Hanna Instruments HI 221 - Manual (Page 12)

12
CAL
BUFFER 1
pH
ELECTRODE CLEAN
ATC
ATC
The stored calibration history to used issue error and warning messages during
calibration to help ensure the highest accuracy.
As electrode aging is normally a slow process, substantial changes from
previous calibrations are likely due to a temporary problem with the electrode
or buffers. Calibrating under these conditions will give measurement errors.
ERROR MESSAGES
Error messages appear if one or all of the calibration parameters are out of
accepted windows. When these messages are displayed calibration cannot be
confirmed.
WRONG BUFFER
This message appears when the difference between the pH reading and the
value of the selected buffer is too big. If this error message is displayed, check
if you have selected the proper calibration buffer.
CLEAN ELECTRODE
This error message indicates a bad electrode condition (offset out of accepted
window, or slope under the accepted lower limit).
Clean the electrode according to the Cleaning Procedure on page 32 to
improve its condition and repeat the calibration. This ensures the removal of
film, dirt or deposits on the glass bulb and reference junction.
CHECK ELECTRODE alternating with CHECK BUFFER
This error message appears when electrode slope exceeds the highest accepted
slope limit. You should check your electrode and use fresh buffer.
ATC
ENHANCED CALIBRATION MESSAGES