Abstract

A sensor utilizes the opposition of a fluid to physical displacement to provide information about the fluid itself, such as its quality as measured by its density or viscosity, or about the state of a fluid system which contains it, such as the fluid pressure existing at some point in the system. The sensor includes a fluid displacement device or element physically adapted to displace the fluid and repetitively urged into displacement by the application of a known impetus or urging force. The resulting motion of the element is then analyzed to obtain the information desired. The fluid displacement element may additionally perform a pumping function, or it may operate in a fluid stream externally powered. When employed as a pump, the sensor may provide information on the fluid pumped or on the state of the fluid system.