The electric functioning of the flow sensor is based on the calorimetric principle. The temperature of the measurement sensor is raised from its inner with some degrees Celsius in relation to the temperature of the flowing medium into which the sensor is projecting. If the medium is flowing, the heat produced in the sensor is dissipated through the medium, i.e. the sensor is cooled down. The temperature that ensues in the sensor is measured and compared to the registered medium temperature. The state of flow of the medium can be derived from the registered temperature difference.
By means of a novel type of electric and mechanic design, the probe is made of special steel and is designed in one single piece. This way, it has been possible to achieve complete impermeability and high resistance to pressure. In corrosive media, especially in oxidative media, special steel is conditionally stable. The sensor should be made of, at least, the same material as the one used for this medium.