Self-priming passive dosing dispenser

Claim 1

A passive dosing dispenser comprising an internal reservoir for containing a quantity of a solution, and means for causing a predetermined dose-volume of a liquid to be conducted into said reservoir so that a dose-volume of said solution is displaced from said reservoir and caused to issue from said dispenser in response to the level of a body of said liquid being lowered from a first elevation to a second elevation, said means comprising a dose-volume measuring cavity, an inlet conduit, and a discharge standpipe, said inlet conduit having a top end in fluid communication with the interior upper reaches of said reservoir and a bottom end in fluid communication with the bottom portion of said measuring cavity, said standpipe having an upper end in fluid communication with the interior upper reaches of said reservoir and an open lower end, said reservoir being in fluid communication exclusively with said inlet conduit and said standpipe, said reservoir being adapted to hold a quantity of a solid-state product which is solvable in said liquid and for being flooded with said liquid to form said solution in said reservoir by dissolving some of said product, said dispenser further comprising means for being so disposed in said body of liquid that said measuring cavity is filled with said liquid whenever the level of said body of liquid is raised to said first elevation from said second elevation and so that said dose-volume of said liquid will be vacuum-transferred from said measuring cavity via said inlet conduit to said reservoir and said dose-volume of said solution will be displaced from said reservoir into said standpipe and thence from said dispenser whenever the level of said body of liquid is lowered to said second elevation, said measuring cavity including means for making said dispenser self-priming, said means comprising a first inlet port pervious to the passage of liquid located at a sufficiently high elevation with respect to the upper end of said standpipe that said reservoir is filled by liquid entering through said standpipe when said dispenser is initially immersed in said body of liquid, said means also including a second inlet port in said measuring cavity having means for making said second inlet port impervious to the passage of liquid for a period of time sufficient for said reservoir to be filled by liquid entering through said standpipe upon immersion of said dispenser in said body of liquid, said means for making said second inlet port impervious to the passage of liquid being soluble upon sustained immersion in said liquid, said second inlet port being located at a sufficiently low elevation with respect to the upper end of said standpipe that said measuring cavity is filled through said second inlet port before the level of said body of liquid reaches the upper end of said standpipe whenever the level of said body of liquid rises from said second elevation to said first elevation.