Abstract: A pressure sensor assembly for sensing a pressure of a process fluid includes a sensor body having a cavity formed therein to couple to a process fluid pressure. A deflectable diaphragm in the cavity deflects in response to the first and second process fluid pressures. A first primary electrode couples to a wall of the cavity and forms a first primary capacitor between the first primary electrode and the deflectable diaphragm. A first secondary electrode couples to the wall of the cavity to form a first secondary capacitor between the first secondary electrode and the deflectable diaphragm. A second primary electrode and second secondary electrode are preferably coupled to a wall of the cavity opposite the first. Line pressure of the process fluid is determined based upon variation in the secondary capacitors relative to the primary capacitors.

Abstract: A diagnostic system for a pressure sensor having a cavity configured to receive on applied pressure is provided. The cavity has a first and a second wall. A deflectable diaphragm is positioned in the cavity and configured to form a first and a second capacitance with the first wall and a third and a fourth capacitance with the second wall which change in response to the applied pressure. The capacitances form a first transfer function and a second transfer function. Changes in the first transfer function relative to the second transfer function are detected to provide a diagnostic output.

Abstract: A pressure transmitter with a fluid isolator that includes a sensor tube and a fill tube that have “D” shaped ends that connect together in a port internal to the transmitter. The shaped ends can be brazed into the port for sealing. Fitting both the sensor tube and the fill tube in the same port provides a low cost isolator with reduced isolator liquid volume. The fluid isolator has an isolator diaphragm with a central diaphragm region overlying a central backing plate that includes a annular groove. The annular groove avoids slow response of the isolator after an overpressure condition.