Liquid purification or separation – With repair or assembling means – Hoist or handle means
Reexamination Certificate
2001-12-13
2004-11-02
Cecil, Terry K. (Department: 1723)
Liquid purification or separation
With repair or assembling means
Hoist or handle means
C210S484000, C210S496000, C210S497010, C210S463000
Reexamination Certificate
active
06811692
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention pertains generally to filters for use in waste water treatment, particularly to filters intended for filtering liquid effluent exiting a septic tank prior to final introduction of the liquid to a distribution field. The invention has utility in both gravity fed septic to field distribution systems as well as in pumped outlets such as those used in low pressure mound sanitary drainage systems.
Conventional drainage fields for receiving the output of septic tank sewage effluent are generally in the form of network of perforated finger pipes connected to an outlet of the septic tank and situated in trenches on top of a filter bed generally consisting of rock, crushed stone, gravel, sand, or a combination thereof. Such systems normally operate by gravity flow, however, it is common practice to connect a pump to the septic tank to aid in moving the sewage effluent from the septic tank and through the drainage field, particularly where required by the lay of the land or other criteria leading to the adoption of such a design. The sewage effluent is distributed through the network of perforated pipes and trickles onto and through the filter bed, where its nutrient content is reduced by microbial action. After passing through the filtering material, the sewage effluent is absorbed by the soil surrounding and underlying the trench. Critical to the continued operation of such a system is the maintenance of an open system of perforations in the pipes connected to the outlet of the septic tank as well as in the filter bed and underlying soil. Usefulness is limited, however, by clogging of the openings in the drain field finger pipes, stone, sand, and soil pores from semisolid debris flowing from the septic tank or by solids such as leaves and grass which can enter the effluent tank during servicing or resulting from a loosely fitting effluent tank cover. As the pipe openings, filter bed, and underlying soil become blocked, flow of effluent is reduced and the sanitary drainage system can be rendered inoperative.
In order to prevent the drain field finger pipe openings, filter bed, and underlying soil from clogging, solid material present in the effluent should be removed prior flow into the drain field. Currently available effluent apparatus include filtering devices having a filter disposed in fluid connection between the septic tank and the drain field, such as those described in U.S. Pat. Nos. 3,332,552; 4,710,295; 5,382,357; 5,580,453; 5,593,584; 5,683,577; 5,762,790; 5,762,793; 6,136,190; and 6,267,882. Other filters have been employed at the input of an effluent pump, for instance those devices and systems described in U.S. Pat. Nos. 5,492,635; 5,427,679; and 4,439,323, and filters in fluid connection to the input of a septic pump, as described, for instance, in U.S. Pat. No. 5,582,716. Solid material present in effluent should be removed prior to the flow into the drain field and can be filtered by such devices, thereby helping to prevent clogging. However, the filtering orifices defined by these devices do not filter efficiently and effectively, and frequently become clogged, requiring cleaning and servicing of the filtering apparatus.
Common to many of the filters disclosed in the prior art is a canister wall or housing in which the filter is located. When the filter becomes clogged and requires cleaning or replacement, many filters lose some or most of the debris that has been held back. Frequently, the entire canister needs to be removed from the fluid piping or chamber system in which it is installed. Frequently, the outlet tees containing the canisters are not aligned with an access port to the septic tank in which it is located, thus requiring some manipulation of the clogged canister during removal or replacement, making most current filters unusable because of their rigidity. Any manipulation tends to disturb some of the material extracted by the filter, making the whole process somewhat disagreeable, and contributing to the outflow of particulate matter into the finger field, which is just what the filter is intended to prevent. Even more disagreeable are those filters in the prior art that, due to the high initial cost, are often disassembled, cleaned and reinstalled rather than being simply withdrawn and replaced with a new filtering unit.
What is needed is a low cost filtering element. What is also needed is a filtering element that is light weight and flexible even in cold climates so that it is easily replaced even in less than optimum physical arrangements. What is further needed is a filtering element that is sufficiently adaptable to fit a variety of sizes of filtering chambers, tees and baffles. What is additionally needed is a replacement kit that provides a means for preventing outflow of particulates into the finger field during the filter replacement process. What is also needed is a filter having a large total filtering surface area so that efficient and effective filtering action occurs at good flow rates. What is further needed is a filter that can remove the smallest particulates of hair, tissue, lint, and other materials yet is easily replaced and properly discarded at the end of its useful life.
SUMMARY OF THE INVENTION
A filter element of the present invention is intended for use in waste water discharge systems. The filter element generally comprises an axial support of a pre-selected length. A handle is fixed to the axial support to facilitate the placement and withdrawal of the filter element. A plurality of bristles are fixed to and extend radially outward from the axial support to an outer margin. The outer margin of the bristles defines a substantially continuous surface generally symmetric about the axial support. The outer margin generally includes a plurality of portions defining a first selected radius of the filter element. At least two of the plurality of portions are separated by an intermediate portion wherein the bristles terminate short of the first selected radius.
The axial support desirably occupies as little of the cross-section of the filter as possible. The axial support is preferably somewhat flexible to ease the installation and withdrawal of the filter element. The can be achieved by having the axial support comprise a spiral wound set of wires, the bristles being captured between the set of wires. The wires can be of any suitable material such as galvanized steel, aluminum, or stainless steel, the stainless steel being preferred due to the longevity imparted to the filter by such a construction.
The bristles can be straight, crimped, convoluted or otherwise shaped to maximize the filtering efficiency of the filter without presenting undue back pressure to the passing fluid. While the bristles can have a cross-section that is round or oval, they preferably have a cross-section that enhances the surface area of the bristle fibers such as hexagonal, pentagonal, square, triangular, or even star shaped to enhance the small particle filtering capacity. The bristles should be somewhat flexible to aid in the installation and withdrawal of the filtering element. The bristles should also be resilient or shape retentive so that upon placement of the filter element into a chamber, the filtering element will generally self align in the middle of the chamber and will not be significantly deformed by the flow of fluid through the filter, even when partially loaded with extracted particulate material from the waste water. The bristles are desirably resistant to biological degradation and generally inert to the typical chemicals present in waste water. Suitable materials for forming the bristles include synthetic polymeric materials such as aliphatic polyamides, aromatic polyamides, polyolefins, polyvinyl chloride, polyurethane, fluoropolymers, polyvinylidene chloride, polystyrene and styrene copolymers, and particularly polyesters, polypropylene, polyethylene or nylon. The outer margin of the bristles is generally axially symmetric with respect to the axial support, but is not of uniform diameter thr
Cecil Terry K.
Sim-Tech Filter, Inc.
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