Patent attributes
A process control instrument for coupling to a process is attachable to a metal flange. The flange has a first passageway adapted to be filled with process fluid. The process control instrument includes a body having an opening adjacent to the first passageway for receiving process fluid from the first passageway when the process control instrument is attached to the flange. A diaphragm is disposed across the opening for fluid communication with the process fluid. A seal is positionable against the flange to prevent process fluid from leaking past the flange and diaphragm. The seal includes a ring positioned in the opening and coupled to the body, the ring being substantially in contact with the diaphragm along an inner annular shoulder when the body is not attached to the flange (unloaded).