Regulator Intermittent Stutter after Service

[buddhasummer]

Well, I'm relieved. lol I guess I'm too used to supposedly trained divers saying ridiculous things that I thought you were one of them. You gotta include a winky face when you do that & I gotta get more sleep so I don't fall for it.

I don't think I'm one of them, considered a wink but thought it would be obvious, guess not for the sleep deprived. Have a good weekend. Cheers.

 

[Joneill]

I don't think I'm one of them, considered a wink but thought it would be obvious, guess not for the sleep deprived. Have a good weekend. Cheers.

It was very obvious to me - no wink was needed!

 

[Sevenrider860]

Thanks for the advice. We took it back to the shop and they emailed this back in response, does it sound reasonable?

Response:

I checked your regulator this morning. The breathing resistance nob was turned ¾ of the way towards harder breathing. I like to leave the adjustment 1/8 – ¼ turn in from counter clockwise for easier breathing effort and less air consumption. At this setting the effort to breath is at 1.” of Mercury versus almost 2” turned inward. The knob basically is there to control a free flow swimming into a strong current or to control a small leak from a high demand lever or worn LP seat. Right now the 2nd stage is very smooth and set to 1” on a Manometer. Thanks.

The explanation sounds reasonable...except for the "less air consumption" statement.

Most regulator second stages are tuned using a value measured in inches of water on a magnahelic gauge, not inches of mercury as indicated. The legend 2nd stage should be tuned to 1.0 to 1.3" H2O with the adjustment knob all the way out (fully turned counter-clockwise)...unless it is a Supreme (cold water model) which is 1.3 to 1.7" H2O. The email would imply that the opening effort would be less than 1" with the adjustment knob fully open. If the regulator is not free flowing with the knob turned all the way out...I think the adjustment is fine.

Most issues I find with the Aqua Lung Legend do not deal with the second stage adjustments, it is the first stage IP (MP in Aqua Lung speak). Most regulators have a manufacturer recommended IP setting of 130 to 145 psi ( 9 to 10 bar). An untrained or uninformed service person will often use that same value on the Aqua Lung Legend...and that is not correct. The Legend has a lower IP setting of 116 to 130 psi (8 to 9 bar).

 

[victorzamora]

(I need to educate myself on ip).

This is simple to do. Buy yourself an IP gauge, specifically one that plugs in to your Low Pressure Inflator port.

What you're looking for is a value in the Mfg-recommended range (typically 130-145, lower on the AL Legends). The "IP" is "Intermediate Pressure" and is what your first stage reduces the pressure to. Your second stage reduces the pressure further (to ambient). There's a soft rubber seat that seals against a sharp metal edge inside of the first stage body, and with time, it can settle or split or misalign or whatever and the IP can go up....this is called "IP Creep." This is the main indicator that something is about to go wrong (besides bubbles). An excessively high IP can cause a properly-tuned second stage to freeflow.

Using the gauge is a piece of cake: Put reg on tank, pressurize regs, plug in gauge, read value. As long as the value is mostly consistent and within the pressure range specified by the Mfg, you're pretty likely good-to-go.

On the second stage: if you unscrew the hose connecting to it and look inside, you'll see either a hex or a flat-head screw. That adjusts how "easy" or "hard" (inches of water or inH2O the LDS quoted you, inHg was a mistake) the reg breathes. Once you get the first stage tuned correctly, you tune the second stage to match. Swapping second stages between first stages "could" be a problem if they're of different IPs, but most fall in the same range.

 

[victorzamora]

Thanks for the advice. We took it back to the shop and they emailed this back in response, does it sound reasonable?

Response:

I checked your regulator this morning. The breathing resistance nob was turned ¾ of the way towards harder breathing. I like to leave the adjustment 1/8 – ¼ turn in from counter clockwise for easier breathing effort and less air consumption. At this setting the effort to breath is at 1.” of Mercury versus almost 2” turned inward. The knob basically is there to control a free flow swimming into a strong current or to control a small leak from a high demand lever or worn LP seat. Right now the 2nd stage is very smooth and set to 1” on a Manometer. Thanks.

