Hanna Instruments HI 221 - Manual (Page 11)

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CAL
pH
C
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• Press the ARROW keys to select a different buffer value, if necessary.
• When the reading is stable and close to the selected buffer, the “CFM”
tag will blink and if enabled, an audible signal will sound.
• Press the CFM key to confirm the calibration. The instrument will ask for a
second calibration buffer and display the measured pH on the first LCD line
and the second calibration buffer on the second LCD line.
• If necessary, press the ARROW keys to select a different buffer value.
Note: The instrument will automatically skip the buffer used for the first point.
It also skips 6.86 if 7.01 was used, and vice versa. Likewise, it will skip
9.18 if 10.01 has been used, and vice versa.
• Rinse the electrode in one of the beakers of the second buffer solution, then
immerse the pH electrode and the temperature probe approximately 4 cm
(1½”) into the second buffer solution and stir gently. The temperature
probe should be close to the pH electrode.
• The “ ” indication will blink on LCD until the reading has stabilized.
• When the reading is stable and close to the selected buffer, the
“CFM” tag will blink.
• Press the CFM key to confirm the calibration.
The instrument will return to normal operation and will memorize the calibra-
tion data.
Note: Press the RANGE key any time during calibration to display the
temperature reading.
ONE-POINT CALIBRATION
• Proceed as described in “two-point calibration”.
• Press the CAL key after the first calibration point has been confirmed.
The instrument will return to normal operation and will memorize the one-
point calibration data.
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