Transmitter with isolation assembly for pressure sensor
First Claim
1. A transmitter for providing an output indicative of a pressure of a process fluid, comprising:
- a transmitter housing;
transmitter circuitry in the transmitter housing for providing the output in response to a sensor output;
a sensor coupling coupled to the transmitter housing defining a sensor cavity having a cavity volume filled with isolation fluid, the sensor coupling having a first thermal expansion coefficient;
an isolation diaphragm coupled to the sensor coupling and defining the sensor body therein, the isolation diaphragm adapted to couple the pressure to the isolation fluid;
a pressure sensor mounted in the sensor cavity and coupled to the isolation fluid, the pressure sensor providing the sensor output to the transmitter circuitry; and
a thermal compensation member coupled to the cavity having a second thermal expansion coefficient to compensate for changes in the cavity volume due to thermal expansion of the sensor coupling.
1 Assignment
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Accused Products
Abstract
A process control transmitter includes a transmitter housing and transmitter circuitry adapted for providing a transmitter output related to a sensed pressure. A sensor coupling in the housing defines a pressure sensor cavity which is filled with isolation fluid. An isolation diaphragm separates the sensor cavity from a process fluid and is adapted to transmit pressure therebetween. The pressure sensor is mounted in the sensor cavity and provides an output related to pressure to the transmitter circuitry. A thermal compensation member is coupled to the sensor cavity and has a thermal expansion coefficient which is different than a thermal expansion coefficient for the sensor coupling. The compensation member is adapted to compensate for pressure changes due to thermal expansion of the components or isolation fluid.
134 Citations
12 Claims
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1. A transmitter for providing an output indicative of a pressure of a process fluid, comprising:
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a transmitter housing; transmitter circuitry in the transmitter housing for providing the output in response to a sensor output; a sensor coupling coupled to the transmitter housing defining a sensor cavity having a cavity volume filled with isolation fluid, the sensor coupling having a first thermal expansion coefficient; an isolation diaphragm coupled to the sensor coupling and defining the sensor body therein, the isolation diaphragm adapted to couple the pressure to the isolation fluid; a pressure sensor mounted in the sensor cavity and coupled to the isolation fluid, the pressure sensor providing the sensor output to the transmitter circuitry; and a thermal compensation member coupled to the cavity having a second thermal expansion coefficient to compensate for changes in the cavity volume due to thermal expansion of the sensor coupling. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification