Combination valve vacuum breaker with co-acting valve in a liquid flow path

Claim 1

A liquid flow control device for controlling the pressurized flow of liquid in a single direction from a water main to a cistern containing a body of liquid open to the atmosphere and preventing back flow of the liquid when atmospheric pressure on the body of liquid exceeds the pressurized flow of liquid, said device including, in combination: a flow passage comprising a piece (4) having three interconnected, communicating branches, a first branch thereof (4b) comprising a pressurized-liquid outlet portion for directing the pressurized liquid into the body of water in the cistern, a second branch (4a) thereof cOmprising a pressure inlet portion for the liquid from the water main, and a third branch thereof open to the atmosphere and defining an atmospheric vent portion; a first collapsible valve sleeve of a flexible impermeable material freely depending from said first branch whereby the lower distal end of the flexible sleeve will be immersed in the body of water in the cistern and emmission of pressurized liquid into the body of liquid in the cistern is substantially silenced by the body of liquid, said first valve sleeve being secured at one end thereof in a fluid-tight manner about the end of said first branch, spaced from the third branch, such that said one end of said first valve sleeve is held open, whereby pressurized liquid flowing in a normal direction through said first branch defining said outlet portion enters said first valve sleeve at said open end thereof and distends the remainder of said sleeve to cause pressurized liquid to enter the body of liquid in the cistern, with reversal of the direction of liquid effecting a collapse of the first valve sleeve and an interruption of said flow passage and preventing back-syphoning of the body of liquid from the cistern; and a second collapsible valve sleeve of flexible and impermeable material freely suspended into said flow passage and open to the atmosphere at one end, said second valve sleeve being secured at one end thereof in a fluid-tight manner about the end of said third branch and having a distal end above the body of liquid in the cistern whereby said one end is retained open to atmospheric pressure, and said second valve sleeve is in a normally collapsed closed condition during normal pressurized liquid flow into the cistern due to the pressure-differential between the atmosphere and the pressurized liquid thereby closing said third branch atmospheric vent, with reversal of the direction of liquid flow and subsequent collapse of said first valve sleeve further causing said second valve sleeve to be distended by ambient atmospheric pressure to open said third branch to said second branch to interrupt any back-syphoning of the body of liquid from the cistern to the said second branch.