UNOBSTRUCTED LOW PRESSURE OUTLET AND SCREEN GRID FOR A HIGH PRESSURE FEEDER

A rotary high pressure feeder for processing cellulosic fibrous material including: a rotor rotatable about an axis and comprising at least one pocket comprising a conduit extending through the rotor in a direction perpendicular to the axis and having end openings at opposite ends of the pocket, wherein each of said end openings of each pocket functions as both an inlet and outlet depending upon an angular position of the rotor within a housing; the housing encloses said rotor and said housing includes a low pressure inlet port and a low pressure outlet port aligned vertically, and a high pressure inlet port and a high pressure outlet port aligned horizontally, wherein the ports are arranged on the housing for registry with the end openings of at least one pocket, and a screen grid seated in or adjacent to the low pressure outlet port, wherein the screen grid includes an array of screen slots and bars forming a uniform pattern of slots and bars extending without interruption across an entirety of the low pressure outlet port.