Abstract: The present invention is a diaphragm seal for an instrument having a first coupling member with a cavity in communication with the instrument, a pressure-responsive diaphragm attached within the cavity of the first coupling member, an adapter ring fitted to the first coupling member, and a second coupling member connected to the first coupling member. The adapter ring is a rigid cylindrical member having an internal shoulder extending inwardly of the cylindrical member at the end opposite the diaphragm. The adapter ring has a sleeve fitted within the cylindrical member so as to overlie the internal shoulder. The second coupling member has an internal area communicating with the interior of the adapter ring. The adapter ring is interposed between the first and second coupling members. The second coupling member has a lining surrounding the internal area. This lining is in sealed relationship with the sleeve of the adapter ring. The lining and the sleeve are composed of a synthetic resin polymeric material.

Abstract: A fluid pressure-responsive diaphragm comprising a discal body and a holding ring. The holding ring is fastened to the discal body and has an outwardly turned lip formed at the inner edge of the holding ring. The holding ring has a different thickness than the thickness of the discal body. Both the discal body and the holding ring are made of metallic substances. The discal body has a plurality of annular corrugations in a radial periodic waveform configuration and a plurality of radially extending spokes in a circumferential periodic waveform conforming to and integrated with the peaks and valleys of the annular corrugations. The holding ring is fastened to and aligned with the periphery of the discal body and the outwardly turned lip is adjacent to the outermost annular corrugation. A compressible seal is juxtaposed within the area defined by the outwardly turned lip and a surface of the holding ring.