On-off sprinkler

Claim 1

A water sprinkler device for a fire protection system coupled to a pressurized fluid supply line; comprising in combination: a sprinkler body having an annular inlet portion adapted for coupling to said fluid supply line; means providing an inner wall for dividing said sprinkler body into a first bifurcation, having an outlet portion that defines a main fluid flow passageway between said inlet portion and said outlet portion, and a second bifurcation that defines a control chamber; a deflector mounted adjacent said outlet portion to deflect fluid flow therethrough; means providing a valve seating surface abutting said inlet portion at the junction of said bifurcations; a main valve disposed in a direction downstream from said seating surface and having a valve seat mounted in opposed relation to said seating surface so as to oppose fluid pressure from said inlet portion that tends to cause said valve seat to separate from said seating surface to open said valve, said main valve being slideable into said control chamber for controlling fluid flow through said main passageway while maintaining said control chamber blocked to fluid flow from said outlet portion, an aperture formed substantially centrally in said main valve to define a control passageway that couples fluid from said inlet portion to said control chamber; said main valve exhibiting a first surface area disposed toward said control chamber that is greater than a second surface area disposed toward said inlet portion to provide a greater main valve closing pressure than opening pressure, means providing an outlet port from said control chamber to release fluid pressure therefrom to open said main valve, pilot valve means having a valve member mounted to control fluid flow through said outlet port and including a bimetallic disc centrally connected to said valve member, and means for securing the peripheral edges of said bimetallic disc against movement relative to said sprinkler body so as to flex said disc in a manner to resiliently bias said valve member to close said outlet port, said disc responding to temperature rise to snap to an opposite flexure to open said outlet port to release fluid from said control chamber to open said main valve.