Piston operated fluid dispensing device capable of incrementally adjusting the volume being dispensed

摘要

A valve assembly includes a valve housing defining a metering chamber and an elongated stem. The stem is axially movable with respect to the valve housing for dispensing liquid and is rotatable for adjusting the length of the stroke of a piston to thereby select the volume of liquid dispensed with each actuation of the stem. A sliding float member is fitted around the stem within the chamber and is axially slidable with respect to the stem but is locked for rotation with the stem. The lower surface of the sliding float is locked for axial movement with the piston but is independently rotatable with respect to the piston. A pair of spaced poles extends parallel to the axis of the float and engages vaginations in a surface of the housing to thereby limit the length of the stroke of the piston. The poles of the float and the complementary pairs of vaginations in the housing are angularly spaced a distance of less than 180 degrees.