Patent ID: 6874521

Claim:
A regulating valve as comprising (A) a housing which has a high pressure chamber and a low pressure chamber formed therein; (B) a valve seat which is disposed in said housing between said high pressure chamber and said low pressure chamber; and (C) a valve element which is disposed in said housing and which is selectively movable, upon a pressure drop in said low pressure chamber beneath a designated pressure through a valve opening stroke extending between 1) a fully closed position in which said valve element seals against said valve seat to prevent fluid flow from said high pressure chamber to said low pressure chamber, and 2) a fully open position in which a maximum inlet flow area of said valve element is open to permit fluid to flow from said high pressure chamber to said low pressure chamber at a maximum rate, and wherein said inlet flow area of said valve element increases continuously for at least a substantial portion of the opening stroke of said valve element so that the rate of fluid flow through said valve increases throughout said substantial portion of the valve element stroke, wherein, during the valve opening stroke, a flow rate from said high pressure chamber to said lower pressure chamber varies at least generally proportionally with the pressure drop in said low pressure chamber through at least a substantial portion of the valve opening stroke of said valve element, wherein said regulating valve comprises three modular units one of which includes a diaphragm trapped between the other two units, and wherein the other two units each include a seal holder threaded into a bore in a valve body and an annular lip seal mounted in said holder in sliding contact with said valve element.