Diffuser valve

Claim 1

A controllable anti-compaction device for hopper stored particulate materials, comprising: a valve having a valve body secured within a wall of a hopper; a substantially planar ring-shaped valve seat of said valve body positioned substantially in co-planar relationship with an adjacent inner-wall surface of said hopper; a valve member having a valve head cooperable with said valve seat, and positioned within the interior of said hopper, said valve member and valve head being moveable axially between a first position in which a peripheral skirt of said valve head is in seating engagement with said valve seat and an outer peripheral edge of said valve head is positioned closely adjacent to an end wall of said valve body; and a second position in which said valve head is spaced from said valve seat and said peripheral edge is spaced from said end wall to define, in conjunction with said end wall, a ring-shaped ejection orifice for compressed air operative to direct compressed air at high velocity in a substantially laminar flow radially of said valve member and in substantially parallel relationship with said inner wall of said hopper; and fluid operated means for controlling movement of said valve head between said first and said second positions; said fluid operated means being operative to progressively move said valve head towards said first position against forces exerted on said valve head by said compressed air, in order to progressively increase the velocity of said compressed air exiting said valve as said valve head moves toward said second position, and, to purge and scavange particulate matter from beneath said valve head.