Abstract: A fryer system has a tub and a filter screen assembly located in the tub to filter cooking fluid. A filter pan or crumb catcher having a perforated surface is positioned above the tub to receive cooking fluid from a cooking vat of the fryer system. A pan is positioned between the filter pan or crumb catcher and the tub to receive cooking fluid and direct it to the tub, with the pan extending beyond outer edges of the filter screen assembly to substantially prevent the flow of cooking fluid from the filter pan or crumb catcher directly onto the filter screen assembly.

Abstract: A filter and housing for waste water treatment includes a housing having a plurality of coaxially mounted vertically extending sections adaptable to receive a filter cartridge therein. An upper section is provided with an outlet consisting of at least two coaxially aligned rings of preselected diameters wherein the thickness of the rings and the spacing between the rings is sufficient to receive waste water treatment outlets of different diameters. The filter cartridge is comprised of a stacked arrangement of a plurality of disc-dam units wherein each disc-dam unit is provided with a serpentine configured first dam, the first dam extending upwardly from an upper surface of the disc-dam unit, the first dam having terminating ends spaced at outer terminating edges of the disc dam unit to define a cord segment therebetween. The terminating ends are connected by a second dam having a height less than the first dam.

Abstract: A screening screen assembly for a vibratory screening machine including an apertured plate, and a subassembly of an undulating support screen and fine screening screen and finer screening screen bonded to each other by a fused plastic grid and bonded to the apertured plate. A method of fabricating a screening screen assembly for a vibratory screening machine including the steps of providing a support screen, superimposing a plastic grid onto the support screen, superimposing a finer screening screen onto the fine screening screen, applying heat and pressure to the superimposed screens to fuse the plastic grid and thereby form a flat bonded laminate subassembly by causing the fused plastic grid to permeate the fine screen and the finer screen and the support screen, forming the bonded laminate subassembly into an undulating shape, providing an apertured plate, and bonding the undulating bonded subassembly to the apertured plate.

Abstract: A screen assembly for a vibratory separator, the screen assembly having a first screen portion having a first end and a second end spaced apart from the first end, and a second screen portion formed integrally of or connected to the second end of the second screen portion. A screen assembly with a first portion of screening material and a second raised portion of screening material, the second raised portion extending from a material introduction end of the screen assembly to a material exit end thereof, the raised portion, in one aspect, culminating in an apex above the first portion of screening material.

Abstract: A coalescing element is provided which is capable of separating a continuous phase fluid from a discontinuous phase fluid. The coalescing element includes a wrap structure which facilitates the coalescing process by conglomerating smaller droplets of the discontinuous phase fluid into larger droplets which may be of a size that will prevent them from being re-entrained.

Abstract: A filter media testing arrangement and method including a flow-through test tower composed of a preselected number of clamped modular rings capable of supporting test samples in adjacent or spaced position therein so as to comparatively measure and control pressure drop and particulate separation characteristics of test sample media.

Abstract: There is proposed an apparatus for isolating and recovering an objective cell, which comprises, a filtering device having a filtering member which is capable of setting a porosity thereof to two or more different porosity, a first line for feeding a priming liquid to the filtering device, a second line for feeding a liquid to be treated containing the cell aimed to isolate to the filtering device, and a third line provided with a storage container for storing the priming liquid that has been passed through the filtering device, wherein the priming liquid stored in the storage container is employed for washing the filtering device. There is also proposed a method for isolating and recovering an objective cell using the aforementioned apparatus.

Abstract: A method for separating fluid from a mixture of fluid and fibrous lost circulation material, the method including introducing the mixture onto a screen assembly that is vibrating for passage of the fluid through the screen assembly and for separation of fibrous lost circulation material from the fluid, the screen assembly comprising a plurality of screens one on top of the other and including at least a first screen and a second screen, one of the screens with comprising a screen mesh woven with non-square openings as viewed from above.

Abstract: A drain filtering system is disclosed, comprising a filter placed within a basket which is suspended from frame positioned underneath a drain grate atop the inlet to a storm drain. The filter is constructed from materials which filter out heavy metals and hydrocarbons from the water passing through. The filter also has overflow outlets to prevent back-up of storm water during periods or heavy rain. The basket is constructed from a corrosion resistant material, preferably high density polyethylene which can withstand the extreme pressures exerted by waste and water collected within the filter.

