Combination anti siphon and shut off plastic valve

Claim 1

In a valve, the combination comprising a. a chamber and an annular elastomer, main seat therein, there being a chamber outlet, b. a stem projecting through the seat with clearance therefrom, the stem carried by the chamber at one side of the seat, c. an externally accessible handle operatively connected with the stem to rotate same, d. a stopper having connection with the stem and operable to engage and disengage the seat at the opposite side thereof and in response to stem rotation, e. the chamber having a liquid pressure inlet to communicate said pressure to the stopper for transmitting pressure loading to the seat when the stem is rotated to engage the stopper against the seat, whereby the stopper will remain closed against the seat irrespective of liquid pressure or temperature change induced expansion and contraction of the housing, f. a vacuum breaker ring extending closely about the stem to slide along smooth surface extent of the stem at the side of the main seat opposite the stopper, the chamber defining an air inlet passage closed by the ring when the stopper disengages the main seat to pass pressurized liquid to said ring and said outlet, and the ring having another position in which a ring boss projects between the stem and the seat to seal off flow through the main seat excepting that reduced clearance is then provided between the stem and ring proximate the seat to pass air to the inlet side of the stopper in response to vacuum application to said liquid outlet, g. the stopper and stem both consisting of plastic material, and h. the stem and stopper having rotary threaded interconnection at the side of the seat opposite the ring and there being a tongue and groove connection between the stopper and said chamber to block rotation of the stopper in response to stem rotation to displace the stopper toward and away from the main seat.