Abstract: Disclosed is a valve for fluids, gases or liquids, in which the closure member of the valve is supported, when in closed position, in such fashion that pressure on the intermediate or central portion of the closure causes the periphery of the closure to move upstream, into contact with seats or seals carried by the valve body. Specifically, the plate, when closed, is forced by the pressure of the fluid being controlled against fulcrum members, these fulcrum members being located closer to the periphery of the closure member than to its center, whereby the net effect of pressure on the plate as a whole is effective to deflect the central portion of the plate downstream while deflecting the peripheral portions of the plate upstream into sealing, seating engagement with the seals or seats carried by the valve body.