Patent ID: 7780815

Claim:
In a rotary drum for condensing pulp from a pulp slurry vat, the drum including radial conduits delivering filtrate from a pulp mat on an outer surface of the drum to at least one filtrate conduit coaxial with a drum rotational axis, a valve segment in the filtrate conduit comprising: an outer surface of the valve segment juxtaposed against drainage outlets of the radial conduits as the conduits pass through an angular range extending from an upper drum position to an immersed in a vat position, wherein the valve segment does not block the drainage outlets during a majority of the rotation of the drum; at least one gas aperture on the outer surface of the valve segment, where the at least one gas aperture is aligned with the drainage outlets, and said gas aperture extending at least a majority of a width of the outer surface of the valve segment, and a closed passage extending from the at least one gas aperture to a gas vent external to the filtrate conduit, wherein the closed passage is offset from and extends above and below the horizontal centerline of the filtrate conduit.