A sensor for measuring the height of fluid in a vessel, the sensor including a mounting base shaped to be coupled to an exterior surface of a vessel. The sensor further includes a transducer having a pulse source for sending pulses into the vessel and an echo detector for detecting echoes of pulses emitted...http://www.google.co.uk/patents/US6412344?utm_source=gb-gplus-sharePatent US6412344 - Fluid level sensor with dry couplant
