Hanna Instruments HI 250 - Manual (Page 12)

12
Note: • If the value measured by the instruments is not close to the
selected buffer, “WRONG” “
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 30). If necessary, change the buffer or the
electrode.
• If “WRONG”, “Buffer pH” tags and “Old” tag on the secondary LCD
are displayed blinking, an inconsistency between new and previous
(old) calibration is detected. Clear calibration parameters by
pressing SET/CLR and proceed with calibration from the current
calibration point (the instruments will keep all confirmed values
during current calibration).
• 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 instruments 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 instruments 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 SET/CLR before exiting calibration.