Seal for process pressure to current transmitter

Claim 2

A fluid-tight seal for connecting a body portion of a pressure transmitter to an associated diaphragm backup plate that has a different thermal coefficient of expansion than said body portion, comprising a free-standing ring integral with and extending from the body portion and positioned in a surrounding spaced relationship with said backup plate, and a welded joint extending between a surface at the free end of said ring and an adjacent surface of said backup plate, said free end of said ring being deflectable radially in a cantilever fashion upon said body portion by a force applied through said welded joint from said backup plate upon a change in ambient temperature.

Claim 3

A fluid-tight seal as set forth in claim 1 wherein said backup plate is of a substantially disc-shaped configuration.

Claim 4

A fluid-tight seal as set forth in claim 2 wherein said welded joint is located between an outer periphery of said backup plate and said ring.

Claim 5

A fluid-tight seal as set forth in claim 1 wherein said backup plate is spaced from said ring by a space having a tapered cross-section progressively increasing from the welded joint.

Claim 6

A fluid-tight seal as set forth in claim 4 wherein said backup plate has a frusto-conical cross-section with a center of revolution concentric with a center of said ring and said ring has a straight inside surface surrounding said backup plate.

Claim 7

A fluid-tight seal as set forth in claim 3 wherein said ring has an annular recess in its free end for mating with the adjacent surface of said backup plate to provide a location for said welded joint.

Claim 8

A fluid-tight seal as set forth in claim 1 wherein said backup plate has a lower coefficient of thermal expansion than said ring.

Claim 9

A fluid-tight seal as set forth in claim 1 wherein said backup plate has a higher coefficient of thermal expansion than said ring.

Claim 10

A pressure to current transmitter comprising a hollow process fluid inlet portion having an inlet end and an open end, a hollow body portion having an open end facing said open end of said inlet portion, a diaphragm, a backup plate supporting said diaphragm, across said open end of said inlet portion, a free-standing ring integral with and extending from said body portion as an extension of said open end and positioned in a surrounding spaced relationship with said backup plate, a welded joint extending between a surface at a free end of said ring and an adjacent surface of said backup plate, said free end of said ring being deflectable radially in a cantilever fashion upon said body portion by a force applied through said welded joint from said backup plate upon a change in ambient temperature, fluid passage means in said backup plate to provide a fluid passage from said open end of said body portion to a volume enclosed by said diaphragm and said backup plate and sensor means located in said body portion and arranged to detect changes in pressure of a fluid in said body portion communicating with said diaphragm in said volume by way of said fluid passage means.

Claim 11

A pressure to current transmitter comprising a hollow process fluid inlet portion having an inlet end and an open end, a hollow body portion having an open end facing said open end of said inlet portion, a diaphragm, a backup plate supporting said diaphragm, across said open end of said inlet portion, a free-standing ring integral with and extending from said body portion as an extension of said open end and positioned in a surrounding spaced relationship with said backup plate, a welded joint extending between a surface at a free end of said ring and an adjacent surface of said backup plate, said free end of said ring being deflectable radially in a cantilever fashion upon said body portion by a force applied through said welded joint from said backup plate upon a change in ambient temperature, fluid passage means in said backup plate to provide a fluid passage from said open end of said body portion to a volume enclosed by said diaphragm and said backup plate and sensor means located in said body portion and arranged to detect changes in pressure of a fluid in said body portion communicating with said diaphragm in said volume by way of said fluid passage means.

Claim 12

A pressure to current transmitter as set forth in claim 9 wherein said backup is of a substantially disc-shaped configuration and said welded joint is located between an outer periphery of said backup plate and said ring.