Importance

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Abstract

A diaphragm valve is provided with a removable metallic elastic seating ring (7) having a first passage (10) and at least one second passage (11) extending through it. The first passage communicates with an inlet passage (8) of the valve while the second passage communicates with the outflow passage (9). A first surface (7a) of the seating ring is provided with a valve seat (12) against which the diaphragm (6) may be pressed to block fluid flow through the valve. A second surface (7b) of the seating ring has two annular and axially extending projections (15, 16). The first projection (15) contacts a bottom surface (2a) of valve chamber (2) in a region surrounding the opening where the inflow passage joins the valve chamber. The second projection (16) contacts the bottom surface of the valve chamber around the periphery of the valve chamber. The first projection extends axially of the seating ring to a slightly greater extent than the second projection so that when a diaphragm holder ( 5) presses the diaphragm against the periphery of the seating ring, the seating ring flexes thus causing increased contact pressure between the first projection and the bottom surface of the valve chamber. This reduces the possibility of leakage flow between the bottom wall and the seating ring from the inflow passage to the outflow passage.

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First Claim