How to Check the Accuracy of Your pH Meter
A pH meter, also known as an acidity meter, is a commonly used instrument for measuring the pH value of a liquid solution. Like many other instruments in the laboratory, the pH meter should be "calibrated" regularly before use, so as to ensure the accuracy of the measurement data.
To judge whether the pH meter test is accurate or not, the most reliable method is to use pH standard buffer solution for verification. The verification method is as follows:
Take standard buffer solutions with three pH values: pH 6.86 solution, pH 4.00 solution, and pH 9.18 solution. It is necessary to ensure that the temperature of the three solutions is the same, preferably a freshly prepared solution, so as to avoid the deterioration of the solution due to the influence of the environment during long-term storage. The pH 6.86 solution was then used for positioning calibration and the pH 4.00 solution for slope calibration. Finally, use a pH meter to test the solution with a pH value of 9.18. If the measured value is 9.18, it means that the pH meter is accurate.
If the measurement is inaccurate, the pH meter may be malfunctioning. Sooke Purchasing Manager has sorted out the following common faults and solutions of the pH meter for your reference:
1. Inaccurate measurement data
Possible reasons: There are many reasons for inaccurate measurement data, the biggest possibility is that the detection method is not in compliance, or the temperature and slope adjustment points are wrong
Solution: Calibrate the instrument several times. Strictly follow the instructions and operating procedures to minimize the measurement errors caused by labor, temperature, solution impurities and other reasons during the measurement process. If the problem still occurs, it may be that the instrument itself is faulty, and you can contact the manufacturer for after-sales service.
2. The pH meter shows unstable numbers
possible reason:
(1) The connection of the instrument parts is not stable Solution: re-insert the instrument tightly
(2) The power supply voltage is unstable Solution: Use a regulated power supply
(3) The circuit board is corroded due to long-term use in a polluted environment. Solution: replace the circuit board
(4) The operational amplifier in the circuit board is burned out Solution: replace the operational amplifier
3. When using two standard solutions for testing, they cannot be positioned with each other
Possible cause: The signal generator is inaccurate
Solution: repair or replace the signal generator
4. Failure of temperature, slope or calibration adjustments
Possible cause: The potentiometer connected to the adjustment knob is damaged
Solution: repair potentiometer
5. The indicator light does not light up after the power is turned on
Possible reasons: (1) The indicator light is burnt out (2) The fuse is blown (3) The transformer is burned out
