optek's Conductivity Design
The Evolution of Conductivity 2.0
Six-electrodes, four-pole design + integrated electronics
While standard sensors for conductivity have a cable connection between sensing elements and measurement electronics, this new design has advanced electronics integrated into the sensor. This eliminates the influence of the cable (resistance and capacitance), allowing for a highly accurate response over a wide conductivity range. Having 4 electrodes for the applied current and 2 electrodes measuring the resulting voltage, the electrical field lines have an optimal distribution between the poles and minimize effects on the voltage measurement.
Inside the new 6 electrode 4 pole sensor an improved electronics with a 16 bit A/D converter ensures a stable, reproducible and highly accurate measurement of conductivity in a wide range of 0…10 µS/cm up to 850 mS/cm. Due to high quality electrode materials, degradation of the electrode surface is negligible. Both leads to a long lasting cell constant (typically 0.35 cm-1). Finally, with this 6 electrode sensor design only one calibration point is necessary, whereas other sensor designs require several calibration points.
From conductivity signal to output value
A Pt1000 temperature sensor integrated in the tip of the sensor is used to compensate temperature based conductivity changes during calibration and measurement. Although the sensor gets a factory calibration, it is recommended to perform a user calibration in the final installation setup, preferably using a calibration standard having a conductivity value within the desired measurement range. This ensures the best sensor performance and measurement accuracy at the final installation location.
Sensor accuracy optek ACF60 and ACS60
Following are the measurement range dependent accuracies with corresponding reproducibility:
|0 - 10 μS/cm||± 1% of measurement ± 0.2 µS/cm
|0 - 250 mS/cm||± 1% of measurement ± 0.2 µS/cm
|250 - 500 mS/cm||± 2% of measurement ± 0.2 µS/cm
|500 - 850 mS/cm||± 5% of measurement ± 0.2 µS/cm
Example: Measurement result is 20 µS/cm. 1% of measurement is +/- 0.2 µS/cm plus +/- 0.2 µS/cm. The measurement result accuracy is therefore 20 µS/cm +/- 0.4 µS/cm.