Probably just a case of mental flatulence....but: 1.0 inHg would be impossible to breathe.

 

[halocline]

Thanks for the advice. We took it back to the shop and they emailed this back in response, does it sound reasonable?

Response:

I checked your regulator this morning. The breathing resistance nob was turned ¾ of the way towards harder breathing. I like to leave the adjustment 1/8 – ¼ turn in from counter clockwise for easier breathing effort and less air consumption. At this setting the effort to breath is at 1.” of Mercury versus almost 2” turned inward. The knob basically is there to control a free flow swimming into a strong current or to control a small leak from a high demand lever or worn LP seat. Right now the 2nd stage is very smooth and set to 1” on a Manometer. Thanks.

Nothing that they said addressed the issue of an intermittent stutter. They did say 1" of 'mercury' which is a little scary but I guess it's easy to mistake mercury for water....

You said your husband complained about the intermittent stutter on the way home, presumably from your refresher course. Does this mean the stutter happened in the water? Can you further describe what was happening?

I have had some regulators 'stutter' in the sense that the air delivery is not constant and smooth; i.e there's kind of a pulse of air flow. This is usually due to some wear or incompatibility between the lever and poppet. I assume that the legend is a barrel poppet 2nd stage. (it better not be a downstream unbalanced considering it's cost)

It's probably not IP related (that's a first stage issue), but it's still worth checking to make sure IP is stable and in the right range, and it's probably not dangerous.

 

[The Chairman]

New rubber can make some weird noises at the beginning. It often quiets down as it ages a bit. I did have one regulator that made weird noises because of a faulty hose. It was collapsing on the inside. I had taken the second stage off and put it on another reg and the noise disappeared, so I first thought it was a problem with the first stage. Then I moved the hose over and the noise started up again. A close inspection revealed the issue was the hose. 45+ years of diving and that was a first for me.

 

[diverjen]

Wow thank you all for the responses! Super helpful!

There are two issues so that is probably causing confusion. One issue/observation is that my aqualung legend regulator seems to be tuned too liberaly for me. Holy air even when all the knobs are turned to the - position. This happened last time and it doesn't really bother me other than from reading about ip I wonder if I need to tell them please adjust to the suggested "The Legend has a lower IP setting of 116 to 130 psi (8 to 9 bar)"

The other more unsettling issue is that my husband who uses also an aqualung legend regulator had some air pulsating in the pool immediately following service in a scuba review/refresher pool dive. He did not tell me until we where on the way home. We called and they said bring it back in, we did about a day later we got the email response I mentioned.

I will definitely get an IP gauge for my own knowledge/curiosity, etc

For his issue, maybe its the hose and we will just get some new ones to be sure? His hose is two years old but its one of those bendy ones. So maybe it needs an update? That is at least something he is comfortable changing. Let me know if you have other suggestions. Usually after service you can do a free pool dive. Since we paid for a refresher, maybe he can just hop in the pool this weekend and make sure its not ongoing, maybe he could even try a different hose?

I will definitely direct him to this thread, I can't thank you guys enough for all of this information! Happy Diving!

Looking at the printout mine was adjusted to ip 130 and his was adjusted to ip140

 

[Sevenrider860]

On the second stage: if you unscrew the hose connecting to it and look inside, you'll see either a hex or a flat-head screw. That adjusts how "easy" or "hard" (inches of water or inH2O the LDS quoted you, inHg was a mistake) the reg breathes.

You should not adjust the Legend this way...maybe it is more accurate to state that the design engineers do not want you to adjust the Legend this way. The adjustment you describe is used to set the lever height only...there is a Seat/Lever Tool that is used to ensure correct lever height. Once the lever height is set, put the LP hose back on. Your adjustments occur on the opposite side with a 4mm hex key.

 

[buddhasummer]

To add, once you've adjusted "micro adjuster" for cracking effort you should then re check lever height.