Vacuum breaker

Abstract

A vacuum breaker is adopted for use on a water discharge end of a flush valve in a water supply piping system. It includes a valve which has a valve seat with a hollow section to house a plug. The plug is movable up and down under water pressure and a spring on the bottom to actuate flushing or stop flushing. The vacuum breaker further includes a coupling duct and a bushing housed in the coupling duct that is made from a flexible material. The coupling duct has a plurality of apertures near the top end. The outer wall of the bushing and the inner wall of the coupling duct form a gap therebetween. During flushing, the wall of the bushing is expanded outwards under water pressure to close the apertures to stop water overflow through the apertures. When the flushing stops, external air can enter through the apertures and the gap between the coupling duct and the bushing to balance the internal and external pressure and eliminate vacuum, and prevent back siphonage from occurring.

1 . A vacuum breaker adopted for use in a water discharge end of a flush valve in 
 a water supply piping system, comprising: 
 a valve having a valve seat screwed on the water discharge end, the valve seat having a hollow section to house a plug which is movable up and down, the plug being coupled with a retaining ring on the bottom thereof;  
 a coupling duct located below the valve having a first flange on the top end, a plurality of apertures formed on the wall abutting a lower side of the first flange, and a coupling end on a distal end opposing the first flange;  
 a spring having one end pressing the bottom of the plug and other end coupled on a center strut located in the coupling duct;  
 a bushing housed in the coupling duct being made from a flexible material and formed in a barrel which has two open ends, and having a second flange on a top end; and  
 a nut having internal screw threads to screw the coupling duct and the rest elements in the water discharge end of the flush valve.  
   
   
   
       2 . The vacuum breaker of  claim 1 , wherein the retaining ring seals the bottom end of the valve seat when flushing stops.  
   
   
       3 . The vacuum breaker of  claim 1 , wherein the plug has a cross rib on a upper side to form a plurality of water inlets corresponding to the hollow section of the valve seat to divide water flow.  
   
   
       4 . The vacuum breaker of  claim 1 , wherein the bushing has an outer wall in contact with an inner wall of the coupling duct when flushing stops.  
   
   
       5 . The vacuum breaker of  claim 1 , wherein the coupling duct has an outer wall which forms a gap with an inner wall of a distal end of the nut.