Improving Product Level Sensing in Filling Tubes

Sammanfattning: This thesis examines the possibility to improve the product level sensing in one of Tetra Pak’s filling machines, because the current solution does not detect this with the desirable precision, as well as measuring range. Today, a magnetic float is used together with 16 separate capacitive sensors. The issue with this is that packages get rejected due to a faulty amount of product. This occurs because of two factors, one being that the precision is too low, due to an insufficient amount of sensors, and because a device floating on the liquid’s surface is used to measure the product level, and its position does not always correspond to the actual level. The methods include researching currently used measuring techniques, determining which of them that are adaptable in the context, ascertaining the needs and requirements of a well-suitable solution in a hygienic food industry environment, and testing the suggested new measuring technique. The results showed that using a magnetic position sensor with a float was a suitable solution, if it is combined with a cover, as the sensor needs to be protected from the strong detergents used to clean the filling machines. Though, adaptations of the sensor calibration and cable are needed to fulfil the requirements. The advantages of the new solution are that it gives a very high resolution and that the whole range of the filling tube can be measured. The major disadvantage is that there is still a need for a float, which requires frequent cleaning to obtain a high hygiene standard and can give incorrect signals due to oscillation.