A fluid level sensor for determining the amount of liquid in a container. Thin metal plates are placed parallely adjacent each other to form a capacitor cell coated with a non-hygroscopic film. The plates are mounted on the walls of the container containing fluid. As the fluid covers more surface area...http://www.google.co.uk/patents/US4982606?utm_source=gb-gplus-sharePatent US4982606 - Fluid level sensor and controller
