A valve unit for regulating the flow of working fluid between a working chamber of a fluid working machine and both a first working fluid line and second working fluid line, the valve unit comprising: a first valve comprising a first valve member and one or more cooperating first valve seats, a second valve comprising a second valve member and one or more cooperating second valve seats, an actuator coupled to both the first and second valve members through which a force may be applied to urge the first valve member open or closed and to urge the second valve member open or closed, a coupling between the actuator and the first valve member, wherein the coupling between the actuator and the first valve member comprises a connector which extends at least partially through the second valve member.

A pump adapted for use in desalination systems that has four cylinders, with a double acting piston in each cylinder. Each cylinder and piston thereby defines a feed chamber and a recovery chamber. The pistons are connected to a common drive. The connection to the common drive is such that the pistons reciprocate in a sequence equally spaced in time. Reciprocating valving for each piston is driven by the common drive to be 90 degrees out of phase with the respective piston. The valving connects the recovery chamber alternately to an inlet manifold for an intake stroke of the piston relative to the recovery chamber, and to an outlet manifold for a discharge stroke of the piston relative to the recovery chamber. There is a brief period of closure coinciding with top dead centre and bottom dead centre of the piston, during which the recovery chamber is blocked off from both the inlet and outlet manifolds. The reciprocating valving is midway between its top dead centre and bottom dead centre during the period of closure.

A pulsation-free wet spraying machine resolves the issue of pulsing during pumping of a concrete spraying machine The wet spraying machine includes a frame, a pumping mechanism, a swing mechanism and a hydraulic system, wherein the pumping mechanism includes a hopper, a material chamber, a concrete feeding mechanism, an auxiliary feeding mechanism and a distribution valve. The hopper of the pumping mechanism is disposed above the material chamber. The distribution valve is disposed inside the material chamber, the concrete feeding mechanism and the auxiliary feeding mechanism both include a hydraulic cylinder, a concrete piston and a concrete cylinder, a discharge pipe is a three-way pipe fixed at a side surface of the material chamber, an auxiliary discharge pipe of the discharge pipe is connected with an auxiliary concrete cylinder, and a through hole is disposed on the auxiliary concrete cylinder. The swing mechanism includes a swing hydraulic cylinder, a swing arm and a swing hydraulic cylinder base, an auxiliary piston rod of the auxiliary feeding mechanism passes through a mandrel to push an auxiliary concrete piston to move inside the auxiliary concrete cylinder. In addition, the pulsation-free wet spraying machine stably feeds a material, has a compact structure, and is wear-resistant.

A pump adapted for use in desalination systems that has four cylinders, with a double acting piston in each cylinder. Each cylinder and piston thereby defines a feed chamber and a recovery chamber. The pistons are connected to a common drive. The connection to the common drive is such that the pistons reciprocate in a sequence equally spaced in time. Reciprocating valving for each piston is driven by the common drive to be 90 degrees out of phase with the respective piston.

The valving connects the recovery chamber alternately to an inlet manifold for an intake stroke of the piston relative to the recovery chamber, and to an outlet manifold for a discharge stroke of the piston relative to the recovery chamber. There is a brief period of closure coinciding with top dead centre and bottom dead centre of the piston, during which the recovery chamber is blocked off from both the inlet and outlet manifolds. The reciprocating valving is midway between its top dead centre and bottom dead centre during the period of closure.

A pump in desalination systems has four cylinders, each having a double acting piston. Each cylinder and piston defines a feed chamber and a recovery chamber. The pistons connect to a common drive. The connection to the common drive is such that the pistons reciprocate in a sequence equally spaced in time. Reciprocating valving for each piston is driven by the common drive to be 90 degrees out of phase with the respective piston. The valving connects the recovery chamber alternately to an inlet manifold for an intake stroke of the piston relative to the recovery chamber, and to an outlet manifold for a discharge stroke of the piston relative to the recovery chamber. A brief period of closure coincides with top dead centre and bottom dead centre of the piston, during which the recovery chamber is blocked off from both the inlet and outlet manifolds. The reciprocating valving is midway between its top dead centre and bottom dead centre during the period of closure.

A liquid pump including a pump housing having an interior sidewall forming an interior. The housing has an inlet port and an outlet port. A liner is disposed in the interior and has opposed transverse openings in line with the inlet and outlet ports. The liner has a central longitudinally extending bore. A pump piston is axially and rotatably slidable within the liner longitudinal bore for pumping the liquid from the inlet port to the outlet port. A seal assembly is secured to the pump housing adjacent to an upper end of the liner. The seal assembly including a seal body, an upper end of the piston extending though the cap and in sealing engagement with the seal body, the seal assembly and liner upper end forming a cavity there between. An upper end of the piston extending though the seal assembly and in sealing engagement with the seal body, the seal body and liner upper end forming a cavity there between. The housing having a passageway providing a fluid communication between the cavity and the inlet port.

A pump in desalination systems has four cylinders, each having a double acting piston. Each cylinder and piston defines a feed chamber and a recovery chamber. The pistons connect to a common drive. The connection to the common drive is such that the pistons reciprocate in a sequence equally spaced in time. Reciprocating valving for each piston is driven by the common drive to be 90 degrees out of phase with the respective piston. The valving connects the recovery chamber alternately to an inlet manifold for an intake stroke of the piston relative to the recovery chamber, and to an outlet manifold for a discharge stroke of the piston relative to the recovery chamber. A brief period of closure coincides with top dead centre and bottom dead centre of the piston, during which the recovery chamber is blocked off from both the inlet and outlet manifolds. The reciprocating valving is midway between its top dead centre and bottom dead centre during the period of closure.