FILTER CASSETTE

Abstract: Filter cassette (1) adapted to be sealingly mounted against the inner wall of a well or a well cover so as to extend radially across the cross section of the well, comprising a ring-shaped space to be filled or refilled with an absorbing or active additive and a lid (5) extended radially from the area of the inner wall of the well towards a central hole (7), and an opened bottom (11), the filter cassette having a capacity to receive water streaming down that increases gradually in the radial direction mentioned and comprising a lid with a top surface, as seen in a radial direction from the periphery to the centre of the lid, which rises gradually over a horizontal plane on which the lid rests.

Description: Filter Cassette The present invention relates to a filter device for filtering oils, cleaning agents and other contaminants from drainage water before the water is led on to a purifying plant or receiver. More specifically, the invention relates to a cassette for chemical and mechanical absorption of contaminants from the water streaming through, or neutralisation or the corresponding treatment by adding material to the water streaming through, which filter is releasably entered into a floor drain, street drain or similar drain, pipe or drainpipe for reception of surface water. A cassette to be introduced into sewage wells for the purpose of adding a neutralising agent to the sewage water is previously known e.g. from Swedish Patent No. 9402460-1. The cassette according to this patent is designed to receive a certain portion of the water streaming down in order to be able to discharge, under an extended period of time, a neutralising agent contained in the cassette. A problem in designing a filter for a sewage well is the large variations in the amount of water streaming down, to which the reception capacity of the filter must be adapted, at the same time as the filter must not hinder the well's capacity to lead water away during unusually high loads. When the load is normal, the water usually streams along the walls of the well, making it desirable that a filter entered into the well should seal against these walls. Another problem in that is that plant segments and other floating matter follow the water streaming down, risking to clog up the inlet opening of a filter sealing against the inner wall of the well. It is the object of the invention to solve these problems by providing a filter with a progressive capacity of receiving water streaming in, which filter is designed to be self-cleansing from plant segments and other floating matter. The overall object is achieved by providing a filter with the features of claim 1. Embodiments of the invention will be described in the dependent claims. The invention will now be described in more detail with reference to the enclosed drawings, wherein: Fig. 1 schematically shows, in section, an embodiment of the filter cassette according to the invention, mounted in a well cover; Fig. 2 shows, in a sectional view corresponding to Fig. 1 , another embodiment of the filter cassette mounted in an alternative position in a well; Fig. 3 shows a schematic section through a lid forming part of the filter cassette, and Fig. 4 schematically shows an alternatively designed lid, forming part of the filter cassette according to the invention. With reference to Figs. 1 and 2 there is shown a filter in the form of a cassette 1 adapted to be mounted radially across the cross-section of a sewage well, such as a floor sewer, street sewer, yard well or the like, to receive surface water. The cassette is closely fitted against the inner wall of the well and may have a cross- section that is circular, rectangular or otherwise adapted to the well. The cassette 1 is supported in a frame or bracket 2, mounted in the inner wall of the well, but it may also be designed to be suspended directly from a well cover 3, under the upper lid thereof. A sealing element 4, e.g. in the form of a metal ring or an elastic element, may be provided to seal the periphery of the cassette 1 against the wall of the well, the bracket or the well cover. It will be noted that the filter cassette 1 in its mounted position also serves as a protection, preventing large objects from falling into the well. The cassette 1 is substantially designed as a pipe with double walls, and may have a substantially uniform cross-section along its entire length or have a conical shape in its outer and/ or inner periphery. The cassette is filled, between its walls, with an absorbing and replaceable material for absorbing oils, ' cleaning agents, other chemicals or particles such as clay, sand, heavy metals etc. in a ring-shaped space. Obviously, the cassette may in other applications also be filled with a material adapted to be added to passing water, for different types of active treatment, such as change in pH-value etc. For filling/ replacing of the absorbing or active material the cassette 1 has a releasable lid 5 with perforations for receiving water streaming down into the well. To adapt to varying amounts of water, the lid 5 has a plurality of openings 6 which are