Two position rotary reciprocating pump with liquid displacement flow

Abstract

A rotary reciprocating pumping apparatus is provided with a positive two position adjustment feature which allows the piston stroke to be increased to a maximum and repeatably, automatically, returned to a second calibrated dispensing position. Such rotary reciprocating pump is further provided with an adjustable liquid displacement velocity profile to maintain sufficient velocity of liquid flow at the end of the pump discharge cycle to enable injection of small volumes of liquid through a pump exhaust port, thereby eliminating the inaccurate and time consuming operation of touching off a small volume of liquid as a drop characterizing known rotary reciprocating pumping systems. A stabilizing ring of the cylindrical pump case is flush mounted within a counterbore of a pump mounting plate with one side of the ring directly abutting the bottom of the counterbore and a diametrically opposite side and abutting one or more standoffs to set the axis of the pump case and the pumping chamber at a slight angle in a transverse plane to the axis of the counterbore within the pump mounting plate, thereby modifying the pump piston liquid velocity profile to ensure significant fluid velocity at termination of the pump piston discharge stroke.