Adjustable skip bridge valving mechanism for disc filter

Claim 1

In a vacuum disc filter having a plurality of discs disposed in spaced relation along a rotatable hollow shaft each disc being composed of a plurality of radially extending, filter mediacovered filtering sectors whose hollow interiors communicate with suction lines located within the hollow shaft and extending to a valving mechanism at one end of said shaft, said valving mechanism consisting of a multi-ported vlave head in communication with vacuum lines and with compressed air lines, said valving mechanism being programmed to effect sucking in sectors which are immersed in slurry and sectors undergoing drying and to effect an application of air at superatmospheric pressure in sectors withdrawn from slurry and about to be rotatably returned to such slurry, the improvement whereby overall dryness of filter-cake can be enhanced which improvement consists in that said valving mechanism includes a skip bridge valve head comprising (a) a stationary bridge plate having slots for a lower pick-up port and an upper pick-up port, a drying port and a snap blow port, and (b) a wear plate fixed to the end of the shaft and rotatable therewith in sliding engagement with said bridge plate there being in said wear plate as many spaced peripheral apertures as there are sectors per disc each said peripheral aperture being associated with at least one oF the aforesaid lines and said peripheral apertures being separated from each other by intervening lands, said peripheral apertures registering with said slots, said slots being so much narrower than are the lands between the peripheral apertures of the wear plate as to prevent overlap or sharing between any two adjacent tubes and to ensure that application of vacuum to the pick-up ports is confirmed to only one line or row of sectors, at a time.