A ring valve assembly for use in a reciprocating type fluid pump with a piston cylinder and a cylinder head is disclosed. The valve assembly includes a ring valve having a fluid seal surface for a selectively closing a fluid passage of a cylinder head and bias means for the ring valve for urging the ring valve in a first direction. The bias means includes the outer peripheral edge region of the ring valve being secured between opposing upper and lower annular surfaces with a predetermined smaller clearance. The upper annular surface includes an outer edge and the lower annular surface includes an inner edge which defines a fulcrum radially inward of the outer edge. The ring valve undergoes first and second stages of deflection during operation, wherein the ring valve is vertically displaced a distance equal to the predetermined small clearance against only one of the upper or lower annular surfaces in the first stage of deflection and the ring valve pivots about the inner edge and deforms into the shape of a cone about the fulcrum in the second stage of deflection. A third stage of deflection is also provided in which the ring valve is restrained between the inner edge and outer edge of the lower and upper annular surfaces, respectively, thereby increasing the stiffness of the intake valve in the third stage of deflection.