October 2020

| 30 | September/October 2020 www.smartmachinesandfactories.com | TECHNOLOGIES | A utomation systems in the food manufacturing and processing sector depend on data from huge numbers of sensors. The most important parameters monitored by these sensors include pressure, temperature, flow and level. Many of the specifications for these sensors are the same as those in any other process industry but, in the food sector, hygienic design is often an additional and critical requirement. And in some cases, the sensors must also be suitable for use in hazardous areas. Sensors with added value Many sensor products are now available in hygienic versions designed specifically for food industry applications, and leading manufacturers of these sensors are increasingly focussing their development efforts on applying innovative technology to provide added value for users of their products. A good example of these innovations is a new generation of level sensors that operate on the guided wave radar (GWR) principle. GWR sensors are installed vertically at the top of a tank and emit high frequency electromagnetic pulses that are guided downwards along a stainless-steel rod. These pulses are then reflected from the surface of the medium back towards the sensor. The transit time of the pulses is used to evaluate the distance to the surface and thus the level in the tank. This measuring technology provides important benefits over other types of level sensors. GWR sensors are unaffected by changing media (provided that the dielectric constant >5), changing temperature, gas blankets or vapours, or by build-up of product on the probe itself. In addition, they can accurately and reliably measure liquid levels in many foaming applications. The probes for the food-industry versions of these innovative sensors are made of high-grade stainless steel and all other components follow hygienic design principles to meet the requirements of EHEDG. Probes with different lengths are available and can be easily interchanged by the user to meet the needs of the application. The probes can also be cut to length if no suitable standard length is available. This modular design maximises versatility and reduces costs. The best of these sensors also has an IO-Link interface. Another example of sensors that The food industry often presents challenging environments for components and, in particular, for the sensors used in process control applications. In addition, users’ expectations of sensor technology are continually increasing. These considerations mean that the future belongs to smart sensors that not only offer outstanding performance and reliability but also deliver substantial added value, says Andy Walker of ifm electronic. The future belongs to smart sensors Many processes in the food industry require accurate control of the temperature of fluids