Liquid sand filter
OwnerRobert L. Alldredgeinventor
Life of this patent
Estimating the term…
Abstract
An upwash sand filter with a diaphragm hold-down for the granular filter media during filter stage is operable with self-graded coarse-to-fine media for upflow filtration, downflow filtration, or combined up and down flow to a central exit filtration. The media is held in place by a diaphragm that may be a perforated plate for allowing liquid to pass through the perforations, and in the downflow embodiment, the media column is supported on another perforated wall or plate to allow a final lower layer of coarser media to be used so that the plate itself is not the finest layer of the filter. In the upflow embodiment, a coarser top layer is employed for this same purpose. The diaphragm serves in all embodiments to prevent loss of media and avoid channeling through the media thereby allowing exceptionally high filter rates.
Claims10
An improved upwash, self-graded sand filter of the kind having a column of granular filter media held in a stationary position during filter stage and graded from coarse to fine in the direction of filtration, and a filter housing containing the filter media within the bottom and sides of the housing, wherein the improvement comprises:
- (a) wash liquid inlet means near the bottom of said granular filter media in the housing for supplying wash liquid to lift the granular filter media;
- (b) wash liquid outlet means in said housing above said stationary position of the filter media during filter stage for removing dirty wash liquid;
- (c) reusable diaphragm means moveable between an applied position against the top of said filter media column during filter stage for compressing and holding the filter media in place, and a release position during wash stage above the stationary position of the filter media in filter stage for allowing the media to be lifted by the upflow of liquid from said inlet means;
- and
- (d) actuator means for holding the diaphragm in applied position during filter stage and releasing the diaphragm from the column of filter media during wash stage.
Dependencies are inferred from the claim text.