Flush valve improvements for controlling flushing volume

A flush valve including a body having an inlet and an outlet, a valve seat at said outlet, valve means movable in said body toward and away from said valve seat to control flow from said inlet through said outlet, a chamber in said body above said valve means, a refill orifice in said valve means connecting said chamber with said body inlet, pressure in said chamber maintaining said valve means closed upon said valve seat, the size of said refill orifice controlling the time to fill said chamber from said inlet which determines the time of flow of water from said inlet through said outlet,

• a relief valve associated with said valve means for venting said chamber to said outlet, means for opening said relief valve to vent said chamber causing said valve means to move away from said valve set to open flow through said outlet,
• said body having an inwardly directed flange, said body having inwardly directed threads spaced from said flange, a seal ring having a plurality of spaced outwardly extending lobes seated on said flange, with said lobes locating said seal ring relative to said body in the space between said flange and said threads,
• a cover threadedly attached to said body by said threads, said cover bearing against said ring whereby said ring forms a seal between said cover and said body, said seal ring being formed from a low density polyethylene elastomeric material with a surface finish of sufficient lubricity such that the cover will slide upon the ring surface when the cover is threadedly attached to said body, said seal ring having sufficient elastomeric characteristics such that it distorts under pressure from said cover to form a tight seal between said cover and said body.