Hanna Instruments HI 120 - Manual (Page 16)

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All new calibrations will override existing stored calibration data, in a ±0.2
pH window, at these calibration points. The slopes adjacent to the calibration
points will be reevaluated.
If the new calibration point has no correspondence in the existing stored
calibration data, it is added to it if this is not full, or the instrument will
ask which buffer will be replaced by the current buffer.
If at least a two-point calibration has been performed and an offset
correction of the electrode is desired, keeping unchanged the existing
slopes, perform a one-point calibration with “OFFS” option selected in
SETUP menu. If “Pnt” option is selected, the slopes adjacent to the
calibration points will be reevaluated.
FIVE-POINT CALIBRATION
• Immerse the pH electrode and the temperature
probe approximately 4 cm (1½”) into a buffer
solution of your choice (pH 1.68, 4.01, 6.86, 7.01,
9.18, 10.01, 12.45, custom buffer 1 or 2, if these
were set) and stir gently. The temperature probe
should be close to the pH electrode.
• Press CAL. The “CLEAR CAL IF NEW ELECTRODE”
message will be displayed blinking on the LCD for a
few seconds if the instrument was calibrated before
and calibration was not cleared.
Press CLR if you are using a new electrode or want to clear calibration
history, or wait a few seconds to continue.
Press CAL again or the ARROW keys to skip this message.
Note: It is very important to clear calibration history when a new
electrode is used because most errors and warning messages
that appear during calibration depend on calibration history.
• The instruments will display the measured pH on the primary LCD and
the “7.01” buffer on the secondary LCD, together with “CAL” and “Cal
Point 1” tags and “7.01” tag blinking.
• If necessary, press the ARROW keys to select a different buffer value.
CAL