Can Gauges be Calabrated?

I have a pressure gauge that when compared to my AI computer gauge it is off by 120 psi. I looked the back of the gauge has a rubber plug but I do not see a method of adjustment under the plug. Based on picking up cooled fresh filled tanks it appears my digital AI computers pressure is closer to accurate then the analog gauge on my fill checker. I can always subtract 120 psi however if there is a method to calabrate the 2, I would prefer that.

Yes, it can. There are some good calibration houses in your area. It's been a long time since I've worked down there and I don't recall any off hand, but I do remember that there were a couple, back in 1997 . . . . I suggest contacting a local industrial supplier and asking them. The usually have sources for calibrating such instruments.

You may find that it is more fiscally prudent to buy a new gauge, but who knows ? ? ?