In this article, we will discuss troubleshooting DP type Transmitter Common Problems. DP-type pressure is one of the most widely used pressure transmitters. We use a DP transmitter for the measurement of differential pressure, flow, and level, We encounter many problems with DP-type pressure transmitters in our daily routine activities.
DP Transmitter Common Problems
Some common problems in DP-type transmitter are :
Let us see the troubleshooting guidelines for the problems mentioned in DP type transmitter
Follow the below-mentioned steps:
1. DP-type pressure transmitter in power-off condition :
Check the cable connection in the DP-type pressure transmitter. All connections should be tight. Then check the voltage. If no voltage is found, then check the connections in the junction box and marshaling cabinet. Do proper cable tightening if the cable is loose. Check the fuse in the marshaling cabinet. If the fuse is blown, replace the fuse. Also, we can check the cable healthiness if everything is found ok.
2. Value mismatch in field and PLC/DCS
If the value in the DP-type pressure transmitter is not matching with the value in the PLC/DCS, then check the range in the field and system side. The datasheet contains the range of the DP-type pressure transmitter. Check both ranges. Make them the same if the ranges are different.
3. DP transmitter not showing the proper value
- Check the process isolation valves of the DP-type pressure transmitter. Both the HP and LP side isolation valve should be open.
- Check the manifold. The equalization valve should be in close condition. The isolation valves in the manifold should be in open condition. The vent ports should be in close condition.
- Check all the tubing conditions. No leakage should be there from the fittings. No tube should be punctured. Attend the tube leakage or replace the punctured tube after properly isolating the DP-type pressure transmitter.
- The tubes can be choked. Flushing or closed drain flushing is required to do dechoking of the tube. If flushing does not work, then use the pump to dechoke the tube. Do not over-pressurize the dechoking fluid. Apply only pressure of a maximum of 1.5 times that of the DP-type pressure transmitter’s upper range.
- Check the connection of the HP tube on the HP side of the DP-type pressure transmitter and the LP tube on the LP side of the pressure transmitter. Correct the tubing if found swapped.
- Check whether any force is present in the field or in the PLC/DCS. If force is present, remove force after informing all higher authorities in the process as well as in the Instrumentation department, or remove force after filling up the interlock restoration form.
- Check the calibration of the DP-type pressure transmitter. If during calibration, the DP type pressure transmitter fails, then do calibration of the DP type pressure transmitter or replace the DP type pressure transmitter.
- Check all configurations like lower range value, upper range value, mA range, and device address if any as per the datasheet of the DP-type pressure transmitter.
4. DP type pressure transmitter value fluctuating
- Check the tube leakages. Tube leakage can cause fluctuation in the reading of the DP-type pressure transmitter.
- Increase the damping factor in the DP-type pressure transmitter if the fluctuations are very high