Magnehelic Gauge - How Should it Behave

[aalbert]

Bought one magnehelic gauge, that came with the bracket pictured. hoses, case, etc... but it wouldn't budge whether sucking or blowing (guess it is just getting old ). Oh well, figured I got $20 in accessories in the equation.

Bought another one on eBay for about the same monies.. This one moves, etc, but isn't smooth at all when I inhale ... it bounces around between .6 and .9, and not with any consistency.. In general how should the needle behave? Do I need to get #3?

 

[northernone]

Bought one magnehelic gauge, that came with the bracket pictured. hoses, case, etc... but it wouldn't budge whether sucking or blowing (guess it is just getting old ). Oh well, figured I got $20 in accessories in the equation.

Bought another one on eBay for about the same monies.. This one moves, etc, but isn't smooth at all when I inhale ... it bounces around between .6 and .9, and not with any consistency.. In general how should the needle behave? Do I need to get #3?

View attachment 483991

Mine the needle moves smoothly and I can hold a level without trouble. Small fluctuations only. There are some good videos on YouTube that would show how it should behave. (Poor connection here, won't load, sorry.)

Consider making one with clear tubing and a measuring stick?

 

[Pao]

It is really a little "bouncy" especially when trying to suck/blow by mouth. What you could do is to hook it up with an actual water manometer (quite easy to build one) and see how it reads.

 

[rsingler]

As for the one that doesn't move, make sure that ONE of the plugs on the back are removed to allow air flow.

As for the bouncy air flow, that's very typical. It shows just how sensitive the magnehelic really is. You need careful breath control to use it and test the cracking effort of your second stage. We're talking 0.05 psi.

You're on the right track!

Also note that when you adjust the zero, it's for a horizontal or vertical position as you check, but not both.

 

[Pao]

As for the one that doesn't move, make sure that ONE of the plugs on the back are removed to allow air flow.

You should still see a tiny bit of movement even if the other port is closed. My ports are on the side. I think it depends on the model. You can download the manual for your particular model on their website.

 

[JamesBon92007]

Anyone reading this thread would probably be interested in this too (from herman):

DIY regulator test/flow panel

 

[aalbert]

Guess I will download the manual and give it a read. Both units were setup for side mounting of the hoses, though I had to rob the barbs from the first one to provision the 2nd one.. Will work on my breathing a bit, and post some video at some point. Definitely not as smooth as what I saw on a youtube video, but that was also with a machine doing the "breathing".