Flush valve and flapper, and method of ensuring a good seal between a valve seal and a valve seat

摘要

A flapper for a flush valve includes a relatively rigid backing plate and a relatively flexible valve seal. The backing plate includes structure for preventing the seal from being urged into sealing engagement with the backing plate, thereby preventing an air-filled cavity from forming between the seal and the lower surface of the backing plate. The preventing structure may include at least one pair of oppositely spaced ridges extending a first predetermined distance from the lower surface of the backing plate and forming a channel therebetween. The preventing structure may alternately include at least one radially extending channel formed in the backing plate and having a predetermined depth.