Low residual inverted pumps, dispensers and refill units

摘要

A foam pump (120) including a housing (250) and a piston (220) that reciprocates within the housing is disclosed herein. The piston has a hollow portion (232) and an orifice (230) through the wall of the piston. A first seal (228) located proximate the upper end of the piston provides a seal between the piston and the housing. A liquid inlet (280) is located in the side wall of the housing at a point lower than the top of the piston. A one-way liquid inlet valve (282) is located proximate the liquid inlet and a one-way liquid outlet valve (234) is located prior to the liquid outlet (242). A charge chamber (270) is defined at least in part by the liquid inlet valve, the liquid outlet valve, a wall of the piston and a wall of the housing.