Abstract: A fluid flow control valve for use with chemical fluids where avoidance of contaminants is important, is provided. The valve has a flow control chamber divided into an analytical section and a driver section by a metallic foil membrane operating member, clamped between the peripheral rim of the chamber and the upper wall. The foil membrane is movable in response to driver fluid pressure between open and closed positions. The upper portion of the rim which engages the membrane is of relatively small surface area, and is made of a softer material than that from which the membrane and the upper wall are constructed, .about. thereby providing a very effective means of sealing the membrane periphery to the upper wall when tightly clamped. The membrane is of domed shape, and is formed in situ by deformation of a planar metal foil sealingly clamped in position within the chamber, by application of fluid pressure thereto through a port to the chamber.

Abstract: A fluid flow control valve for use with chemical fluids where avoidance of contaminants is important, is provided. The valve has a flow control chamber divided into an analytical section and a driver section by a metallic foil membrane operating member, clamped between the peripheral rim of the chamber and the upper wall. The foil membrane is moveable in response to driver fluid pressure between open and closed positions. The upper portion of the rim which engages the membrane is of relatively small surface area, and is made of a softer material than that from which the membrane and the upper wall are constructed, thereby providing a very effective means of sealing the membrane periphery to the upper wall when tightly clamped. The membrane is of domed shape, and is formed in situ by deformation of a planar metal foil sealingly clamped in position within the chamber, by application of fluid pressure thereto through a port to the chamber.