1) Close the positive and negative pressure primary valves;

2) Slowly open the positive and negative pressure vent valves to discharge (pay attention to connecting them with a drain bucket)

3) Check and adjust the zero position of the instrument;

4) Use and clean the site.

2、 Range calibration steps for dual flange level transmitters:

Preparation: Standard pressure signal generator, standard ammeter, 24VDC power supply and connectors, wires, etc.

1) Open the positive and negative pressure chambers of the instrument to the atmosphere, connect the power supply and stabilize for 3 minutes, then set the damping time to the minimum. At this time, the transmitter is 4mA. Otherwise, adjust the zero point screw to output 4mA;

2) Input range signal to the positive pressure chamber of the double flange liquid level transmitter, negative pressure is vented to the atmosphere, and the transmitter output is 20 mA. If there is a deviation, adjust the range screw to output 20 mA. If the zero position screw does not meet the requirements, cut off the power, change the position of the migration plug, and then connect the power supply before performing zero position migration;

3) Repeat steps 1 and 2 until they meet the requirements;

4) When the double flange liquid level transmitter needs to perform zero point migration, the corresponding pressure side of the instrument should be applied with the initial differential pressure for measurement, and the zero point screw should be adjusted to output 4mA;

5) Divide the measurement range into 5 points, and input signals at 0%, 25%, 50%, 75% point by point. The output value of the transmitter should be within the allowable range. If it exceeds the tolerance, adjust the zero position and range repeatedly;

6) Use instruments and inform the process;

7) Fill in the verification form