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(3) Thoroughly wash the glass electrode with water (distilled, pure or tap water).
(4) Absorb the water on the glass electrode, and then press the CAL key to enter the calibration mode.
Check that [4.00] is displayed on the LCD and "CA: Voltage" appears on the display.
Note: "Err" is displayed on the voltage section of the LCD, if the sensor probe is not
connected to the unit or the glass electrode is dry. To reset the display to the
voltage, place the glass electrode in the pH standard solution. If the reset fails,
the sensor probe or the standard solution may be faulty. Refer to the
troubleshooting section.
(5) Immerse the glass electrode into the pH 4 standard solution. Slowly stir the solution with the
electrode, and then hold the sensor probe still until the voltage reading becomes stable.
(6) When the voltage reading becomes stable, set the calibration value to "4.01" by
pressing the pH/mV or
key.
The pH value of the standard solution at 25°C is "4.01".
For the relation between the pH value of standard solution and the temperature, refer
to the section "Relation between the pH value and temperature" on page 20.
For example, when the pH standard solution is 40°C, the pH calibration value is "4.04".
(7) Press the REC key to store the calibration value in the unit memory.
“SA” is displayed on the LCD to indicate that the calibration data has been
stored in
the unit memory.
Now the pH 4 calibration is complete.
(8) The unit automatically proceeds to the pH 7 calibration. Wash the glass electrode
with water (distilled, pure or tap water).
(9) After washing, use clean filter paper, cotton swabs or tissue paper to absorb the water on the
glass electrode. When wiping the glass electrode to absorb water, be careful not to rub the glass
electrode. Otherwise static electricity will build up and the pH readings will become unstable.
(10) Perform calibration on pH 7 and pH 10 by using the same procedure as for pH 4.
The figure above shows the case The figure above shows the case
when the pH 7 standard solution is 26.3°C. when the pH 10 standard solution is
26.3°C
Every data for each pH calibration must be stored in the unit memory by pressing the REC key.
(11) After approx. 3 seconds, the unit returns to the measurement mode.
When the pH 10 calibration is complete, "End" is displayed on the LCD.
An accurate pH measurement is possible with the procedures described above.
Note: While in the calibration mode, "CA" and the voltage are displayed on the LCD. When an
acid
solution is measured, the voltage value is positive. When an alkaline solution is measured,