pH analyzer is the most used process analyzer used mainly in knowing the quality of the water. Accurate measurement of pH is very important to maintain the quality of the water. If the pH of the water is not maintained, then the water will degrade the quality of all the equipment using this water.
This article describes some common pH analyzer problems and their troubleshooting.
Common Problems of pH Analyzer
Some common problems of pH analyzer transmitters are :
Let us see the troubleshooting guidelines for the problems mentioned in the pH analyzer
Follow the below-mentioned steps to troubleshoot the ph Analyzer problems.
1. pH analyzer in the power-off condition
Check the cable connection in the pH analyzer in the field. All connections should be tight and properly lugged. Then check the supply voltage. If voltage is not found, then check the connections in the junction box and the marshalling cabinet. Do proper cable tightening if the cable is loose, and proper lugging if the cable is not properly lugged. Check the fuse in the marshalling cabinet also. If the fuse is blown, then replace the fuse. Check the barrier in the marshalling cabinet. If the barrier has faults, then replace the barrier. Also, we can check the cable healthiness if everything mentioned above is found ok.
2. pH Value mismatch in field and PLC/DCS
If the value in the pH analyzer is not matching with the value in the PLC/DCS, then check the range in the field analyzer and on the system side. The range of pH is 0 to 14. Change the range in the field or the PLCDCS whichever is not proper.
3. pH value not matching with the laboratory results
The followings may be the causes.
- pH value not matching with the laboratory results
- Check the sample with the pH analyzer. If no sample is found, then check the isolation valve of the sampling system. If the isolation valve is closed, then open the isolation valve. The tube can also be choked. Dechoke the tubing.
- Check sample flow rate. Establish proper flow rate as per the flow rate mentioned in the datasheet of the pH analyzer.
- The sample to the pH analyzer should be without air bubbles. If any air bubble is present, then give proper tubing to vent the air bubble from the sampling system.
- Remove the pH sensor and check the physical condition of the pH sensor. If the pH sensor is in damaged condition, then replace the pH sensor.
- The tubes can be having leakages. Attend the leakages to get proper pH value.
- Check the internal RTD of the pH sensor. If the temperature measurement is in manual mode, then put the temperature measurement in auto mode.
- Check whether any force is present in the field or in the PLC/DCS. If force is present, then remove force after informing all higher authorities in the process as well as in the Instrumentation department. Alternatively, if the bypass procedure is followed, then remove the force after filling up the interlock restoration form.
- Check the calibration of the pH analyzer. If during calibration, the pH analyzer is having calibration issues, then do calibration of the pH analyzer transmitter or replace the pH sensor or the pH transmitter.
- Check all configurations like the range of the pH, mA range, and device address if any as per the datasheet of the pH analyzer.
4. PH analyzer value fluctuating
- Check the sample tube leakages. Tube leakage can cause fluctuation in the reading of the pH analyzer.
- Increase the damping factor in the pH analyzer if the fluctuations are very
