Filter
OwnerRobert L. Alldredgeinventor
Life of this patent
Estimating the term…
Abstract
An upwash, upflow, graded sand filter has a reusable imperforate diaphragm on the top of the graded filter media and an inlet for pressurized fluid above the diaphragm for inflating the diaphragm against the media during filter stage. The filter housing is flared upwardly and outwardly at selected portions to reduce the velocity of upflowing liquid during wash stage for improved grading of the filter media. A natural foraminous layer may be self-grading at the top of the filter media, allowing a circumferential outlet for filtrate. A layer of fine, dense filter media may also be used to increase the size range of media particles in the filter. Special diaphragms may be composed of individual leaflets that float above a dirty-liquid outlet during wash stage, but that sink due to a change in density when the filter is pressurized for filter stage.
Claims18
An improved upflow, upwash filter of the kind having granular filter media a portion of which is self-graded upwardly from coarse to fine, held in stationary position during filter stage;
- a filter housing containing said granular filter media within the bottom and sides of the housing;
- first liquid inlet means near the bottom of said granular filter media for admitting liquid to clean the granular media during wash stage;
- and liquid outlet means for discharging filtered liquid;
- wherein the improvement comprises:
- (a) a reuseable, substantially imperforate diaphragm means moveable between an applied position during filter stage for compressing and holding the filter media in place and a released position during wash stage for allowing the filter media to be lifted by liquid from said inlet means;
- (b) liquid overflow means located in said housing above the level of the granular filter media during filter stage for removing liquid flowing through the media during wash stage;
- (c) fluid admission means located above said diaphragm means for supplying pressurized fluid to the upper side of the diaphragm means during filter stage to move the diaphragm means from released to applied position;
- (d) fluid release means located above said diaphragm means for releasing pressure from the upper side of the diaphragm means during wash stage to allow the diaphragm to assume released position.
An improved upwash, upflow filter of the kind having graded granular filter media held in stationary position during filter stage and raised from stationary position by wash liquid during wash stage, wherein the improvement comprises:
- a filter housing containing said granular filter media and having upwardly and outwardly flared sides for reducing the upward velocity of wash liquid passing through the filter media contained between the flared sides during wash stage, wherein the housing has a wash liquid overflow near the upper end thereof and a wash liquid inlet near the lower end thereof and is characterized by a lack of constriction in the upward direction between the inlet and overflow for allowing improved selfgraded settling of the filter media after wash stage.
Dependencies are inferred from the claim text.