Hanna Instruments HI 98150N - Manual (Page 18)

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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 or Rel mV calibration is stored for the user to
review when necessary.
HI 98140 and HI 98150 use electrodes with built-in EEPROM in which
calibration data is read at start up and stored after calibration. The
meter can automatically analyze the data and advise the user during
measurements if a problem is found with a clear message.
If the calibration offset is outside ±30 mV window, “
OLD Probe” tag is
displayed blinking to warn user to perform a cleaning procedure.
If the calibration offset is outside ±60 mV window “
DEAD Probe” tag
is displayed blinking to warn the user that readings are not reliable.
EXPIRED CALIBRATION
The instrument is provided with a real time clock (RTC), 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” tag 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 21) from
OFF (function disabled) to 7 days.
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” tag blinking.
• When an abnormal condition in the RTC 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
2nd then
GLP when the instrument is in pH measurement
mode.
The instrument will display the date (mm.dd)
and the time (hh:mm) of the last calibration.
The “condition” bargraph remains active until the end of the calibration day.