Excess flow valve

Claim 1

An excess flow valve, comprising: (a) an elongate valve housing having a flow passage extending therethrough, an upstream portion of said housing defining a valve seat; (b) a valve stem disposed in said housing and extending through said flow passage for reciprocal movement therein, said valve stem being provided with a substantially flat valve disc at its upstream end for cooperating with said valve seat to open and close said flow passage; (c) a lever pivotally mounted to said valve stem and extending outwardly therefrom for reciprocally driving said valve stem, said pivot being of the lost motion type; (d) a two-arm lever pivotally mounted with respect to said housing, said two-arm lever being rigidly affixed to said first mentioned lever and disposed perpendicularly thereto; (e) a spring carried by said valve housing and engaging one end of said two-arm lever to bias said two-arm lever in a first direction to open said flow passage, and means carried by said valve housing for adjusting the tension of said spring; (f) selectively actuable means for applying a motive force connected to the other end of said two-arm lever to move said two arm lever in a second direction to close said flow passage; and (g) wherein said adjusting means is adapted for adjusting the distance of said valve disc to said valve seat in a quiescent state by adjusting the tension of said spring, wherein said spring serves to bias said valve disc to an open position unless and until there is a drop in pressure on the downstream side of said disc and whereas said motive force applying means is utilized for closure of the flow passage irrespective of the pressure created by a medium flowing through the flow passage.