1. First, check whether the barometer is intact. Prepare a manual pressure pump and a standard digital pressure gauge as a reference for calibration.

2. Check whether the barometer is zeroed. If it is not zeroed, adjust it to zero and then connect it to the manual pressure pump.

3. After the connection is completed, close the exhaust valve on the pressure pump, and then slowly increase the pressure. After the pressure is increased, record the indicated value.

4. Generally, the barometer only needs to be tested 3-4 times. The test values are 20, 40, 60 and 80 bar pressure respectively. Then record the indicated value and compare it after the test.