Process Refractometer Offers Universal Measuring

The process refractometer PR21 of A. Krüss Optronic is a universal measuring instrument for determining the refractive index and therefore the concentration of a substance in liquid in a temperature range of -6 to +160°C. It can be installed into the walls of pipes, cauldrons or storage tanks without having to observe any special requirements. This allows controlling and managing processes, for instance monitoring the purity of liquids or concentration of solutions by carrying out measurements in the production plant itself. It is possible to digitally programme the PR21 using a PC, in order to adapt it to the specific respective application. It can be connected directly to computers via Ethernet or an optional profibus interface, in order to record measured values or to control the process. A further option is the use of a display during operation that can be installed at the measuring site or on an instrument panel in the control room. The universality and flexibility of the PR21 make it an integral part of the production plant.

The PR21 uses a LED with a wavelength of 589.3 nm as source of light. This corresponds to the sodium D line. The measuring range spans 1.33 to 1.70 nD, allowing programming of an applicationspecific measurement range of 0.15 nD. Two versions with different measuring accuracies are available. The standard version measures precisely down to 0.0002 nD, corresponding to 0.1% Brix, the high precision version PR21H to 0.00002 nD respectively 0.02% Brix. The temperature range of both PR21 versions extends from -4°C to +60° C. Both versions are also available in a water-cooled version for high temperature measurements up to 160°C. The PR21 can be used both for individual measurements as well as for periodic interval measurements. In the basic model, correction scales for saccharose, inverse sugar, glucose, and fructose are pre-programmed. On request, A. Krüss Optronic can also supply differently programmed versions. This allows the device to be used immediately without reprogramming. It is furthermore very easy to program the PR21 for any material in the field.