Hanna Instruments HI 221 - Manual (Page 15)

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GLP is a set of functions that allows the storage and retrieval of data regarding
the maintenance and status of the electrode.
All data regarding the last calibration (one or two points) is stored for the user
to review when necessary. This data includes the following: calibration time
stamp, offset (in mV), slope (in mV/pH), electrode condition and response
gauges, calibration buffers and the amount of time until a new calibration is
required.
CALIBRATION ALARM TIME-OUT
HI 221 and HI 223 allow the user to set the number of days before the next
required pH calibration. This value can be set from 1 to 7 days. The default
value is OFF (disabled).
The instrument checks if the time-out time has expired. If the time has
elapsed, the CAL DUE will blink as a reminder.
Note: If the instrument was not calibrated, or if the calibration history was
deleted, the CAL DUE message will be displayed even if this feature is
disabled in the SETUP menu.
If the instrument was calibrated using an electrode with pin and the
electrode is changed with an electrode without pin or vice-versa CAL
DUE will blink. This feature helps ensure use of a calibrated instru-
ment.
LAST CALIBRATION DATA
Last calibration data is stored automatically after a successful calibration.
To view the pH calibration data, press the GLP key when the instrument is in
pH measuring mode.
The instrument will display the time of the last calibration.
Press the ARROW keys to view the following logged calibration parameters
(pressing the / ºC key):
_ The time (hh:mm).
GOOD LABORATORY PRACTICE (GLP)
Also, when the instrument cannot evaluate the electrode response or pH 1.68 or
pH 12.45 buffer were used as calibration buffer, the response gauge will be empty.
If the electrode is in a very poor condition the first condition segment will blink.
If electrode response is very slow the first response segment will blink.