Flow control valve assembly

Abstract

A fluid condition controlled mixing valve assembly includes a valve body having a warm fluid inlet, a relatively chilled fluid inlet, a fluid mixing chamber, and a fluid outlet in communication with the mixing chamber. A thermally responsive control member, or thermostat, is disposed within the mixing chamber. A cylindrical liner is situated within the valve body with openings for chilled fluid flow and warm fluid flow. Concentrically located piston and valve disc are connected through an actuator to the thermostat so that the piston and disc move according to the thermostat response to the fluid temperature in the mixing chamber. The piston controls flow through the fluid openings. The liner and the shuttle define primary and secondary passageways. Fluid flows through the primary passageway when the flow control member is in a normal operating condition, i.e., with substantial fluid flow through both inlets. If flow through one of the inlets ceases, the shuttle moves to a failure condition, in which substantially all flow from the inlets is directed through a secondary passageway. This provides a fluid of a desired condition when there is substantial flow through both inlets and a fluid of a less desirable but acceptable condition when substantial flow through one of the inlets ceases.