G 1409
Measurement Basics | 5
B-H87.0.01.DB2-2.1
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5
Measurement Basics
5.1
Conductivity principles
Conductivity γ
Conductivity describes the capability of a material to conduct electrical current. It is al-
so the inverse of specific resistance. The conductance is the inverse of the measured
resistance R.
γ = l / (R*A)
l = length of the material
A = cross section
R = measured resistance
Unit [γ] = Siemens / metre = S / m
Normally, the values for liquids are specified in µS/cm or in mS/cm.
5.2
General information about conductivity
measuring
During the measurement, the conductivity measuring cell must be dipped at least in so
far, that at least 30 mm beginning from the top of the measuring cell, is located in the
medium. The maximum immersion depth for continuous operation should not exceed
110 mm
The measuring cell can either be stored dry or in water. After dry storage, wetting time
will be prolonged slightly. If changing over from one liquid to another with conductivi-
ties varying widely make sure to properly rinse and shake dry measuring cell.
If conductivity measured is much higher or lower than expected this may be due to the
electrode being soiled with non-conducting or conducting foreign materials. Measuring
cell has to be cleaned with a watery soap solution. When measuring media with low
conductivities the electrode has to be stirred sufficiently.
NOTE
Measuring cell must never come into contact with water-repellent materials such as oil
or silicone.
5.3
Conductivity measurement
The conductivity measurement is a comparatively uncomplicated measurement. The
standard electrodes are stable for correct use for a long time and can be calibrated
over the gradient correction.
Formula
