problem with DACOR XL second

[emoreira]

Hi, I have an old DACOR XL second stage working in one of my regulators.
This second works OK, but it has a small problem that puzzles me.
When I'm upside-down, with this second in my mouth, if I'm not breathing, this second starts bubbling, not so much, not like in free flow, but a little stream of bubbles.
If the second is not in my mouth, no matter how it is, it's not bubbling.
I have been using this second as octopus in my main reg set, but now I've replaced it with a new octopus.
What could be the reason for this bubbling ?
Thanks.

 

[tbone1004]

all second stages of this style will do this if you are upside down.

basically what is happening is the exhaust diaphragm is letting some air out, when it does that, it creates a vacuum inside of the housing and that depresses the lever to feed it with more air to equalize. Once it is equalized, the diaphragm leaks a bit more out and the cycle continues. According to the regulator, it is exactly the same as when you inhale against that diaphragm so it doesn't know or care that it is going through the exhaust diaphragm instead of into your lungs.
When the second stage is out of your mouth, it is flooded with water so it can't create the pressure differential

completely normal behavior

 

[emoreira]

Thanks for your comment tbone, but the main second is a DACOR Pacer Totally Balanced, which is almost the same design and does not have this issue.

 

[tbone1004]

Thanks for your comment tbone, but the main second is a DACOR Pacer Totally Balanced, which is almost the same design and does not have this issue.

how new are the exhaust diaphragms? Exhaust diaphragms are one of the things that many people ignore during maintenance and if it is a little sticky at all or is a bit stiffer, then it may not open as readily

 

[emoreira]

Now makes sense. Thanks

 

[herman]

Setup of the second stage will also determine if this happens or not. The Pacer may be set a little bit tighter (slightly higher cracking pressure). It would not take much and it's very unlikely you would notice the difference.
For what its worth, I have no clue why Dacor put "balanced" on the Pacer second stages but they are not. Very few Dacor second stages were actually balanced.