How to disassemble, repair and calibrate an air pressure gauge

How does an air pressure gauge work?

How to take apart an air pressure gauge?

Is your pressure gauge miscalibrated? How to re-calibrate?

I try to answer these questions in this short video.

-if the bezel is pressure fit, simply pry it off little by little.
-take out the two screws from the back of the gauge
-remove the mechanism from the case
-bend the calibrating piece with pliers gently until you get the needle to point to 0 at rest, but not rest with any force on the stop if there is one.
-compare to a known good gauge and readjust until satisfied.

NOTE: your gauge might not have a calibration element. After I took this video, I took apart my second gauge, and I realized that that one does not have that calibration link, but a straight link instead. So what I did with that one is I bent the big semicircular element - the Bourdon tube - inwards, right near the block it's attached to. It's key that you bend right near the block, otherwise the dial will keep moving further and further from 0. You need to do this gently, but you can generally bend it back the other way if you've gone too far. You keep gently bending it in either direction until you get the calibration where you want it.

You can get more information than you ever wanted to know about these Bourdon gauges on Wikipedia: https://en.wikipedia.org/wiki/Pressure_measurement#Bourdon

See my related video on how an air compressor works: https://www.youtube.com/watch?v=GbGBK6MIyIs

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