9
pH CALIBRATION
For better accuracy, frequent calibration of the instrument is recommended.
The instrument should be recalibrated for pH:
a) Whenever the pH electrode or temperature probe is replaced
b) At least once a week
c) After testing aggressive chemicals
d) When extreme accuracy is required
PREPARATION
Pour small quantities of pH 7.01 (HI7007) and pH 4.01 (HI7004) or pH 10.01
(HI7010) buffer solutions into two clean beakers.
For accurate calibration use two beakers for each buffer solution, one for rins-
ing the electrode tip, and one for calibration. In this way contamination of the
buffers is minimized.
For measurements in acidic samples, it is recommended to calibrate the meter
by using pH 7.01 (HI7007) and pH 4.01 (HI7004) buffers, while for alkaline
measurements use pH 7.01 (HI7007) and pH 10.01 (HI7010) buffers.
PROCEDURE
• Connect the pH electrode and the temperature probe, then switch the meter
ON.
• Remove the electrode protective cap, rinse the electrode
tip with pH 7.01 solution, then immerse the pH electrode
and temperature probe into pH 7.01 buffer solution;
stir gently and wait a few minutes for the electrode to
stabilize and reach thermal equilibrium.
Note: The electrode should be submerged approximately 4 cm
(1½”) into the solution. The temperature probe should
be located close to the pH electrode.
• Press RANGE to display pH measurement.
• Press CAL to enter the calibration mode. The buffer value @25 °C (77 °F)
and the “pH” symbol will blink on the display.
• The meter expects a pH 7.01 buffer.
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