In-line extraction of rheological flow curves at constant production rate

A simple experimental technique to extracting the static rheological properties of manufacturing fluids at constant production rate is presented in this work. The method is based on the principle of the rectilinear pipe viscosimeter, and it is thought be inserted directly in the main production line. By means of a system of parallel pipes interconnected together with a convenient combination of butterfly valves (which are accordingly regulated to redistributing the flow) the flow curve can be built upward on one tube and downward on the other. A pilot experimental facility allowed to testing the feasibility of such an idea on some real food fluids (fruit purees both raw and 10% in volume diluted with water) showing a marked non-Newtonian behaviour. Additional experiments were also made, by varying the fluid temperature. The experiments made up on different pipe diameters confirmed the absence of anomalous flow conditions and, in turn, the reliability of the results. These latter are encouraging and show the usefulness of this technique, which could be easily coupled with the recent UVPPD method so to obtain real time monitoring. Additional experiments aiming at automating the whole process, as well as testing this system on a real production line are foreseen.