Introduction to pH measurement steps of acidity meter
Preparation work
1. The acidity meter should be placed flat on a workbench that is suitable for the usage environment, and the bracket should be supported according to the visual angle.
2. Positioning measurement method of pH value: (1) Two point positioning method (high-precision measurement method) (1) Connect the electrode circuit, move the reference electrode and the PH electrode that has been activated for more than 24 hours into the first standard buffer pH1 (e.g. pH1=4.00), and adjust the positioning knob until the instrument displays "0.00" after the instrument response is stable; (2) Take the electric level system out of the first standard solution, wash it with deionized water, dry the surface of the electric level with filter paper, and transfer it into the second standard solution (e.g. pH2=9.18). After the instrument response is stable, adjust the slope knob so that the acidity meter displays (△ pH=pH1- pH2=9.18-4.00=5.18). The slope knob can not be moved again after that, unless the electrode system is replaced; (3) After the slope adjustment is completed, readjust the positioning knob so that the instrument displays the actual pH value (9.18) of the second standard solution, and the positioning at this two points is completed; (4) Remove the electrode from the second standard solution, rinse it, dry it, and then transfer it into the solution to be tested. After the instrument responds stably, the displayed value is the pH value of the solution to be tested. （2） One point positioning method (rough measurement method) (1) Adjust the temperature compensation knob to the solution temperature value; (2) Rotate the slope compensation knob to the left to the head; (3) Move the electrical level system into a standard solution (using only one standard solution for the one point method, such as pH=4.00), and adjust the positioning knob to display "4.00" on the instrument; (4) After removing the electric level rinse and absorbing water, transfer it to the solution to be tested. After the instrument responds stably, the displayed value is the pH value of the solution to be tested.
Temperature measurement
1. Turn the function selection to the temperature range.
2. Insert the temperature probe into the socket and place it in the environmental conditions or solution. After the instrument responds stably, the displayed value of the instrument will be the environmental conditions or solution temperature value.
matters needing attention
1. Carefully prepare the instrument before use.
After the acidity meter is powered on or during the measurement process, if there is an unstable or jumping display, the power should be cut off for inspection, such as whether the voltage, preheating time, and electrode system are normal.
3. When using different electrodes, attention should be paid to eliminating ion interference, selecting a good salt bridge, and using ion strength fixatives if necessary.
4. Before removing the electrode system from the first solution and transferring it to the second solution, it must be cleaned with deionized water or double distilled water, and then filter paper should be used to absorb surface moisture to avoid affecting the accuracy of the measurement results.
5. The instrument should be stored in a dry, clean, and corrosion-free place. After each measurement, the power should be turned off, and the electrode and temperature probe should be properly stored. After cleaning the glass electrode, it can be immersed in deionized water for use (note that the water surface should not be lower than the glass bulb). After cleaning the calomel electrode, cover it with a rubber cap and store it in a matching box. When the filling liquid inside the calomel electrode leaks or is not saturated or the salt bridge is interrupted, the saturated filling liquid should be replenished in a timely manner.
6. These instruments all use large-scale integrated circuits with high input resistance values. When repairing or welding any internal components of the instrument, 45 should be used
