How To Calibrate a Pressure Switch

How To Calibrate a Pressure Switch/Procedure for pressure switch calibration.

Pressure Source
Accurate Gauge
Microswitch contact monitoring device.
For high-pressure applications, a Hand pump is more suitable.
For low-pressure shop air or simple regulated pressure can be used or electronic pressure source can be used.
Pressure should have an accuracy of 0.25 %

Procedure for the Pressure Switch Bench Calibration.

Connect the pressure switch to a hand pressure regulator and test gauge, as shown in the diagram above.

With a Multimeter, set to the continuity range to check and verify that the switch contacts are as indicated: NO (Normally open) and NC (Normally close).
Connect the Ohmmeter or DMM between the normally open contacts (NO) and the common terminal (C) of the switch. The meter should read ―open circuit. Adjust the hand pressure regulator to increase the pressure to the set point of the pressure switch until the contacts change over. The meter should now read ―short circuit. Note the pressure reading and write it down. This pressure is the switch setpoint for a ―rising pressure
Increase the pressure to the switch to its maximum rating. Slowly reduce the pressure to the switch until the switch changes over from closed to normally open again. Note and write down this pressure reading. This pressure is the switch setting for a ―falling pressure.
When error found, adjust setpoint by screw adjustment and repeat until the desired value obtained
From the readings, you have taken work out the pressure difference between the rising and falling pressure settings. This is called the ―dead band‖ of the switch. The dead-band calculated should be equal to or less than the manufacturers ‘dead-band. The maximum dead band is usually stated by the manufacturer.