Process Analysis

Easy In-line Moisture Measurement Without Elaborate Calibration

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The samples taken are analysed in the laboratory using either Karl Fischer titration or Loss On Drying. The laboratory values are then correlated with the measured values: two parameters are deduced from this and fed into the sensor. After this adaptation of the parameters, the sensor is equipped to measure the moisture values very accurately, achieving absolute moisture readings to within approx. ±0.12 percent.

Which Steps Are Required for Calibration

The calibration has to be carried out for each formulation. The work involved is however minimal and is limited to taking samples while doing a normal drying till the end-point. For 100 percent reliable sensor operation, it is necessary for the observation window to be cleaned before the measurements are made, guaranteeing that the readings reach the required precision, normally fixed in advance by a CpK value.

This moisture sensor, with integrated process interface lighthouse probe manufactured by GEA, provides the required reliability and needed automation. To achieve maximum accuracy, the sensor is moved (manually or pneumatically) into the measurement position before each measurement. As long as no measurement is required, the sensor remains in a parked position where the observation window is positioned outside the process space.

Keep the Observation Window Clean!

As a result, the observation window is kept clean until a measurement is required and the measurement can be completed without risk of window fouling. For continuous measuring, an inverse process is possible. Here the observation window is brought back cyclically into the parked position for cleaning.