Leaky Reg?

[mwalsh787]

Hey Everyone,

This past weekend, I almost had a dive cancelled by what appeared to be a leaky regulator. I would appreciate any diagnostics/advice anyone might have. Let me give you the details...

I have a MR22 Abyss Titanium reg, a Mares Mr12 alternate and a relatively new Aeris Atmos ai 2 with quick disconnect. I blew through a bunch of air when I last dove this setup on July 4th weekend, but I wrote it off to my not having worked out in a few weeks. This past weekend, I went to do a dive off of Myrtle. Upon hooking up to the tank, as always, I took a breath and watched my computer's pressure readout. It dropped 5 psi per breath. The tank o-ring seemed shifty, so I called the DM over and we switched it to another tank. It did the same thing, 5psi drop per breath. He indicated "It's your reg." and was kind enough to lend me his personal reg for the dives (good guy).

Any ideas on what the issue with my reg might be? Any thoughts would be most appreciated

Mike

 

[davetowz]

Take the reg to your LDS and have a tech look at it. Sounds like you have no idea what the problem is.

 

[Scared Silly]

4-5 psi / 3000 psi * 80 cuft = .1333 cuft = 184-230 cu in

Total lung volume 360 cu with perhaps 1/3 - 1/2 with hard breathing 120-180 cu in.

From what you have described I can not say whether it is your reg or something else.

What happened when you used the other reg?

 

[mwalsh787]

Scared, I was a bit flummoxed by the whole thing as well...usually when I do the "breath test", the psi doesn't move. I've read that if it does move with each breath, it may be indicative of a leak. So I figured I would engage others with more experience to see what they thought...

Dave, you're right...no idea...thus my post I will be taking it to a dive shop for a look for sure.

Any additional thoughts or suggestions would be most appreciated!

Mike

 

[Bubbletrubble]

Could you please elaborate on the abnormal reg behavior?
Was the SPG indicating a stable 5 psi drop after every breath?
For instance, after 10 breaths, the AI computer would register a 50 psi drop in tank pressure, right?

Similar to what Scared Silly calculated...
77.4 cuft / 3000 psi * 5 psi = 0.129 cuft = about 3.65 L
That does seem to be rather high based on average tidal volume numbers (0.5 L per breath), assuming a "normal" breath.
Average vital capacity (emptying lungs "completely" and then inhaling as much as you can) is 4.8 L, so 3.65 L is within the realm of possibility...but that's a very "big" inhalation.

Were there any overt leaks from the reg setup or freeflows from the second stages?
If you pressurize the reg setup and then submerge it fully in water, do you observe any unexpected bubbling? (If air is being lost, it has to be going somewhere, right?)
What i.p. was the first stage putting out?
Did the i.p. recovery look "normal" following inhalation?
How confident are you that your AI computer is displaying accurate tank readings?

What is the servicing history on this particular reg setup? (specifically, date of last overhaul or last time someone was monkeying around with it)

 

[herman]

If I am understanding you correcly, the SPG dropped by 5 psi on each breath and returned. If that is the case, it was one of 2 problems. Either your tank valve was almost shut (unlikely since you changed tanks) or you have a clogged reg filter. Since you changed tanks, my guess is the latter.....one other thing I have seen do this is when shops use tape across the face of a valve and a diver forgets to remove it, it will also cause this problem. In any case, it would be a good idea to have a tech look at it.

 

[mwalsh787]

Herman and Bubble,

Thanks for the response I was probably not as clear as I could have been in my description. Thanks for the opportunity to clarify a bit.

The pressure dropped 5 psi with each breath and did not recover. As Bubble indicated, 10 breaths=50 psi loss. I did not end up taking the pressurized rig under water as I was concerned about the safety of diving this setup. The downside to that is that I did not get any observational data such as bubbles, freeflow, etc.

As far as servicing, the unit was last serviced in December prior to a dive. I experienced a strange humming sound, brought it back to the service tech and he fixed it, indicating that it was a somewhat common problem with this reg design. I next dove the unit in May with no problems, and then on July 4th weekend, with what I thought was a rather high air consumption rate. This latest issue (dropping with each breath) happened last weekend.

The Atmos is new. The first dives with it were a pool dive to test it out in March and the one in May. It appeared to function just fine on the May dive and the July 4th dive. That said, I have heard that the Atmos can report a lower than normal (by about 150psi) pressure.

