Importance

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Abstract

A pump dispenser connected to a container of liquid has a first piston reciprocatable in a first cylinder for pumping a quantity of liquid at each depression of the piston. A valve member received within a channel in the first piston is spring biassed into a position in which a dispensing outlet is normally closed and is movable to release liquid in response to excess liquid pressure in the first chamber. A cylindrical extension to the valve member defines a conduit communicating with liquid in the container and is separable from the valve member to open a liquid inlet port for recharging the first chamber. A second piston is movable in tandem with the first piston and cooperates with a second cylinder to provide suction on a return stroke of the pistons which is utilised to remove residual liquid from a dispensing channel delivering pumped liquid to a nozzle. Residual liquid collected in the second chamber is returned to the container during the next subsequent actuating stroke of the pistons. An actuator mounted on the first piston communicates lost motion to the second piston and provides valve action for applying suction to the dispensing channel. The dispenser is particularly useful for water borne liquid products because its self cleaning action prevents clogging.

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First Claim