Hermetically sealed valve with fixed diffuser

摘要

A hermetically sealed valve includes a valve body having an annular seat adjacent the valve inlet with a frusto-conical surface diverging outwardly therefrom toward the valve outlet and a fixed diffuser assembly including a fixed disc guide and a slidable spring biased closure disc. The disc guide has a diverging frusto-conical surface spaced from the first surface to define a high efficiency annular diffuser flow passage. The fluid exposed surfaces of the disc are located upstream of the passage. The closure disc is actuated between an open position and a closed position by an axially movable valve stem acting on a flexible diaphragm. The pressure drop in the diffuser passage at high flow conditions establishes a force differential on the diffuser assembly acting toward the valve seat which is borne entirely by the disc guide thereby eliminating any pull down forces on the closure disc.