Thermo Fisher Scientific CyberScan PC 5000 - Manual (Page 171)

Instruction Manual CyberScan PC5500/ 5000
166
Conductivity Measurement
Conductivity electrodes consist of glass or epoxy bodies in which
platinum or platinised sensing elements and are designated two-cell
electrode has two such sensing elements and are designated two-cell
electrodes. The previous discussion has focused on this type of
electrode. Four cell electrodes are also available, and the theory and
application of these are in a separate section.
These sensors contact the solution whose conductivity value is
sought. The exact cell constant of the electrode must be determined
prior to measuring the sample. In essence, this is accomplished by
fixing the nominal cell constant of the electrode into the meter, and
recording the observed conductivity value associated with a standard
conductivity solution (usually a KCI solution) with a precisely known
value. The following calculation yields the actual cell constant.
K= standard value of solution (uS)/ observed value of solution (uS)
Fortunately, this CyberScan meter automatically does this calculation
for you by touching the std button.
To produce an appropriate current signal for the meter it is important
to choose an electrode with an appropriate cell constant. The
following table lists the optimum conductivity ranges for electrodes
with cell constants of 0.1, 1, and 10.
Cell Constant
Optimum Conductivity Range
2-cell
0.1
1.0
10.0
0.5 to 200 µS/ cm
0.01 to 2 mS/ cm
1 to 200 mS/ cm
Prior to use the electrodes should be conditioned in distilled or
deionized water for at least 10 minutes or in accordance with the
manufacturer’s instructions.