Backflow preventing apparatus for water closets

摘要

An automatically activated backflow prevention device for water closets or toilets is provided having a substantially cylindrical support member terminating in one end in a cam shaped end for mating with a hinged flapper valve having a parabolic shaped or upwardly curving upper surface and correspondingly shaped sealing member disposed therebetween for mating with the cam shaped end of the substantially cylindrical support member. An elastomeric hinge member is provided for connecting the closure member or flapper valve to the substantially cylindrical support member so that when closed the flapper valve or closure member conforms to the confronting cam shaped end of the cylindrical support member with the sealing member disposed therebetween. A backflow water pressure responsive assist member is optionally provided on the lower surface of the closure member to assist in the closure of the closure member in response to backflow water pressure from waste pipes.