A pump assembly for dispensing a foamable liquid, comprising:
- a foam pump, the foam pump comprising:
- a. a dual air and liquid cylinder including:
- i. a base wall having a central opening therein defining a liquid inlet;
- ii. an inner annular wall extending from said base wall and surrounding the central opening and having an open end opposite the base wall;
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- iii. an outer annular wall extending from said base wall and surrounding the inner annular wall and having an open end opposite the base wall;
- b. a dual air and liquid piston assembly received in said dual air and liquid cylinder, said dual air and liquid piston assembly including:
- i. an air piston member including an air piston ring slidably engaging an inner surface of said outer annular wall, the air piston member cooperating with the outer annular wall to define a collapsible air chamber for receiving air;
- ii. a liquid piston including a liquid piston ring supported on a liquid piston shaft, the liquid piston ring slidably engaging an inner surface of the inner annular wall, the liquid piston cooperating with the inner annular wall to define a collapsible liquid chamber for receiving the foamable liquid, wherein the dual air and liquid piston assembly is movable in relation to the dual air and liquid cylinder along a flow axis;
- iii. the liquid piston shaft having a first end axially adjacent the collapsible liquid chamber, a second end defining a liquid outlet, and a central passageway extending between the first end and the second end, the second end of the liquid piston shaft attached to the air piston member to move therewith;
- c. a liquid inlet valve member received within the central opening for regulating flow through the liquid inlet;
- d. a liquid outlet valve member disposed at the second end of the liquid piston shaft for regulating flow through the liquid outlet;
- e. the dual air and liquid piston assembly including a mixing chamber downstream of the liquid outlet, the mixing chamber in fluid communication with the collapsible liquid chamber through the liquid outlet valve member;
- f. the mixing chamber in fluid communication with the collapsible air chamber through a plurality of air passageways wherein each of the air passageways is configured to cause air entering the mixing chamber to rotate around the flow axis;
- g. a biasing member urging said dual air and liquid piston assembly to a non-actuated position, wherein the foam pump is actuatable by urging said dual air and liquid piston assembly against said biasing member to an actuated position in which said collapsible air chamber and said collapsible liquid chamber are reduced in volume such that air is expelled from said collapsible air chamber and through said plurality of air passageways into the mixing chamber while at the same time foamable liquid is expelled from the collapsible liquid chamber through said central passageway with simultaneous movement of the air and the foamable liquid into the mixing chamber causing a turbulent mixing thereof in the mixing chamber;
- h. the liquid outlet valve member having a foot portion comprising an annular sealing ring peripherally bounding a perforated flange portion;
- i. the sealing ring seated on a plurality of ribs projecting into a counterbore formed within the air piston member;
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- j. each rib disposed in between adjacent air passageways of said plurality of air passageways;
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- a container containing the foamable liquid, the container having an opening in fluid communication with the liquid inlet.