The measuring and control system for improved model based diastat filling quality

The article describes the development and testing of a measurement and control system in industrial environment. This system enables fast and accurate membrane expansion measurements. The membrane is part of the sensor system called diastat, which is filled with a special oil. The diastat is part of mechanical capillary thermostat. To demonstrate the right selection of the measurement equipment and data processing methods, several tests and analysis were performed: the dynamic response of the diastat membrane during filling, measuring accuracy, nonlinearity and temperature stability of the measurement system with integrated distance sensor and the most important verification measurements with reference control procedures in manufacturing process. It was demonstrated that a number of novel approaches need to be introduced enabling installation of the measurement and control system in the production of the thermostat diastats.

► The system is used for control of the thermostat membranes filling with special oil. ► Several measurement approaches of diastat expansion was tested. ► For better measurement performance a non-linearity compensation was implemented. ► The measurement system enables accurate measurements in dirty industrial environment. ► The quality of developed system was verified by reference quality control.