Hanna Instruments HI 3220 - Manual (Page 15)

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pppppH CALIBRATION H CALIBRATION H CALIBRATION H CALIBRATION H CALIBRATION
It is recommended to calibrate the instrument frequently, especially if high
accuracy is required.
The pH range should be recalibrated:
• Whenever the pH electrode is replaced.
• At least once a week.
• After testing aggressive chemicals.
• When calibration alarm time out is expired - “CAL DUE” blinks (if feature
is enabled in SETUP).
• If “Outside Cal Range” message blinks during pH measurement (the
measurement range is not covered by current calibration, if this feature is
enabled in SETUP).
PROCEDURE
The HI 32xx family offers a choice of 7 standard buffers (1.68, 4.01, 6.86,
7.01, 9.18, 10.01 and 12.45 pH) and up to 5 custom buffers. The standard
pH buffers are temperature compensated during calibration. The custom, user
entered buffers are not temperature compensated during calibration.
When a custom buffer is selected during calibration, the “Custom” function
key is displayed on the LCD. Press Custom key in order to alter the value to the
actual pH value at the temperature of measurement. Use ARROW keys to
change the value within a ±1.00 pH window and then press Accept. Press
ESC to leave custom buffers value unchanged. Press Confirm.
For accurate pH measurements, it is recommended to perform a multipoint
calibration. At least a two-point calibration is required.
The instrument will automatically skip the buffers within ±0.2 pH window,
around one of the calibrated buffers.
• Pour small quantities of selected buffer solutions into clean beakers. For
accurate calibration use two beakers for each buffer solution, the first one for
rinsing the electrode and the second one for calibration.
• Remove the protective cap, open the fill hole and rinse the electrode with
some of the buffer solution to be used for the first calibration point.
FIVE-POINT CALIBRATION FIVE-POINT CALIBRATION FIVE-POINT CALIBRATION FIVE-POINT CALIBRATION FIVE-POINT CALIBRATION
• Immerse the pH electrode and the temperature
probe approximately 3 cm (1¼”) into a buffer solu-
tion of your choice (pH 1.68, 4.01, 6.86, 7.01,
9.18, 10.01, 12.45 or a custom buffer) and stir
the buffer gently. The temperature probe should be
close to the pH electrode.
3 cm