The current AQUATRAC product range symbolizes state of the art, together with the Brabender attributes robustness, suitability for everyday industrial use and outstanding service. Here we explain our measuring methods in detail.
It is also well known that chemical methods such as Karl Fischer titration are too costly for rapid residual moisture analysis in hectic industrial environments. With the water-selective dew point measurement, Brabender now adds another, extremely precise method to the residual moisture determination by means of calcium hydride.
Water and calcium hydride react with each other to form hydrogen; following reaction equation: CaH2 + 2 H2O → Ca(OH)2 + 2 H2 In the AQUATRAC-V this reaction takes place in a closed vessel, the reaction vessel. It is evacuated by a built-in vacuum pump before the measurement and electrically heated during the measurement. The water vapor released by the heating reacts with the calcium hydride, and the pressure in the measuring system increases due to the developing hydrogen. The gas pressure is proportional to the amount of water introduced, because the reaction is specific for water. The gas pressure is the measured variable of this method. The ratio of water quantity and sample weight is calculated, and the result is displayed in %, ppm and mg water content. Other volatile substances are condensed in a cold trap at room temperature and therefore do not participate in the measurement. Therefore, this is an absolute measuring method exclusively for water as also described in the standard DIN EN ISO 15512:2019 as method E – determination of the water content by the calcium hydride method.
Calcium hydride in granular form is used as water-specific reagent. It is non-toxic and environmentally friendly, so that no costly disposal is necessary. The reagent is filled into the reagent insert in the AQUATRAC-V with the aid of a metering spoon. Contrary to conventional handling, only approx. 0.3 g of calcium hydride is now added for each measurement and replaced during the next measurement. This makes using the AQUATRAC-V even more intuitive. In addition, the amount of hydrogen produced is guaranteed to be minimal for each measurement.