Patent ID: 7717303

Claim:
A pump for manually dispensing quantities of a fluid substance sealedly contained in a container, comprising: a cup-shaped body having an open end, a closed end including a first hole, and an inner surface; a ring cap sealed on the open end of the cup-shaped body, said ring cap including a second hole and including no other holes or apertures; a hollow operating stem for dispensing the fluid substance contained in the container, the stem including an outer surface, and the stem extending from and being axially translatable through the second hole provided in said ring cap; an annular piston sealedly translatable both along the inner surface of the cup-shaped body and along the outer surface of the stem, said piston having upper and lower surfaces; and a unidirectional valve, wherein the fluid substance can, via the unidirectional valve, enter through the first hole into a lower pump chamber in the cup-shaped body from which the substance can be expelled by being dispensed outside of the pump, wherein said lower pump chamber is bounded by the annular piston, wherein said stem with said piston defines an upper pump chamber in said cup-shaped body, wherein the outer surface of the stem forms a seal against an opposing surface of the second hole in the ring cap and maintains the seal throughout translation of the stem, and wherein in the cup-shaped body there is provided at least one passageway which connects said upper chamber to the container outside of said cup-shaped body.