DISPENSER PUMPS

摘要

A fixed-nozzle dispenser pump suitable for large doses has a downwardly-directed nozzle tip (32) and an outlet valve arrangement (4) in the nozzle (3). A blocking element e.g. ball (41) of the outlet valve (4) is biased back along a close-fitting tubular draw path (43) in the valve after dispensing, so as to draw product back out of the nozzle tip and prevent dripping. A further feature is subdivision of the nozzle tip and a flexible flap valve (35) blocking a resulting passage segment in the nozzle. This facilitates clearance of another nozzle passage (36) by the suck-back. A further feature is a membrane (24) across the front of the piston plunger, advanceable relative to the piston seal (231) by pressure on the plunger head (21). This helps accommodation of sucked-back fluid and enables a spot-dosing action.