VWR International MU 6100 H, Instruction Manual

Page: 49 / 96

MU 6100 H Conductivity
ba77077e02 09/2014
49
9.2 Calibration
9.2.1 Why calibrate?
Aging slightly changes the cell constant, e.g. due to 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 value
of the cell constant and stores this value in the meter.
Thus, you should calibrate at regular intervals (we recommend: every 6
months).
9.2.2 When to calibrate?
 After connecting a sensor
 Routinely within the framework of the company quality assurance
 When the cleaning interval has expired
9.2.3 Determining the cell constant (calibration in control standard)
You can determine the actual cell constant of the conductivity measuring cell
by calibrating with the control standard in the following ranges:
The cell constant is determined in the control standard, 0.01 mol/l KCl. Cell
constants outside the ranges quoted above cannot be calibrated.
For this calibration procedure, the Measuring cell setting must be set to cal in
the Measurement menu. Proceed as follows to determine the cell constant:
 0.800 ... 0.880 cm
-1
(e.g.
CO 11
with a nominal cell constant of 0.840 cm
-1
)
 0.450 ... 0.500 cm
-1
(e.g.
conductivity measuring cells
with a nominal cell constant of
around
0.475 cm
-1
)
In the default condition, the calibrated cell constant of the meter is set to
0.840 cm
-1
(conductivity measuring cell
CO 11
).
1. Connect the conductivity measuring cell to the measuring instrument.
2. In the measured value display, select the conductivity parameter with
<MODE> .
3. Start the calibration with <CAL> .
The cell constant that was calibrated last is displayed.