Introduction to Calibration Method of PH Meter

The calibration period of the pH meter is generally 3 months. The calibration method and steps are as follows. (1) Preparations before calibration ① Prepare two beakers, distilled water, standard buffer solutions with low pH and high pH, ​​and a mercury thermometer at 0-100°C. ②Pour enough low pH standard buffer solution into one beaker, and pour enough high pH standard buffer solution into another beaker. ③ Take out the electrode system from the electrode chamber. (2) Zero point calibration ① Clean the electrode (PH electrode) system with distilled water, dry it with filter paper, and immerse it in the standard buffer solution with a pH value of 6.86. ② Measure the solution temperature when the electrode system is balanced with the solution temperature and the transmitter (or converter) indicates stable, and find out the pH value of the solution at this temperature according to the 'standard buffer solution pH value-temperature comparison table'. ③Adjust the zero adjustment (or asymmetry) potentiometer of the meter so that the meter indicates the above pH value. (3) Range (or slope) calibration (one-point calibration) Take the electrode (PH electrode) system out of the beaker, wash it with distilled water, dry it with filter paper, and immerse it in the standard buffer solution with a pH value of 4.01 or 9.18. The choice of these two buffer solutions is based on the principle that the pH value of the measured solution is close to the pH value of the standard buffer solution used for calibration. (4) Range (or slope) calibration ① Take the electrode system out of the beaker, wash it with distilled water, dry it with filter paper, and immerse it in a standard buffer solution with a high pH value (PH4 or PH9). ②Measure the solution temperature when the electrode system is in balance with the solution temperature and the transmitter (or converter) indicates stable}, and find out the pH value of the solution at this temperature according to the 'comparison table'. ③Adjust the range (or slope) potentiometer of the meter to make the meter (PH meter) above the pH value. (5) Repeat the calibration Repeat the above zero point and span calibration steps until the indicator is accurate.