formed and distributed over the lid surface to give the cassette 1 a progressively increasing reception capacity in the radial direction of the lid 5, in a way that will be explained below. The cassette 1 has a preferably centred through hole 7 to let water through when the loads are exceptionally high. The hole 7 also allows for sludge uptake from the well with the aid of a hose, without the necessity of dismounting the cassette, and may be slightly conical and is, in an alternative embodiment, perforated or in another way opened to permit the filter to receive also the water that flows through the central hole 7 during higher loads, or at least parts of that water. The inside of the hole may alternatively be designed with steps, as indicated in Fig. 2, and have perforations in the substantially vertical and/ or the substantially horizontal or against the horizontal plan inclined/ weakly inclined areas of the periphery of the hole 7. The inner periphery of the cassette may in some applications be extended to stretch beyond and over the lid 5 in the form of a collar 8, see Fig. 2, wherein the collar 8 is shown diagrammatically through dash dotted lines. The height of the collar 8 may be adapted to frequent peak loads, e.g. in a washing hall, and also gives the cassette 1 a capacity to accumulate downpouring and contaminated water, in order to receive the water gradually for absorption of the contamination. The collar 8 may, like the lid described below, contain a perforation in its shell surface 9, the perforation having a gradually increasing degree of perforation seen in the height direction. The collar 8 may also comprise a covered or perforated top 10, e.g. in applications where it is possible to calculate maximum loads, e.g. in applications in wells for dewatering limited areas. The accumulating effect of the collar is preferably used to compensate for the deviation of the well or filter cassette from a perpendicular line, e.g. when the well, due to displacements in the ground, has been brought to an inclined position. The cassette 1 is further provided with a bottom 11, which may be perforated or in another way opened to let through the water received for absorption. The lid 5 of the cassette has, seen in a cross section in the direction of the lid periphery towards its central hole 7, a gradually increasing height or rise over a horizontal plane H on which the lid rests, see Fig. 3. In the inner area of the lid, the rise levels out to transform into a horizontal or arched, convex or concave (not shown) portion 12 adjacent to the hole 7. In its periphery, the lid preferably has a design that permits the lid to be snapped on to the filter cassette 1. Alternatively, the lid 5', see Fig. 4, may have, in the radial direction mentioned, a gradually increasing decline under the horizontal plane H, which at a distance from the central hole transforms into a rise with an arched end 13 around the periphery of the hole. The lid 5' has, similarly to the lid 5, a gradually increasing opening degree in a way that will be described below. In the alternative embodiment 5' of the lid, the opening degree may increase gradually in a radial direction from the centre of the lid or its most deeply located part 14 to its outer periphery. In a preferred embodiment, the lid 5 has a perforation or openings 6 with an opening degree that gradually increases or progresses in the direction of the lid periphery towards its central hole 7. For that purpose, the lid may be designed with openings that are circular, oval or of other shape, the peripheral openings possibly being fewer than the inner openings, or being smaller than those. The gradually increasing height of the lid 5 over the horizontal plane, and the progressive opening degree in a direction from the periphery to the centre of the lid co-operates in a beneficial way to firstly spread the water that streams down and is received over the cross section of the filter and the filter mass, and secondly keep the filter clean from plant parts falling down and other matter risking to clog up the peripheral openings of the lid. When larger amounts of water stream down, the upper side of the lid is gradually filled with water for which there is no time to be received by the peripheral openings, causing leaves and other plant parts to float up and pass, when the lid is over-filled, the flat or convex, or alternatively concave, shaped portion 12 and stream down through the central hole 7. Through the releasable lid 5, the filter cassette 1 may be filled and refilled with absorbing material to absorb contamination from the water streaming down. Such absorbing material may be chosen to separate e.g. oil, cleaning agent or other chemicals, sand, clay and other particles from the water. Obviously, the filter cassette may be filled with neutralising or active material adapted to be added to the surface water before this is received by a purifying plant or receiver, alternatively or in combination with the mentioned absorbing material. The filter cassette 1 may be formed of e.g. steel, natural material or synthetic material, or a combination of these materials.

