Rosemount Inc.

Steven M Lemire

Gerald R Cucci

Bennett L Louwagie

Craig A Everett

An isolator diaphragm is formed and connected to a support member so it will withstand periodic high pressure cleaning. Such periodic cleaning includes use of heated, concentrated cleaning solutions flowing under high pressure from a nozzle which moves rapidly over segments of an exposed surface of the isolator diaphragm. The present invention prevents isolator diaphragm failure precipitated by the substantially incompressible isolator fluid driven toward the perimeter of the diaphragm during cleaning operations. Such cleaning operations generate a separating force between the isolator diaphragm and diaphragm support. The isolator diaphragm has a peripheral wall portion bonded to a planar support surface and is formed to have an offset center region. The peripheral wall and center region are joined by a conical, inclined wall bounding the center portion. The support member has a correspondingly shaped recess with an inclined annular wall that supports the conical wall of the diaphragm. The primary diaphragm flexure point of the center portion of the diaphragm is moved away from the perimeter of the diaphragm, to adjacent the junction of the inclined wall and the center region. The bonding area is not subjected to a high separating force due to the movement in the incompressible fill fluid to a localized region of the diaphragm adjacent a seal or junction line.

Pressure isolator assembly for sanitary processing

An isolator for use in pressure transmitters for isolating the process fluid being sensed from a sensor, comprises an isolating diaphragm that is thin, and made of a suitable corrosion resistant metal, such as tantalum, and which must be anchored to an isolator housing made of a substantially different metal such as stainless steel. Tantalum is very resistant to corrosion, and is a high melting point metal, which is substantially higher than the material comprising the sensor housing so direct welding is virtually impossible. The present invention relates to securing a support ring of the same metal as the diaphragm surrounding the cavity formed for the isolator fluid, preforming a thin metal diaphragm made of the selected material, and then welding the diaphragm and a ring overlying the diaphragm directly to the support ring. Using a support ring that is separately secured in place on the isolator body permits the welding temperature to be raised sufficiently for fastening the high melting point components (tantalum) together without damaging the sensor housing.

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Chaska, MN, United States of America

Steven M Lemire