Mike

 

[Bubbletrubble]

Hmm. So it sounds like you've only used the reg setup on 2 dive outings since it was last "repaired." I don't think we can rule out the possibility that a mistake was made by the reg tech.

I could be wrong about this, but it's unlikely that it's either of the two possibilities mentioned by herman. A clogged inlet filter would permit a retarded, but eventually complete, recovery of both i.p. and the pressure being registered by your SPG. If this were the case, I'd expect your Atmos to show a slow creep in psi back up to the original pressure -- but that's not consistent with what you've described. You also swapped out tanks and the problem persisted which rules out the tank-valve-not-being-fully-open possibility.

FWIW, you can use a small bucket of water to help identify any leaks from the 1st or 2nd stages. You just need to hold onto the tank while it's inverted to check on the 1st stage. Get someone else to help you with this. In particular, look for bubbles coming from the 1st stage when you take a breath off of one of the 2nd stages. Please don't throw out your back attempting this maneuver.

To determine whether the Atmos is functioning properly, I'd recommend connecting it to a different reg (known to be working well) and pressurize the system using a tank also known to be working properly. See whether the Atmos displays a decrease in 5 psi with each breath. It shouldn't if it's working properly.

If I were charged with the responsibility of getting to the bottom of this issue, I would swap out the first stage to rule out a second stage problem.
If this localizes the issue to the first stage, then I'd start swapping out parts with an identical first stage known to be working properly...followed by functional testing (paying particular attention to submerging the first stage in water to spot any leaks).

Your 1st stage is a balanced diaphragm design.
I think the most likely problem is that you have a leak somewhere in your system. If the issue is localized to the 1st stage, then it's probably coming from the diaphragm cap/spring chamber area. This issue would be consistent with the following result:
When you do the inverted-tank-in-a-bucket test (with 1st stage attached and pressurized), bubbles will emanate from the 1st stage when you take a breath from one of the two 2nd stages.
If that's what you see, take the reg back to the dive shop, describe the problem, and tell them to fix it. Chances are the reg tech will just do a complete overhaul again. The shop shouldn't charge you for this service since they probably messed it up in the first place.

Probably the easiest thing to do is just take the whole reg setup back to the shop and ask them to figure out what's wrong with it.

 

[redacted]

If there is a leak, the gas is going somewhere. So start with a tub of water and verify that the rig hold air pressure. If there are no visible leaks then you need to judge if the lost gas is being discharged through you exhaust valve along with your exhaled gas. I have had some reg that had some much venturi effect that some gas was going directly from the inlet to the exhaust valve. Try minimizing the venturi effect and see what that does to consumption. Perhaps it is just set up a bit to hot.

 

[LeadTurn_SD]

If there is a leak, the gas is going somewhere. So start with a tub of water and verify that the rig hold air pressure. If there are no visible leaks then you need to judge if the lost gas is being discharged through you exhaust valve along with your exhaled gas. I have had some reg that had some much venturi effect that some gas was going directly from the inlet to the exhaust valve. Try minimizing the venturi effect and see what that does to consumption. Perhaps it is just set up a bit to hot.

Assuming a correctly functioning computer spg (the Atmos does need to be double checked however), the air has to be going somewhere.

So, among everything else suggested: Check the IP on the MR-22.

I dive and service a pair of MR-22 Abyss regs. They are generally well-mannered and bullet-proof, but...

Mares "specs" their Intermediate Pressure (IP) a bit higher than many brands (142 - 148), and the Abyss 2nds are unbalanced classic downstreams. They are notorius "burpers" (through the exhaust port) if the HP seat starts to go. If IP has crept up a bit too much (past 155 psi or so?) they can burp a little extra air at the end of the inhalation cycle. What happens is the 2nd stage demand valve stays open just a moment longer than it should (because the IP is a tad too high) and as you finish inhaling a final little squirt of air is "burped" out the exhaust port. You probably will not notice this on land, and maybe not even in the water, until the IP creeps too high and you notice a bit of bubbling between breaths.

The Mares HP poppet was improved several years ago, maybe in 2005 or 2006, but after your MR-22 Titanium was made.... if it was serviced fairly recently, it probably has the new HP poppet.... but sometimes a new poppet may be defective (it happens) and maybe your IP is "creeping".

Anyway, after ruling out the Atmos as the culprit, you'll need to "find the leak". It should be something simple, most likely.

Let us know what it turns out to be.

Best wishes.