities, but each and every one requires exact assembly and positioning. Not hard to imagine when you are talking about only two valves that give you a 60,000:1 pressure reduction (3000 psi reduced to 0.05psi inspiration effort)!
It's a testament to modern manufacturing quality that we can routinely expect this kind of performance without a second thought, and go venturing into hostile territory depending upon tiny parts under high pressure.

 

[Couv]

Free flowing reg in hand fumbling for his alternate

@northernone Do you remember if the alternate was also freeflowing? If so, that would pretty much convict the first stage. If the alternate was not freeflowing it does not necessarily rule out the first stage, but it increases the odds of the primary second stage the being the culprit. I'm not very familiar with those regs, but it could just be a case where it was tuned "too hot."

 

[northernone]

@northernone Do you remember if the alternate was also freeflowing? If so, that would pretty much convict the first stage. If the alternate was not freeflowing it does not necessarily rule out the first stage, but it increases the odds of the primary second stage the being the culprit. I'm not very familiar with those regs, but it could just be a case where it was tuned "too hot."

Ah, great clarification.

Only the one 2nd was overflowing. I was able to breathe ok off his alternate but it did not feel "normal".

Didn't think to kink his primary hose to see if the freeflow would switch to the alternate. (Just thought of that now)

 

[rsingler]

@couv , you da man! Great diagnostic move!
Okay. Some weird second stage failure, then.
@couv 1, @rsingler 0