Vacuum actuated pressurized fluid dispenser

A pressurized fluid dispenser comprising an inner axially collapsible container gravity fillable with said fluid to be dispensed, an outer surrounding container defining an annular space between the inner and outer containers capable of being evacuated, means on said dispenser to permit evacuation of the space between the inner and outer containers, piston means for imposing pressure on said inner container to expel its contents, said piston means acting within said outer container and sealably attached therewith and being movable coaxially or paraxially of said inner container, said piston means having one surface exposed to the atmosphere and an opposite surface exposed to said evacuatable space and against said inner container valve means for controlling the egress of the contents of said inner axially collapsible container, said inner axially collapsible container having a projected area perpendicular to its axis sufficiently less than the projected area of said piston means perpendicular to the axis of said inner axially collapsible container that the action of the atmosphere on said piston means when said annular space is evacuated presses said piston means against said inner axially collapsible container to controllably expel the contents of said axially collapsible inner container through said valve means without the necessity of pressurized filling of said inner, axially collapsible container.