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Conductivity Measurement
Accumet 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 accumet AB30 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
0.1
1.0
10.0
Prior to use, the probes should be conditioned in distilled or
deionized water for at least 10 minutes or in accordance with the
manufacturerÕs instructions.
Optimum Conductivity Range (µS/cm)
0.5 to 200
10 to 2000
1000 to 200,000
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