Fischer & Porter Company

John J Bonner

Masahiro Kazahaya

C William Clayton

A capacitive pressure transducer constituted by a pressure sensor whose capacitance is caused to vary as a function of an applied pressure and a coupling assembly adapted to hydraulically convey the variable pressure of the fluid to be metered to the pressure sensor while isolating the structure of the sensor from the fluid. The sensor is formed by a cylinder, one end of which is enclosed by a deformable diaphragm that serves as one plate of a capacitor, deformation of the diaphragm in response to pressure acting to vary the dielectric spacing between the diaphragm plate and a second plate to produce a corresponding change in the value of the capacitance. The coupling assembly includes a body component having a column section and a base section, the column section being received within the cylinder of the sensor with its head spaced from the diaphragm to define therewith a sensor chamber which communicates through a passage in the column section with an isolation chamber formed at the bottom of the base section and sealed by a barrier diaphragm. The chambers and the passage are filled with hydraulic fluid whereby pressure applied to the barrier diaphragm by the fluid to be metered is transmitted to the sensor diaphragm.

Capacitive pressure transducer

A pressure transmitter for sensing fluidic pressure to produce an indication that is converted into a signal for transmission to a remote station. The transmitter includes a sensor constituted by a diaphragm which seals a chamber in a meter body subject to fluid pressure, the diaphragm being axially dilated in accordance with the applied pressure. Anchored on the diaphragm is an upstanding force beam which is pushed thereby in the axial direction. A range spring which is offset with respect to the axis of the beam is connected between an intermediate point on the beam and the meter body. The spring acts to constrain axial motion of the beam, whereby when the diaphragm is dilated by fluidic pressure, the beam is caused to deflect to an extent determined thereby. A motion detector is operatively coupled to the upper end of the beam to convert the deflection thereof into a corresponding signal for transmission.

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Philadelphia, PA, United States of America

John J Bonner