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A reciprocating pump for dispensing liquids from a container comprises a hollow body in which is slidably fitted a hollow piston. A piston seat is located in the body and provides a segment sized for sealing fit inside the hollow piston, thereby minimizing possible leakage through the pump when it i

A reciprocating pump for dispensing liquids from a container comprises a hollow body in which is slidably fitted a hollow piston. A piston seat is located in the body and provides a segment sized for sealing fit inside the hollow piston, thereby minimizing possible leakage through the pump when it is transported with a liquid filled container. Upper and lower valves are provided in the piston and body respectively. The piston seat is adapted to interact with the upper valve member to hold it open during a portion of an upward stroke of the piston thereby drawing any undispensed liquid back into the pump.

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A pump for dispensing liquids from a container, comprising: a hollow body having upper and lower ends having openings therein; a hollow piston slidable reciprocally with sealing fit in said body, said piston having upper and lower ends having openings therein; a piston seat sized to be received insi

A pump for dispensing liquids from a container, comprising: a hollow body having upper and lower ends having openings therein; a hollow piston slidable reciprocally with sealing fit in said body, said piston having upper and lower ends having openings therein; a piston seat sized to be received inside said piston, said piston seat having a larger diameter segment at its lower end sized for sealing fit inside said piston when said piston is at the terminal portion of a downward stroke and the initial portion of an upward stroke of said piston, and a smaller diameter segment at its upper end sized to provide a space between said smaller diameter segment and the inner walls of said piston; a chamber defined by said piston, body and piston seat; means for biasing said piston against a downward stroke and for biasing said piston with an upward stroke; an upper valve positioned in the upper end of said piston, said upper valve being moveable to open said opening in said upper end of said piston during a downward stroke of said piston to dispense liquids from said chamber; and a lower valve positioned in the lower end of said body, said lower valve being moveable to open said opening in said lower end of said body during an upward stroke of said piston to permit liquid to enter said chamber; a dispensing nozzle located at the upper end of said piston, said upper valve being located between said dispensing nozzle and said chamber; cooperating means on said upper valve member and the upper end of said piston seat to hold said upper valve open during an initial portion of an upward stroke of said piston, whereby a pressure gradient between said nozzle and said chamber is created to cause liquid being dispensed from said pump to be drawn towards said chamber from said nozzle.