Instrumentation and monitoring systems utilize, as differential temperature sensors, heated, split-well thermowells of duplex design, mounted to the sidewall of a pressure vessel and communicating through a penetration in the sidewall with the fluid state within the vessel. Each probe has at least one...http://www.google.de/patents/US4901061?utm_source=gb-gplus-sharePatent US4901061 - Instrumentation and monitoring systems employing differential temperature sensors
