ring seal 66 encircles a fluid flow path formed by suction port 48 and suction ring seal 68 and backup ring 67 around valve seat 54 seal between the valve seat and the wall of the chamber 52 as illustrated in fig2 valve seat 54 includes a circular tapered seating surface 54a and valve member 60 includes a circular tapered seating surface 60a adapted to engage surface 54a in a sealing relationship as shown in fig2 in accordance with the teachings of u s pat no 3 986 523 assigned to the assignee of this invention it is preferred that these sealing surfaces and those on the discharge valve to be described be maintained as small as possible for the pressures employed to issue proper seating and reduce the forces required to move the valve members to and from their sealing positions suction valve member 60 is shown in fig3 removed from its valve seat 54 also seen in fig3 is a suction valve guide 70 which as seen in fig2 fits between valve seat 54 and the end of chamber 52 that is adjacent passage 50 both the valve 60 and guide 70 are symmetrically located with respect to the cylindrical axis of the inner surface 58 of valve seat 54 valve 60 has.