Abstract: A transmitter provides an output that is indicative of pressure and has two modular transmitter bodies, one including a sensor, and the other having an isolator diaphragm with a substantially non-compressible fluid that transfers movement of the isolator diaphragm to the sensor. The bodies each have mating passageways to transfer non-compressible fluid from one body to the other and are assembled together using a ring of extrusile material disposed around the mating portions of the passageways to seal the passageways together when the transmitter bodies are assembled. The isolation fluid is filled in the passageway of the bodies before the first and second transmitter bodies are assembled. The assembly can be accomplished without complex procedures and still insure that accurate transmitter operation will be obtained.

Abstract: An isolator apparatus for coupling pressure from a pressurized fluid carried in a conduit to a pressure sensor in a pressure transmitter having an isolation diaphragm, isolation fluid, and a pressure sealing ring for providing an annular seal around an active region of the isolation diaphragm. The isolator apparatus includes a rigid support for spacing the pressure sealing ring away from the active region which reduces pressure measurement errors related to temperature-induced isolation fluid expansion, such that the annular seal overhangs the isolation diaphragm's active region.

Abstract: A pressure transmitter is coupled directly to an industry standard flange adapter union having a standard bolt hole spacing. Small diameter isolator diaphragms are positioned on the transmitter housing at locations so that the industry standard flange adapter union which couple fluid pressure sources to act on the isolator diaphragms without an intermediate large flange or manifold as is presently required and using the fasteners for the adapter union to complete the coupling. The smaller isolaters fit within the bolt hole spacing of the industry standard adapter union.