For helium gas measurement, Helium ( He) thermal mass flowmeter must do zero calibrated. The method is below：
1. To install the He flowmeter on the pipeline. When the pipeline is full of helium gas and does not flow, the gas at static condition ;
2. Press the ENT to enter the setting, enter the password 1000, press ENT to confirm, and press the upward arrow to cycle to the ”Zero voltage “ and “ current voltage”, , press ENT twice to make the “Zero Voltage” consistent with “ Current Voltage” , press ESC to exit
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