Transmitter with isolation assembly for pressure sensor

摘要

A process control transmitter (10) includes a transmitter housing (12) and transmitter circuitry (20) adapted for providing a transmitter output related to a sensed pressure. A sensor coupling (42) in the housing (12) defines a pressure sensor cavity which is filled with isolation fluid. An isolation diaphragm (46) separates the sensor cavity from a process fluid and is adapted to transmit pressure therebetween. The pressure sensor (16) is mounted in the sensor cavity and provides an output related to pressure to the transmitter circuitry (20). A thermal compensation member (44) is coupled to the sensor cavity and has it thermal expansion coefficient which is different than a thermal expansion coefficient for the sensor coupling (42). The compensation member (44) is adapted to compensate for pressure changes due to thermal expansion of the components or isolation fluid.