Double-acting pump

Claim 1

A double-acting pump comprising: a metering cylinder, a piston in the metering cylinder, a pushrod attached to the piston, a first end cap removably fitted at one end of the metering cylinder, said first end cap containing an annular seal which supports the pushrod for reciprocal movement therein, a second end cap removably fitted at the other end of the cylinder, a pair of valve housings fitted to each one of said end caps, each valve housing in said pair defining either an inlet or an outlet port to said cylinder, a non-return valve located in each valve housing, each valve being supported in its housing between an annular seating and an annular stop, said seating and said stop communicating directly with the respective port and manifold whereby material, moved by said piston, is caused to flow past said valve, the external surface of the valve between portions engaging said seating and said stop being fluted so as to enable passage of material past said fluted surface while slidably engaging the internal wall of the valve housing, an outlet manifold removably fitted to the valve housings which define the outlet ports, an inlet manifold removably fitted to the valve housings which define the inlet ports, each of said manifolds comprising a sleeve, a tubular bend and a tubular tee, said tubular bend and said tubular tee of said manifolds being removably connected to the respective housings, a first backing plate clamped adjacent said first end cap, a draw plate adjacent said second end cap, at least two tie rods connected between said first backing plate and said draw plate, a second backing plate adjacent said first backing plate, said second backing plate being provided for connection to fixed supporting means for said pump, means connected to said draw plate for exerting a force on said second end cap whereby said end caps are drawn together, and a locking collar adjacent said second backing plate and threadably engaging said first backing plate, said collar being movable on said threaded engagement either to exert a clamping force on said first and second backing plates to hold said pump fast, or to release said clamping force whereby said pump can be bodily rotated about the axis of the metering cylinder without releasing the force securing the end caps and the metering cylinder in sealing relationship, the valve housing in each pair of said valve housings being located diametrically opposite the other valve housing across the diameter of said cylinder, whereby the attitude of the inlet and outlet valves in the valve housings can be changed by turning the pump bodily through 180° about said axis of the metering cylinder for draining said pump.