Dispensing pump with priming feature

A dispensing pump comprising:

• a pump cylinder, said pump cylinder comprising an inner wall;
• a pump piston reciprocally mounted in said pump cylinder, said pump piston comprising a plurality of seals sealing against said inner wall, said pump piston reciprocating in said pump cylinder from a first, axially outward, position to a second, axially inward, position;
• and
• a plurality of priming mechanisms on said pump cylinder inner wall, one of said priming mechanisms being located at each location of said seals on said inner wall at said second position of said pump piston, each said priming mechanism creating at least one gap between one of said seals and said inner wall, each said priming mechanism comprising at least one flat, said at least one flat having a surface defining a chord of said inner wall.

A method of venting air from a pump chamber comprising the steps of:

• providing a cylinder wherein said cylinder comprises an inner wall;
• providing a piston reciprocally mounted in said cylinder wherein said piston comprises at least one seal sealing against said inner wall and wherein said piston reciprocates in said cylinder from a first, axially outward, position to a second, axially inward, position;
• providing at least one priming mechanism on said cylinder inner wall, said step of providing at least one priming mechanism comprising the step of forming at least one flat on said inner wall wherein said at least one flat has a surface defining a chord of said inner wall;
• engaging said at least one seal with said at least one priming mechanism at said second position of said piston;
• creating at least one gap between said at least one seal and said inner wall wherein said at least one gap is sufficiently small so that air passes through said at least one gap but a liquid will not pass through said at least one gap;
• and
• exhausting air through said at least one gap.

A dispensing pump comprising:

• a cylinder, said cylinder comprising an inner wall;
• a piston reciprocally mounted in said cylinder, said piston comprising at least one seal sealing against said inner wall, said piston reciprocating in said cylinder from a first, axially outward, position to a second, axially inward, position;
• and
• at least one priming mechanism on said cylinder inner wall, said at least one priming mechanism being located at a location of said at least one seal on said inner wall at said second position of said piston, said at least one priming mechanism creating at least one gap between said at least one seal and said inner wall, said at least one priming mechanism comprising at least one flat, said at least one flat having a surface defining a chord of said inner wall.