How to troubleshoot DP type Level Transmitter

In this article, you will find how you can troubleshoot DP type Level Transmitter with each problem and its solutions.

Introduction

Here we come with a new article on the maintenance of DP-type level transmitters.

DP type level transmitters are used in various configurations like open tanks and closed tanks with either dry-leg or wet-leg type configurations. In this article, we will see the maintenance jobs on all such DP type level transmitters.

Problem> DP type level transmitter showing Zero

Solutions:

1. Check the isolation valves installed for isolation of the process fluid tubes. All isolation valves to the manifold should be open.
2. Also, in the manifold, isolation valves should be open and the equalization valve should be closed.
3. Check whether the vent port is properly fixed or not.
4. The tube might be choked fully. Follow the procedure to dechoke the tube.
5. Ensure that the HP side of the transmitter is connected to the tank’s bottom and the LP side is connected to the top of the tank or open to the atmosphere as per drawings.
6. If the DP type level transmitter is wet leg type, then check whether the legs are properly filled or not. Fill them properly by using proper fill fluid.
7. Check the DCS/PLC/ESD for force. Even the DP type level transmitter could be in simulation mode. Remove it.
8. The DP type level transmitter can be in power-off condition. Check the voltage. If voltage is not available then check the loop which includes cable terminations, fuse, barrier, and cable condition.
9. DP type level transmitter might be in a faulty state. Replace the transmitter and do the necessary configurations as per the datasheet.
10. Analog input channel might be in a faulty condition which is an infrequent case. Change the AI channel and do the necessary configurations.

Problem> DP type level transmitter showing low-value

Solutions:

1. Check the isolation valves installed for isolation of the process fluid tubes. All isolation valves to the manifold should be open. None of them should be in throttled condition.
2. Also, in the manifold, isolation valves should be open and the equalization valve should be closed. All of the isolation valves should be properly opened and none should be throttled. 
3. The tube might be in a choking condition. Follow the procedure to dechoke the tube.
4. Attend leakage in the tube if any leakage is present.
5. Ensure that the HP side of the transmitter is connected to the tank’s bottom and the LP side is connected to the top of the tank or open to the atmosphere as per drawings.
6. If the DP type level transmitter is wet leg type, then check whether the legs are properly filled or not. Fill them properly by using proper fill fluid.
7. Check the transmitter’s response by giving pressure through a properly calibrated instrument. Do calibration if needed.
8. The Analog input channel might be in a faulty condition which is a rare case. Change the AI channel and do the necessary configurations.

Problem> DP type level transmitter showing high value

Solutions:

1. Check the isolation valves installed for isolation of the process fluid tubes. All isolation valves to the manifold should be open.
2. Also, in the manifold, isolation valves should be open and the equalization valve should be closed.
3. Check whether the vent port is properly fixed or not.
4. If the DP type level transmitter is wet leg type, then check whether the legs are properly filled or not. Fill them properly by using proper fill fluid.
5. Check the transmitter’s response by giving pressure through a properly calibrated instrument. Do calibration if needed.
6. The Analog input channel might be in a faulty condition which is a rare case. Change the AI channel and do the necessary configurations.

Problem> DP type level transmitter value not stable

Solutions:

1. Check the isolation valves installed for isolation of the process fluid tubes. All isolation valves to the manifold should be open. None of them should be in throttled condition.
2. Also, in the manifold, isolation valves should be open and the equalization valve should be closed. All of the isolation valves should be properly opened and none should be throttled. 
3. Check whether the vent port is properly fixed or not.
4. The tube might be choked or partially choked. Dechoke it and flush it properly.
5. Attend tube leakage if leakage is found.
6. If the DP type level transmitter is wet leg type, then check whether the legs are properly filled or not. Fill them properly by using proper fill fluid.
7. The Analog input channel might be in a faulty condition which is a rare case. Change the AI channel and do the necessary configurations.

Problem> DP type level transmitter showing the constant value

Solutions:

1. Check the isolation valves installed for isolation of the process fluid tubes. All isolation valves to the manifold should be open. None of them should be in throttled condition.
2. Also, in the manifold, isolation valves should be open and the equalization valve should be closed. All of the isolation valves should be properly opened and none should be throttled. 
3. Check whether the vent port is properly fixed or not.
4. The tube might be choked or partially choked. Dechoke it and flush it properly.
5. Check the transmitter’s response by giving pressure through a properly calibrated instrument. Do calibration if needed.
6. Check the DCS/PLC/ESD for force. Even the DP type level transmitter could be in simulation mode. Remove it.
7. The Analog input channel might be in a faulty condition which is a rare case. Change the AI channel and do the necessary configurations.

Problem> DP type level transmitter incorrect in field and on DCS/PLC/SCADA

Solutions:

1. Range mismatch in field display and the graphics can lead this issue. Configure the range as per the datasheet on both sides.

Problem> DP type level transmitter displays off

Solutions:

1. Failed display is one reason. Change the display.
2. The DP type level transmitter can be in power-off condition. Check the voltage. If voltage is not available then check the loop which includes cable terminations, fuse, barrier, and cable condition.
3. DP type level transmitter might have become faulty. Replace the transmitter and do the necessary configurations.

EndNote

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