Patent attributes
A dispensing system includes a pump mechanism that has a liquid chamber, a liquid piston for delivering fluid to a mixing chamber, and a valve component biased to close the outlet from the liquid chamber. The pump mechanism also has an air chamber, and an air piston for delivering air to the mixing chamber. A bore allows passage of a mixture of the air and the liquid from the mixing chamber to a dispensing tube. A pump actuator moves the air piston and the liquid piston to propel a dose of the mixture of the air and the liquid through the bore and into the dispensing tube and to collapse a draw-back chamber. The draw-back chamber expands to draw the mixture of the air and the liquid from the dispensing tube into the draw-back chamber. The valve component is biased to close the first outlet before the draw-back chamber expands.