Claims: CLAIMS 1. Filter cassette (1) adapted to be sealingly mounted against the inner wall of a well or a well cover so as to extend radially across the cross section of the well, comprising a ring-shaped space to be filled or refilled with an absorbing material or active additive and a lid (5), radially extended from the area of the inner wall of the well towards a central hole (7), and an opened bottom (11), characterised by a gradually increasing capacity, seen in said radial direction, to receive water streaming down. 2. Filter cassette according to claim 1, characterised in that the lid (5) has a gradually increasing opening degree in the radial direction. 3. Filter cassette according to claim 2, characterised in that the lid (5) has openings (6) with a gradually increasing area of opening and/or number in a radial direction from the periphery to its central hole. 4. Filter cassette according to claims 1 and 2, characterised in that the lid (5), seen in a direction from it periphery towards its centre, has a rise towards a horizontal plane (H) on which the lid rests, the rise levelling out or transforming into an arched, convex (12) or concave part in the area of the lid centre. 5. Filter cassette according to the previous claims, characterised in that its inner periphery is extended to a collar (8) projecting above the lid for accumulating an amount of water streaming down, which gradually flows off through the openings (6) in the lid (5). 6. Filter cassette according to claim 5, characterised in that the collar (8) has perforations in its shell surface (9) with a gradually increasing opening degree in the direction of the top of the collar. 7. Filter cassette according to claim 5, characterised in that the collar has a covered or perforated top (10). 8. Filter cassette according to the previous claims, characterised by a central through hole (7), perforated in its inner periphery or shell surface. 9. Filter cassette according to claim 8, characterised in that the central hole (7) has a cross section area that gradually decreases downwards. 10. Filter cassette according to claim 8, characterised in that the hole (7) has an inner periphery that is step-shaped in an axial section. 11. Filter cassette according to claim 8, characterised in that the hole (7) has a smooth and continuous shell surface. AMENDED CLAIMS [received by the International Bureau on 20 April 1999 (20.04.99); original claims 1-11 replaced by new claims 1-7 (2 pages)] 1. Filter cassette (1) adapted to be sealingly mounted on the inner wall of a well or a well covering so as to extend radially over the section of the well, comprising a tube member having two coaxially extended walls, the walls forming an annular space adapted to be filled and refilled, resp., by an ab- sorbant or reagent fill material, a central hole (7) extended through the cassette and a perforated bottom member (11), attached to the lower ends of the tube walls, and a perforated lid member (5,5'), resting on the upper ends of the tube walls so as to seal by the periphery thereof, directly or indirectly (2,4), with the inner surface of the well, the lid member having an opening corresponding to the central hole (7) and the lid member (5,5') being formed to provide a gradually increasing capacity, as seen in a radial direction towards the central hole (7), for receiving down- streaming water, whereby the lid member has a perforation (6) of holes in gradually increasing numbers or gradually increasing opening area in said radial direction, characterized by said lid member (5,5') being formed to have a capacity for momentarily holding a volume of water that is accumulated on top of the lid member, at least until the excessive water volume is evacuated through the central hole (7), said capacity being provided in that the lid member (5,5') is formed, at least partially to rise, as seen in radial direction from the periphery thereof towards its center, from a horizontal plane (H) wherein the lid member is positioned, said rise leveling out or, preferably, transforming into an arch shaped, convex area (12; 13) in vicinity of the central hole (7). 2. Filter cassette (1) according to claim 1, characterized by an inner periphery which is extended by a collar (8) to reach above the lid member (5,5'), said collar (8) being adapted to hold a volume of water which gradually escapes through the openings (6) of the lid member. 3. Filter cassette (1) according to claim 2, characterized by said collar (8) having a perforated (9) cylindrical wall, the perforations (9) having a gradually increasing opening area towards the top edge of the collar (8). 4. Filter cassette (1) according to claim 2, characterized by the collar (8) having a perforated or a non-perforated cover. 5. Filter cassette (1) according to one of the above claims, characterized by a central through hole (7) having a perforated inner surface. 6. Filter cassette (1) according to claim 5, characterized by the central hole (7) having a gradually decreasing opening towards its lower end. 7. Filter cassette (1) according to claim 5, characterized by the central hole (7) having a stepped inner surface, as seen in a vertical, longitudinal section thereof. STATEMENT UNDER ARTICLE 19 The applicant hereby submits a new set of claims 1 to 7, in replacement of originally filed claims 1 to 11. The International Bureau is therefore requested to replace the original sheets of pages 6 and 7, resp., by the new pages 6 and 7 filed with this communication. In the new claim 1 , the characterizing features of original claims 1 to 4 are incorporated to separate the invention over prior art. The new claims 2 to 7 correspond to original claims 5 to 10, minor corrections of wording being introduced for correlation with the wording of new claim 1. Original claim 11 is cancelled. The International Bureau is hereby requested to incorporate the new set of claims 1 to 7 in the publication of the application, in replacement of the original claims.

Inventors: ELOFSSON BIRGER, ELOFSSON, BIRGER
Applicants: ELOFSSON BIRGER, ELOFSSON, BIRGER
Application year: 1998
Main classification: E03F5
IPC codes: E03F5