A valve assembly for a fluid pump includes a valve body; a fluid inlet and a fluid outlet defined in the valve body; a valve seat; and an inlet disk disposed in the valve body having an inner portion, an outer portion fixed within the valve body, and a plurality of legs connected between the inner portion and the outer portion so that the inner portion is movable between a first position against the valve seat and a second position spaced apart from the valve seat. The connection between the legs, the inner portion and the outer portion provides a spring bias force to the inner portion against movement of the inner portion from the first position. The plurality of legs, the inner portion and the outer portion are configured such that the spring bias force is asymmetric as applied to the inner portion of the inlet disk.