Check that all screws are tightened and that the pointer axis and pointer touch the glass during verification. Then shake the pressure gauge gently and listen to the noise, so as not to leave parts or debris in. The scale dial and the lens of the pressure gauge should be bright and clear, which can correctly display the indicated pressure value. When the pointer position of the case is unchanged by tapping, then install the pressure gauge on the calibrator. When working medium is liquid, should check that the height of the pointer axis of the standard meter is equal to that of the two meters to avoid the indication error caused by the different liquid level.