adjusting regulator by submerging reg ?

[idive2]

I recently posted on the second stages needing to be adjusted with first stage and someone posted
a method of submerging reg in water and watching bubbles and measuring something ? It sounded like
a measurement was taken from surface of water to location on reg ? I'm going to have an old conshelf
21 first stage serviced soon and will be using it with a conshelf XI second stage. Will factory setting of
intermediate pressure on the conshelf 21 first stage be similar to the pressure that the conshelf XI second
stage would be using ? If I'm following this bubbling thing right on the second stage what part of regulator
would I be measuring to ? Thanks for any suggestions or advice you may offer.

 

[Zung]

I'm not sure I really understand your question. If you want to measure/adjust the cracking pressure of a second stage, I much prefer a manometer you can rig yourself for $2.

To use it, just stick the long end of the piping in the corner of your mouth, suck on the reg, and read the difference between the 2 columns of water: that's your cracking pressure. Usually, 1 to 1.5 inch is good. And your second is also adjusted to the IP of your first.

 

[idive2]

Okay, I think I was misunderstanding what I may have read previously. I was thinking someone was measuring
the distance from top of water to when reg started bubbling or something along those lines. I suppose a slight variation
of intermediate pressure from first stage would be taken care of with the adjustment of second stage being done afterwards.
Thanks for the illustration and the explanation.

 

[Zung]

The alternative method is to immerse the second mouth piece up until it starts flowing, then measure the distance between the surface and somewhere along the cover to get the cracking pressure. It's a bit harder to put a number to it.

No matter which one you choose, you should set the IP first (120-140PSI), then you set the cracking pressure.

 

[spectrum]

Yes, you just gently lower the regulator into a basin of water. Keep the mouthpiece up and the diaphragm parallel to the water surface. The diaphragm depth when it cracks is the cracking pressure in inches of WC.

Pete

 

[DA Aquamaster]

Yes, you just gently lower the regulator into a basin of water. Keep the mouthpiece up and the diaphragm parallel to the water surface. The diaphragm depth when it cracks is the cracking pressure in inches of WC.

Pete

Knowing just where the diaphragm happens to be below the water is the trick. It's shallower than the front of the purge cover, and the lever itself may move "up" a bit before flow starts as well, so while the method is fairly exact, it's much impossible to calibrate and won't give you much in terms of usable information.

You are better off with a magnahelic gauge or the under a dollar hardware store version above. Personally I'd use a smaller tube, but the difference is pretty minor.

 

[herman]

I add a few drops of food coloring to the water, makes it a lot easier to read.

 

[Rich Keller]

I think you are talking about how to check if your second stage is adjusted properly after service. I do not do this when I am servicing a reg but the simple answer is if you put the reg in the water mouth piece up it should free flow as soon as you put it in and then when you turn it over it should stop. That is how I know it is adjusted properly.

 

[spectrum]

I think you are talking about how to check if your second stage is adjusted properly after service. I do not do this when I am servicing a reg but the simple answer is if you put the reg in the water mouth piece up it should free flow as soon as you put it in and then when you turn it over it should stop. That is how I know it is adjusted properly.

As soon as you put it in? How soon?

 

[redacted]

As soon as you put it in? How soon?

Obviously regulator dependent but (with most Scubapros) I usually look for gas to be hissing before the water makes contact with the mouthpiece (sometime 1/4 to 1/2 inch before). If it gets up to or above the zip tie, I may take another shot at the adjustment (or it is just a dog). If water goes into the mouthpiece before it hisses, there is a problem.

While you are working out the spot, do some more tuning and dipping. After a while you will get to know what your reg is capable of. I rearely take the magnehelic out any more unless I just have to try to get a number. With my regs, I usually decide if it is right based on how it breathes and a dunk.