| 摘要 |
A pump dispenser (101) connected to a container (107) of liquid has a first piston (3) reciprocatable in a first cylinder (5) for pumping a quantity of liquid at each depression of the piston. A valve member (8) received within a channel in the first piston is spring biassed into a position in which a dispensing outlet (19) is normally closed and is movable to release liquid in response to excess liquid pressure in the first chamber. A cylindrical extension (11) to the valve member defines a conduit (60) communicating with liquid in the container and is separable from the valve member to open a liquid inlet port (105) for recharging the first chamber. A second piston (39) is movable in tandem with the first piston and cooperates with a second cylinder (41) to provide suction on a return stroke of the pistons which is utilised to remove residual liquid from a dispensing channel (7) delivering pumped liquid to a nozzle (32). Residual liquid collected in the second chamber is returned to the container during the next subsequent actuating stroke of the pistons. The dispenser is particularly useful for water-borne liquid products because its self-cleaning action prevents clogging.
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