Xylem handylab LF 11 - Manual (Page 20)

Operation handylab LF 11
20 ba75365e04 01/2011
4.3 Determining/setting up the cell constant [C]
Why determine/set
up the cell
constant?
Aging slightly changes the characteristics of the cell, e. g. by coatings. As a
result, an inexact measured value is displayed. The original characteristics of
the cell can often be restored by cleaning the cell. Calibration determines the
current cell constant and stores it in the instrument.
Thus, you should calibrate at regular intervals (we recommend: every 6
months).
Procedure The cell constant is determined in the control standard, 0.01 mol/l KCl.
You can determine the actual cell constant of the conductivity measuring cell
by calibrating with the control standard in the following ranges:
z 0.450 ... 0.500 cm -1
z 0.800 ... 1.200 cm -1
Besides, you can set the cell constant manually in the following ranges:
z 0.090 ... 0.110 cm -1
z 0.250 ... 2.500 cm -1
The fixed cell constant, 0.010 cm
-1
can also be selected. It is not necessary
to calibrate or adjust it.
Cell constants outside the above mentioned ranges cannot be calibrated.
Calibration
evaluation
After the calibration, the measuring instrument automatically evaluates the
current status of the calibration. The evaluation appears on the display.
Display Cell constant [cm
-1
]
0.450 ... 0.500 cm
-1
0.800 ... 1.200 cm
-1
E3
Eliminate the error according to
chapter 6 W
HAT TO DO IF ...
outside the ranges
0.450 ... 0.500 cm
-1
or
0.800 ... 1.200 cm
-1