Pressure gauge calibration is one of the simplest calibration procedures.Pressure gauges are pressure indicating instruments. Normally pressure gauges consist of bourdon tubes as pressure sensing elements.
There are different types of pressure gauges based on different manufactures so the calibration methods will also change let’s see some calibration methods.
Adjusting the knob at the lower side of the pressure gauge.
Some pressure gauges have knob for calibration outside the gauges like shown in fig above.
Just remove the lock and calibrate the gauge.
Adjusting the screw located inside the pressure gauge mechanism.
In some gauges manufactures provide the calibration screw in the dial pad (as you can see in the below fig. Near to the pointer) adjust that screw to calibrate.
Adjusting the screw located at the gauge needle pointer itself.
Some gauge manufactures provide calibrating screw in the pointer. Adjust the screw to calibrate.
Opening the Pressure Gauge Protective Glass (or plastic cover) then removing the needle.
Open the protective glass of pressure gauge to calibrate and adjust zero and span. Opening the glass by Craftsman 2 pc 16” Rubber Strap Wrench Set using needle puller pull the needle and adjust o psi and span by applying pressure by hand held test pump or by any other means.
Basic procedure of pressure gauge calibration.
- Connect the equipment’s as shown in above figure to calibrate the pressure gauge.
- Apply pressure 0%(zero adjust)
- Adjust the zero screw or put the pointer on 0%
- Apply pressure 100%(span adjustment)
- To correct the indication increase or decrease the sector arm
- Apply pressure 50%(linear adjust)
- Adjust the length of link or pull the pointer using puller and place at correct spot
- Check points 0%,25%,50%,70% and 100%
- Repeat these steps to get correct values