Hanna Instruments HI 255 User Manual
Page 14
14
Note: If the value measured by the instrument is not
close to the selected buffer, WRONG
2
BUF
and WRONG tags will blink alternately.
In this case, check if the correct buffer has been
used or regenerate the electrode by following the Cleaning Proce-
dure (see page 45). If necessary, change the buffer or the
electrode.
If WRONG, Buffer pH tags and Old tag on secondary LCD are
displayed blinking, an inconsistency between new and previous
(old) calibration is detected. Clear calibration parameters by
pressing LOCK/CLR and proceed with calibration from the
current calibration point (the instrument will keep all confirmed
values during current calibration).
If LOCK/CLR is pressed at the first calibration point, the instru-
ment clears all calibration parameters and returns to measurement
mode.
The WRONG tag and temperature value are displayed blinking
if temperature reading is out of the defined temperature range of
the buffer. Calibration cannot be confirmed in this situation.
Press RANGE to display the temperature reading
on the LCD during calibration.
TWO-POINT CALIBRATION
Proceed as described in Three-point calibration section.
Press CAL after the second calibration point was confirmed.
The instrument will return to measurement mode and will memorize the
two-point calibration data.
ONE-POINT CALIBRATION
Proceed as described in Three-point calibration section.
Press CAL after the first calibration point was confirmed.
The instrument will return to measurement mode and will memorize the
one-point calibration data.
Note: Calibration parameters are evaluated taking in consideration the new
values for the confirmed buffers in current calibration and the old
values, if existing, for the other buffers. To clear old calibration values,
press LOCK/CLR before exiting calibration.