Hanna Instruments HI 3220 - Manual (Page 29)

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GOOD LABORATORY PRACTICE (GLP) GOOD LABORATORY PRACTICE (GLP) GOOD LABORATORY PRACTICE (GLP) GOOD LABORATORY PRACTICE (GLP) GOOD LABORATORY PRACTICE (GLP)
GLP is a set of functions that allows storage and retrieval of data regarding the
maintenance and status of the electrode.
All data regarding pH, Rel mV or ISE calibration is stored for the user to review
when necessary.
EXPIRED CALIBRATION
The instrument is provided with a real time clock (RTC), in order to monitor
the time elapsed since the last pH calibration.
The real time clock is reset every time the instrument is calibrated and the
“expired calibration” status is triggered when the instrument detects a
calibration time out. The “CAL” “DUE” warning will start blinking to warn
the user that the instrument should be recalibrated.
The calibration time out can be set (see SETUP for details, page 31) from 1 to
7 days or can be disabled.
For example, if a 4 days time out has been selected, the instrument will issue
the alarm exactly 4 days after the last calibration.
However, if at any moment the expiration value is changed (e.g. to 5 days),
then the alarm will be immediately recalculated and appear 5 days after the
last calibration.
Notes: • When the instrument is not calibrated or calibration is cleared
(default values loaded) there is no “expired calibration”, and
the display always shows the “CAL” “DUE” warning blinking.
• When an abnormal condition in the RTC (Real Time Clock) is
detected, the instrument forces the “expired calibration” status.
LAST pH CALIBRATION DATA
The last pH calibration data is stored automatically after a successful calibration.
To view the pH calibration data, press GLP function key when the instru-
ment is in the pH measurement mode. If GLP function key is not displayed
press MENU key.
The instrument will display a lot of data including calibration buffer, offset,
slope, electrode condition.
Note: Buffers displayed in video inverse mode are from previous calibrations.
The custom buffers are marked with an “
* ” on the right side of the buffer value.
“No user calibration” message is displayed if all calibration are cleared or
the instrument was not calibrated in the pH range.