US Patent 7650798 Vented high-temperature piezoelectric-based field device

A process fluid sensor for sensing a characteristic of a process fluid is provided. The process fluid sensor includes a metallic sensor body that defines a chamber therein. A piezoelectric crystal element is disposed proximate the chamber and is configured to generate an electrical signal in response to a mechanical input. The piezoelectric crystal element is mechanically coupleable to the process fluid, but is sealed within the sensor body with the exception of a gaseous pathway. A vortex flowmeter utilizing the process fluid sensor is also provided.