U-tube manometer

[Bubbletrubble]

While you can feel if a reg is tuned good very easily, a mag or manometer can clue in to over adjustment issues. If you tighten the orifice to much it can limit the amount of stroke on the poppet. This will limit the max flow rate, which at depth can be bad.

The way I tune my regs, over-tightening the orifice by such a wide margin that max flow rate would be dramatically affected is not a realistic possibility. I just don't see how I could f@#$ up the reg that bad during the tuning process. Maybe I'm just naive, I don't know.

 

[fppf]

Its actually not as hard to do as you may think.
Depending on the regulator design, the cracking effort is really a function of the spring and or balance system. Adjusting the orifice just preloads the system to it wont leak.

I have seen a fair share of regulators with lever arm slop, another way to detect over adjustments.

But for $10-$15 why not get one?

 

[Bubbletrubble]

Its actually not as hard to do as you may think.
Depending on the regulator design, the cracking effort is really a function of the spring and or balance system. Adjusting the orifice just preloads the system to it wont leak.

I understand how the balanced poppet system on my regs works. I'll admit, however, that I have very limited reg repair experience.

I have seen a fair share of regulators with lever arm slop, another way to detect over adjustments.

Lever arm slop = lever arm set too low affecting the seal between seat crown and rubber seating, right? If so, shaking the second stage up and down will cause some noisy rattling. Visual inspection should show where the lever arm is relative to the case rim. This problem will also be revealed by excessive travel of the purge button. A simple adjustment to the orifice will raise the lever arm to be approx. even with the case rim. This should get it to be pretty close to being properly tuned. If the lever arm looks bent, then it should be replaced. If the counterbalance cylinder, valve spring, or shuttle valve look wonky (compared to another properly functioning reg), I'd replace the malfunctioning part(s). At least that's how I'd deal with the issue on my regs and I wouldn't need a magnehelic

But for $10-$15 why not get one?

For quantifying cracking pressure to satisfy reg-geek curiosity, I could see its utility.
As a diagnostic tool for reg problems, I don't know how useful the info of an excessively high or low cracking pressure would be. Subjectively breathing off of the reg will already indicate that something's not right at which point troubleshooting would commence.

The other thing is that I don't like having to store unnecessary tools in my very small apartment. Moreover, I think it's pretty telling that the reg tech manual for my regs doesn't even mention the use of a manometer or magnehelic. Perhaps you guys are working on more complicated regs that require these extra tools, I don't know.

 

[fppf]

Does your reg manual quote a specific cracking pressure?
Some manufactures will have a general guide lines book for testing and cleaning.

 

[Bubbletrubble]

Does your reg manual quote a specific cracking pressure?

Nope. Believe me, I checked.

 

[fppf]

Nope. Believe me, I checked.

That surprises me? What regs?

 

[Bubbletrubble]

That surprises me? What regs?

Apeks. I was actually surprised, too. The older manual that I was using (2000 version) doesn't list any cracking pressure range.

Out of curiosity, I just downloaded a newer version (2006). In contrast, it does list a cracking pressure of +0.8 to +1.4 inches of water, but doesn't list a magnehelic or manometer as required equipment for servicing. The troubleshooting section simply states what to do if there's excessive work of breathing or freeflowing or water is entering the second stage. The manual doesn't describe how using accurate cracking pressure measurements can aid in diagnosis or repair of the reg in question (beyond subjective breathing tests or observation alone).

From experience, I can determine whether second stage cracking pressure is around 1 inch of water by subjective breathing alone. That's good enough for me for tuning purposes. If there's something dangerous that a purge test, observation, or subjective breathing test won't reveal, then please let me know. I will gladly start bidding on Dwyer magnehelic gauges on Ebay if that's the case.

 

[fppf]

Just a really good tool for a low price.
You can also use a dish of water which was used in the old days.

 

[Bubbletrubble]

Just a really good tool for a low price.
You can also use a dish of water which was used in the old days.

Yeah. After I finish second stage tuning, I'll fill a small bucket full of water and submerge the reg to check for any air leaks. At the same time, I'll lower the reg oriented diaphragm down into the water to do a quick-and-dirty cracking pressure check.

The magnehelic gauge sounds like a really nifty device, but I've come to the realization that I don't need one. Someday if I get completely bored and have some money burning a hole in my pocket, I'll splurge on one. I just don't see that day coming anytime soon.