Device for checking the level of a liquid in a tank

摘要

A device for checking the level of a liquid in a tank, for example a car fuel tank, has an electrical resistance probe partly immersed in the liquid and energized with a constant current. The voltage across the probe at switching on is stored and used as a reference for comparing with the increased voltage after the element has been heated to a value dependent on the length of resistor cooled by the liquid.