Steps for measuring PH value of PH meter of acid meter
preparatory work/be about to work
1. The pH meter should be placed flat on the workbench in line with the use environment, and the bracket should be erected 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 lines, move the reference electrode and the clean pH electrode activated for more than 24 hours into the first standard buffer pH1 (for example, pH1=4.00), and adjust the positioning knob until the instrument shows "0.00" after the response of the instrument is stable; (2) Take the electric level system out of the first standard solution, rinse it with deionized water, then dry the water on the surface of the electric level with filter paper, and move it into the second standard solution (for example, pH2=9.18). After the instrument responds stably, adjust the slope knob to make the acidity meter display as (△pH=pH1- pH2=9.18-4.00=5.18), and then the slope knob will not. (3) After the slope adjustment is completed, readjust the positioning knob to make the instrument display the actual pH value (9.18) of the second standard solution, and the positioning is finished at 2 o'clock; (4) Take the electrode out of the second standard solution, wash it, blot it and move it into the solution to be tested. The displayed value after the instrument responds stably 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) Turn the slope compensation knob to the left; (3) Move the electric level system into the standard solution (only one standard solution is used in the one-point method, such as when the pH is 4.00), and adjust the positioning knob to make the instrument display "4.00"; (4) Take out the electric level, rinse and absorb water, and then move it into the solution to be tested. The displayed value after the instrument response is stable is the pH value of the solution to be tested.
Measurement of temperature
1. Turn the function selection to the temperature range.
2. Insert the temperature probe into the jack, and put the temperature probe into the environmental condition or solution. After the instrument response is stable, the instrument display value is the environmental condition or solution temperature value.
matters need attention
1. Carefully prepare the instrument before use.
2. When the display of the acidity meter is unstable or jumping around during power-on or measurement, the power supply should be cut off for inspection, such as whether the voltage, preheating time and electrode system are normal.
3. When using different electrodes, we should pay attention to eliminate the interference of ions, choose a good salt bridge, and use an ionic strength fixative when necessary.
4. Before the electrode system is taken out from the first solution and moved into the second solution, it must be cleaned with deionized water or double distilled water, and then the surface moisture is absorbed by filter paper to avoid affecting the accuracy of the determination results.
5. The instrument should be stored in a dry, clean and corrosion-free place. After each measurement, the power supply should be turned off, and the electrode and temperature probe should be properly kept. After cleaning, the glass electrode can be soaked in deionized water for later use (note that the water surface should not be lower than the glass bulb). After cleaning, the calomel electrode should be put on a rubber cap and stored in a matching box. When the calomel electrode is leaking or unsaturated and the salt bridge is interrupted, the saturated internal liquid should be replenished in time.
6. This kind of instrument adopts large-scale integrated circuits with high input resistance. When repairing and welding any parts inside the instrument, the soldering iron with good grounding wire below 45W should be used, and the soldering iron without grounding wire should be unplugged for welding.
