How to Troubleshoot PH Analyzer

In this article, you will find how you can troubleshoot problems with PH Analyzer with each problem and its solutions.

Introduction

Welcome again to this maintenance job series of articles. This article is a little different from other articles as this will tell us about the maintenance job on the analyzer.

Till now we have seen maintenance of different field instruments but here we will see pH analyzer maintenance jobs.

We will now see the maintenance jobs for the pH analyzer.

Problem> pH analyzer showing the constant value

Solutions:

1. The sample might be having an issue. Check the sample flow to the pH analyzer. The sample flow should be constant. Also, the flow should be laminar.
2. Check the isolation valves. No isolation valve should be isolated/throttled. Open it fully.
3. If the sample is not coming, then the tube will be choked. Dechoke the tube.
4. The force will be present in DCS/PLC, remove the force. The field pH transmitter might be in simulation mode. Remove it.
5. pH analyzer might be in the power-off condition. Check the power supply to the pH analyzer. Voltage should be as per the datasheet. Check the whole loop (connections, cable, fuse, barrier) if the voltage is not present.
6. If voltage is present but the analyzer is not in power condition, then either display is faulty or the power supply card is not working. Replace them one by one.
7. Lastly, try replacing the main PCB of the transmitter.
8. Analog input channels can also be in a faulty condition. Change the analog input channel if found faulty and do necessary configurations.

Problem> pH analyzer showing low/high value

Solutions:

1. A sample might be having an issue. Check the sample flow to the pH analyzer. The sample flow should be constant. Also, the flow should be laminar.
2. If the sample flow is low or high (flow can be seen in the rotameter. The flow will be mentioned in the datasheet), do proper setting using the needle valve in the line.
3. Check the isolation valves. No isolation valve should be isolated/throttled. Open it fully.
4. If the sample is not coming, then the tube will be choked. Dechoke the tube.
5. Check the sample tubing for leaks. If any leak is present in the sample tube, then attend to the leak.
6. Check the temperature from the settings. If the setting of the temperature is in manual mode, then keep it in auto mode. The temperature value should match with the process temperature. If it is not ok, then check/replace the element or pH probe if the temperature sensor is built.
7. Validate the pH analyzer using a standard solution. If the validation result is not proper, then do the calibration.
8. pH analyzer might be in the power-off condition. Check the power supply to the pH analyzer. Voltage should be as per the datasheet. Check the whole loop if the voltage is not present.
9. If voltage is present but the analyzer is not in power on condition, then either display is faulty or the power supply card is not working. Replace them one by one.
10. Lastly, try replacing the main PCB of the transmitter.
11. Analog input channels can also be in flawed condition. Change the analog input channel if found faulty and do necessary configurations.

Problem> pH analyzer value fluctuating

Solutions:

1. The sample to the analyzer should be constant and laminar. The flow can be seen in the rotameter. Set the flow as per the flow mentioned in the datasheet.
2. Check the isolation valves. No isolation valve should be isolated/throttled. Open it fully.
3. Check the sample tubing for leak. If any leak is present in the sample tube, then attend the leak.
4. Put the pH sensor in the solution of known pH. If the value is still fluctuating, then check all the connections of the pH sensor and the transmitter, connections will be loose.
5. Check the pH sensor’s tip. It should not be damaged.
6. Check the earthing cable.

Problem> pH analyzer value mismatch with lab results

Solutions:

1. Check the sample flow to the pH analyzer. The sample flow should be constant. Also, the flow should be laminar.
2. Check the isolation valves. No isolation valve should be isolated/throttled. Open it fully.
3. If the sample is not coming, then the tube might be choked. Dechoke the tube.
4. Check the temperature from the settings. If the setting of the temperature is in manual mode, then keep it in auto mode. The temperature value should match with the process temperature. If it is not ok, then replace the element or pH probe if the temperature sensor is inbuilt.
5. Validate the pH analyzer using a standard solution. If the validation result is not proper, then do the calibration.
6. Check the pH sensor’s tip. It should not be damaged.

EndNote

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