How to determine whether a differential pressure transmitter is operating properly in the field?

Close the high and low pressure tapping valves of the Guan San valve assembly, open the balance valve to check whether it returns to zero; this helps determine if there is any zero drift. Then close the balance valve and open the plug in one of the measurement chambers, expose it to atmospheric pressure, and slowly open the tapping valve on the other side to observe whether the value displayed by the transmitter changes in a consistent manner

If the display value of the differential pressure transmitter, or the corresponding flow and level values, are essentially consistent with the values required by the process, it can be determined that the differential pressure transmitter is operating properly in the field.

Since the common faults of differential pressure transmitters are zero drift and clogging of the pressure guiding tube, it is rare to calibrate the scale point by point on-site; instead, the zero point and the trend of changes are checked. The specific methods are as follows: 1) Zero point check: Close the positive pressure valve, open the balance valve, and close the negative pressure valve. At this time, the output current of the transmitter should be 4mA. 2) Trend inspection: After the zero-point check, each valve returns to its original open position, with the drain valve of the negative pressure chamber being slightly opened. At this point, the transmitter’s output should increase ； If the positive pressure chamber drain valve is opened, the output decreases. Through the above checks, it can be preliminarily determined that the transmitter is operating normally.