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Operation
Why determine the cell
constant?
Procedure
Stability control
(AutoRead)
Display calibration data
Calibration evaluation
30
4.4.5 Determining the cell constant (calibration in
control standard)
Aging slightly changes the cell constant, e.g. due to coatings. As a
result, an inexact measured value is displayed. The original character-
istics of the cell can often be restored by cleaning the cell. Calibration
determines the current value of the cell constant and stores this value
in the meter.
Thus, you should calibrate at regular intervals (we recommend: every
6 months).
You can determine the actual cell constant of the conductivity measur-
ing cell by calibrating with the control standard in the following ranges:
0.450 ... 0.500 cm
(e.g. LF413T, nominal cell constant 0.475 cm
0.800 ... 0.880 cm
(e.g. conductivity measuring cells with a nominal cell constant of
-1
0.840 cm
)
The cell constant is determined in the control standard, 0.01 mol/l KCl.
Cell constants outside the ranges quoted above cannot be calibrated.
In the default condition, the calibrated cell constant of the meter is set
-1
to 0.475 cm
(conductivity sensor LF413T).
In calibration, the Stability control function (AutoRead) is automatically
activated.
You can have the data of the last calibration displayed (see section
4.4.6).
After calibration, the meter automatically evaluates the current status of
the calibration. The evaluation appears on the display and in the cali-
bration record.
Display
Calibration
record
+++
-1
-1
Cell constant [cm
within the ranges
0.450 ... 0.500 cm
or
0.800 ... 0.880 cm
HandyLab 200
-1
)
-1
]
-1
-1
ba77063e03
01/2018
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