Xylem handylab pH LF 12 - Manual (Page 39)

handylab pH/LF 12 Operation
39 ba75370e03 11/2009
4.4.5 Determining the cell constant (Calibration in the
control standard)
Why determine the
cell constant?
Aging slightly changes the cell constant, e. g. by coatings. As a result, an in-
exact measured value is displayed. The original characteristics of the cell can
often be restored by cleaning the cell. Calibration determines the current val-
ue of the cell constant and stores this value in the instrument.
Thus, you should calibrate at regular intervals.
In the delivery condition, the cell constant of the measuring instruments is set
to 0.475 cm
-1
.
AutoRead The calibration procedure automatically activates the AutoRead function.
The AR display indicator flashes. The calibration process is finished when AR
stops flashing.
Displaying
calibration data
You can view the data of the last calibration on the display. The proceeding
is described on page 53.
Printing the
calibration
protocol
The calibration protocol contains the calibration data of the current calibration.
You can transmit the calibration protocol to a printer via the serial interface
(see page 55).
Note
You can automatically print a calibration protocol after the calibration. To do
so, connect a printer to the interface according to section 4.7.2 before cali-
brating. After a valid calibration, the record is printed.
Sample printout:
CALIBRATION PROTOCOL
14.04.01 11:37
Device No.: 99990000
Calibration Conductivity
Cal time: 14.04.01 / 11:37
Cal interval: 180d
Cal Std.: 0.01 mol/l KCL
40.0 °C
Conduct./Tref25: 1413µS/cm
Cell Const : 0.478 1/cm
Probe : +++