Hetai PH InstrumentMainly composed of pH sensors（Glass electrodeComposed of calomel electrode, display, and support rod.pH sensormainlyGlass electrodeComposed of calomel electrodes, there are also composite electrodes that combine glass electrodes and calomel electrodes together. In order to eliminate errors caused by the temperature of the measured solution in glass electrodes,pH sensorIt is also equipped with temperature compensation electrodes to compensate for temperature errors. The function of a pH sensor is to use a glass electrode and a reference electrode to convert the pH of the measured solution into the corresponding potential, which is then sent to a display for displaying and recording the pH.
Calibration of pH measurement system
The pH measurement system (including measuring electrodes and displays) must be calibrated before measurement. For electrodes that are not used for a long time, soak the glass electrode in clean water or neutral test solution for 24 hours before calibration. During calibration and measurement, remove the sealing plug on the reference electrode replenishment hole, eliminate any bubbles that may exist in the reference solution, and maintain sufficient reference solution. There are two common calibration methods for pH measurement systems:
A little correction method. After the pH measurement system is fully installed, turn on the instrument power and then turn the slope knob of the instrument clockwise to the end (at this point, the instrument slope is 100%)pH electrodePut the prepared standard buffer solution with pH 7 or pH 4, adjust the temperature knob so that the indicated temperature is the same as the solution (if the pH monitor has an automatic temperature measurement system, this adjustment step can be avoided), and then adjust the positioning knob of the instrument so that the pH monitor displays the actual pH of the standard buffer solution. At this time, the instrument is ready for measurement after calibration. The knobs on the calibrated instrument must not be changed again.
Two point correction method. Translate into EnglishpH electrodePlace it in the prepared pH 7 standard buffer solution. After the display is stable, adjust the temperature knob so that the indicated temperature is the same as the solution (if the pH display has an automatic temperature measurement system, this adjustment step can be avoided), and then adjust the positioning knob of the instrument. Display the actual pH of the standard buffer solution on the pH monitor and remove itpH electrodeRinse with distilled water and dry with filter paper. Then place the pH electrode in the second standard buffer solution (usually one of the standard buffer solutions with pH 4 or pH 9). After the pH display is stable, adjust the slope knob of the pH display so that the pH measuring instrument displays the actual pH of the second standard buffer solution. After the slope correction, flush the pH electrode with distilled water and absorb water, and then put it back into the standard buffer solution with pH 7 for inspection. Repeat the adjustment to make these two steps meet the requirements. At this time, the PH measuring device is calibrated.