Abstract: The present invention provides systems and methods of dispensing liquids. In one embodiment, the system includes a pump with a removable pump module with at least one displacement piston and at least one piston valve. A motor and base assembly provide the supporting components of the pump which can be used in environments where precise small volumes of ultra-pure liquids must be transferred from a reservoir to a point of use. The preferred embodiment of the system prevents contaminants and air bubbles from being introduced into the liquid to be dispensed by placing a filter across the discharge line downstream from the pump, and providing a separate drawback line for performing the drawback of the liquid in the dispensing nozzle.

Abstract: The present invention provides systems and methods of dispensing liquids. In one embodiment, the system includes a pump with a removable pump module with at least one displacement piston and at least one piston valve. A motor and base assembly provides the supporting components of the pump, which can be used in environments where precise small volumes of ultra-pure liquids must be transferred from a reservoir to a point of use. The preferred embodiment of the system prevents contaminants and air bubbles from being introduced into the liquid to be dispensed by placing a filter across the discharge line downstream from the pump, and providing a separate drawback line for performing the drawback of the liquid in the dispensing nozzle.

Abstract: A rotary/reciprocating liquid dispensing pump for dispensing liquids in the nanoliter range has a narrow radial slot extending longitudinally from an end of a reciprocating, rotating cylindrical piston sliding in a smooth cylindrical bore of a pump housing at a closed end thereof, which slot extends outwardly to the periphery of the piston. The piston is selectively positioned in alignment with one of a plurality of circumferentially spaced small diameter radial passages within the housing opening directly to the cylindrical bore in the path of rotation of said slot. The ports thereof opening to the cylindrical bore are spaced circumferentially a distance in excess of the width of the slot. A linear liquid dispensing pump apparatus including such pump includes a stepping motor and an electromagnetic clutch/braking mechanism concentrically surrounding a lead screw, and the lead screw is threadably engaged with a stepping motor tubular rotor shaft.