Thermo Fisher Scientific CyberScan CON 1500 - Manual (Page 66)

Instruction Manual CyberScan CON 1500
62
Conductivity Measurement
CyberScan conductivity probes 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 ( µS)/ observed value of solution (µS)
Fortunately, the CyberScan CON 1500 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 ( µS/cm)
0.1
1.0
10.0
0.5 to 200
10 to 2000
1000 to 200,000
Prior to use, the probes should be conditioned in distilled or deionised
water for at least 10 minutes or in accordance with the
manufacturer’s instructions.