Regulator issues after servicing

[halocline]

After a few boat dives, I noticed the second stage hissing at the end of the dive - not a full free flow, but definitely leaking air. On the dives prior to that, I was also blowing through air like I’ve never done before . I expected to use more air than normal since I’m new to drift diving, but not to this extent. Additionally, I found that the work of breathing was much harder at around 60ft than I’ve experienced before the regs were serviced, with the adjustment knob fully open.

There are a couple of things here. First, if the 2nd stage(s) are leaking at the end of the dive but not the beginning, and it happens on subsequent dives, that indicates some IP creep.

Using more air shouldn't have anything to do with the regulators unless you are leaking a substantial amount. Although if you are anxious about the performance of your regs (understandable if they're leaking) then your breathing rate will likely increase. That's the only connection.

WOB harder at 60 feet than before is a little contradictory with the IP creep, because creeping IP should, if anything, increase air flow (sometimes to the point of free flow!). But, assuming your perception is real, that WOB is increasing at depth, that almost certainly has to be a 1st stage issue. What it means is that for some reason, the 1st stage is not compensating efficiently for depth, and as a result, when you take a breath at 60 ft, IP is dropping further under demand than it does at the surface. That means the 2nd stage would be getting less depth-adjusted pressure and your cracking effort would really increase. All 1st stages have to work harder at depth to supply stable dynamic IP to the 2nd stage, but obviously they are able to do so when working correctly. I don't think this is a sealed 1st stage, is it? If so, that mechanism is probably where I'd start, assuming the IP was stable over time in the shop.

That's probably more than you wanted to hear. Here's the simple solution, find a repair technician that knows what he's doing, bring him (or her, they do exist, lol) the regulator, and ask for a thorough inspection. That would include leaving the reg pressurized for a few hours and making sure there is no IP creep.

A long time ago, I went on a Cozumel trip with a newly serviced regulator that I had bought fresh out of certification class. The reg performed terribly, and that was the beginning of me learning how to work on my own regs. I'm a fairly mechanically inclined person, and it's worked out really well for me.

 

[halocline]

One other thing I forgot, (Couv would have thought of this, RIP) since the Mikron is a diaphragm 1st stage, if there is an issue with the balancing, then IP would be higher at lower tank pressures. That could explain both the free flow at the end of dives, and could contribute to the higher WOB at depth IF you are following the typical Cozumel dive profile where you descend quickly to the deepest part of the dive and then make your way up slowly. In this case, the depth is irrelevant, its the higher tank pressure that is causing higher WOB because IP is lower. You can have a competent tech check IP at both 3000 and 500 PSI and compare them. They should be about the same.

 

[uncfnp]

Did I misread something? I understood that the hissing was noticed toward the end of a series of dives, not at the end of each dive? Could the OP clarify?

Also, if it was an issue with the first would not the ABS octo also be leaking (I am not familiar with the ABS).

 

[James79]

Also, if it was and issue with the first would not the ABS octo also be leaking I am not familiar with the ABS).

If it's an IP creep issue, the second stage with the lower cracking pressure is most likely to leak first (balanced second stages may alter that). Regardless, once one leaks it is relieving the excess pressure.... so the IP never gets high enough to cause the other second stage to leak.
My biggest contra-indication of IP creep with it is that most people turn on the tank and leave it on until they splash. In that event, an IP creep issue should manifest before they splash.... the longer without a breathe on the reg, the higher the IP gets a chance to creep to.

Respectfully,

James

 

[halocline]

Also, if it was and issue with the first would not the ABS octo also be leaking I am not familiar with the ABS).

Not necessarily, whichever 2nd stage is set more lightly would likely start to flow first, which relieves the IP creep that is causing the flow. I have seen full on HP seat failures where both 2nd stages just start blasting air. If the primary 2nd is balanced and as such is presumably less reactive to IP changes, then you would think the unbalanced octo would flow first, but IME it doesn't end up always being the case.

 

[halocline]

If it's an IP creep issue, the second stage with the lower cracking pressure is most likely to leak first (balanced second stages may alter that). Regardless, once one leaks it is relieving the excess pressure.... so the IP never gets high enough to cause the other second stage to leak.
My biggest contra-indication of IP creep with it is that most people turn on the tank and leave it on until they splash. In that event, an IP creep issue should manifest before they splash.... the longer without a breathe on the reg, the higher the IP gets a chance to creep to.

Respectfully,

James

Beat me to it!

With regards to the idea of leaving the tank on for the boat and why doesn't that result in flowing before the dive, I understand your point but I think that in some cases, it's subtle enough so that 'creep' is mixed in with 'drift' or other instability in lock up. So repeated cycling of the 1st stage doesn't fix it. That, plus the rise in IP over the supply pressure range on a diaphragm 1st with balancing problems, might be what's going here. It's just a guess.

 

[James79]

Beat me to it!

With regards to the idea of leaving the tank on for the boat and why doesn't that result in flowing before the dive, I understand your point but I think that in some cases, it's subtle enough so that 'creep' is mixed in with 'drift' or other instability in lock up. So repeated cycling of the 1st stage doesn't fix it. That, plus the rise in IP over the supply pressure range on a diaphragm 1st with balancing problems, might be what's going here. It's just a guess.

My inner nerd really just wants to get my hands on the reg set to troubleshoot, lol!

 

[arcie]

THANK YOU all so much!! I truly am blown away by the generosity. I'm going to go back and address some of the questions later, but just wanted to say thanks now. And will definitely give an update later this week after I follow-up with the dive shop.

 

[Litefoot]

Wow, she asked how to change the oil, but now she knows how to rebuild the engine! This is what I love about SB. If you ask a question, you better be ready to take notes.

 

[rsingler]

after I follow-up with the dive shop...

When you go in, ask them to test the gear BEFORE they service it again.
1) what was the first stage intermediate pressure?
2) did it drift and lock up at a higher pressure?
3) did it continue to creep?
4) what was the second stage cracking effort

And before you take it in...
does the lever rattle when you shake the second stage unpressurized? You can probably see the lever thru the mouthpiece up against the diaphragm. Is it loose when you hold it over your head and look up, and then turn the reg over?

Yeah, your questions will perhaps upset them.
But then, I think they might deserve it.