Flow sensor for viscous foodstuffs

Problem: . Producers of highly non-Newtonian fluids, for example, who manufacture highly viscous products such as tomato ketchup, chocolate, ready meals, pasta sauce and curry sauce, have found it virtually impossible to achieve real time control due to the non-uniform nature of the food, which may contain particulates, fibres, vegetables, meat, nuts, raisins or biscuits. Solution: Research currently taking place at University College Dublin is helping to solve these problems. At the heart of the viscosity measurement system is a Torqsense transducer supplied by Sensor Technology based in Oxon. This device monitors the constantly changing flow characteristics and mixability of the materials. Torqsense uses Surface Acoustic Waves (SAW) techniques to provide non-contact monitoring of instantaneous rotary torque, allowing accurate modelling of the instantaneous load changes. The device is basically a frequency-dependent strain gauge operating at ultrasound frequencies and consists of a transducer mounted on the mixer’s rotating shaft to monitor variations in its resonant frequency as the torsional load varies. An RF link is used for wireless transmission of signals to an adjacent pick-up so that rotation is unhindered. Applications: Research team leader at University College Dublin, PJ Cullen told Eureka that: “The system had to be able to detect changes with sufficient sensitivity, yet also be robust enough for regular wash-downs and general industrial abuse.” He also claimed the system is “low cost, reliable and simple to use.” The system is suitable for a wide range of food manufacturing industries, particularly in full scale process control environments. DP