Xylem CG 843 - Manual (Page 28)

Operation
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4.3.1 Calibration interval (Int 3)
The flashing sensor symbol reminds you to calibrate regu-
larly. After the selected calibration interval (Int 3) expires,
the sensor symbol flashes. Measurements can continue.
Note
To ensure the high measuring precision of the measuring
system, perform a calibration after the calibration interval
expires.
Setting the calibra-
tion interval
The calibration interval (Int 3) is set to 7 days in the factory.
The interval can be changed (1 ... 999 days):
1 Switch off the instrument.
2 Press <pH> and hold down the key.
3 Press the <on/off> key.
The display test appears briefly on the display.
The instrument then switches automatically to the
configuration level.
4 Press the <run/enter> key until Int 3 appears on the
display.
5 Press < ▲ > < ▼ > to set the required time interval until
the next calibration.
6 Confirm with <run/enter>.
7 Change to the measuring mode by pressing <pH>.