Abstract: Filter elements for draining wastewater into the soil in leach fields comprise net sacks filled with scrap rubber or plastic chips and supplied with fabric filter cloth. Leach fields are constructed by excavating trenches, placing a first row of filter elements at the bottom of the trenches, installing a drain pipe on top of the row of filter elements, placing a second row of filter elements on top of the first row and the drain pipe, overlapping the pieces of filter cloth to provide a barrier to the surrounding soil, and backfilling the trench with soil.

Abstract: ‘A Portable Multi-Strainer (11)’ for a kitchen sink comprising a filter screen (14) having a top and bottom surface, a top grid (12) having openings therein abutting the top surface of the filter screen (14), a bottom grid (15) having openings therein abutting the bottom surface of the filter screen (14), said strainer (11) being sized to cover the entire bottom of said kitchen sink and having a thin edge (18) border (17) adapted for a tight fit to the walls of said sink. The top grid (12) openings therein comprise numerous cells (13) all having top and bottom openings. Cells' (13) bottom openings abutting the top surface of the filter screen (14), ‘coinciding’ with the bottom grid's (15) openings abutting the bottom surface of the filter screen (14), resulting with all cells (13) functioning as many individual strainers, having waste particles retaining inside the cells (13) as water drains through filter screen (14) and the bottom grid's (15) openings.

Abstract: A filter assembly for use in a press mould for moulding of cementitious products, the filter assembly including a fabric mounted in face to face contact with a support plate, perforated with a plurality of apertures arranged in a predetermined pattern to permit passage of fluid through the plate, the apertures defining imperforate zones there between, the fabric being knitted or woven to have a surface defined by a plurality of parallel ribs in face to face contact with the support plate, each pair of adjacent ribs defining therebetween opposed sides of a fluid channel which communicates with a number of said apertures and said imperforate zones, the ribs being knitted or woven to be sufficiently non-compressible in order to resist collapse of said fluid channels during compression of the cementitious product within said mould.

Abstract: An adsorptive separation device is disclosed having at least one spiral wound adsorption membrane situated around the periphery of a core mandrel wherein the flow is radial from a feed plenum situated between the core mandrel and the membrane, through the membrane to a permeate plenum located between the membrane and a housing for both the core mandrel and the spiral wound membrane. An array of such separation devices is also disclosed showing connections in parallel, in series, in both parallel and in series and in tandem.

Abstract: Supported separation membranes are disclosed wherein the permselective membrane is integral with a polymeric support of non-woven fibers having a particular air permeability, the integral membranes exhibiting far superior lifetimes and retention capability, especially for microorganisms.

Abstract: The blood filter cartridge of the invention can be used as a sample cup of an analyzer without sucking bubbles, which comprises a blood filtering material, a holder containing the blood filtering material and having a blood inlet and a filtrate outlet, and a filtrate receiver for receiving filtrate discharged from the filtrate outlet, the filtrate receiver has an upper end having a difference in height or structure for returning the filtrate from the upper end of the filtrate receiver to the filtrate outlet.

Abstract: Described is a method of isolating cell components, such as nucleic acids, from natural sources by filtering a sample of the digested natural sources such as cells or cell fragments. The method is characterized in that the sample is passed through a filter, the pore size of which decreases in the direction of flow of the sample through the filter.

Abstract: A screen assembly for a vibratory separator has been invented, which, in certain aspects, has at least two ridge-valley series of screening material with a plurality of alternating ridges and valleys of screening material, and at least one flat area of screening material adjacent at least one of the ridge-valley series.

Abstract: A leukocyte-removing filter medium which comprises a matrix and ultra-fine fibers having a fiber diameter of less than 1.0 &mgr;m and not less than 0.01 &mgr;m which contains ultra-fine fibers in an amount of less than 50 wt % and not less than 0.1 wt %, the degree of curvature of the ultra-fine fibers being 1.2 or more, and/or the ultra-fine fibers form pores having a roundness of 1.7 or less.

Abstract: A filter is provided for filtering contaminants from a fluid passing through the filter. The filter comprises a silicon substrate having opposing first and second surfaces and a passage extending through it. A first etch resistant material layer is formed on the first substrate surface and includes at least one opening which extends through the first layer and communicates with the substrate passage. A second etch resistant material layer is formed on the second substrate surface and includes a plurality of pores which extend through the second layer and communicate with the substrate passage. The second layer defines a filter layer which filters contaminants from fluid passing through the second layer. A process for forming the filter is also provided.

Abstract: A storm sewer filtering apparatus is provided having a filter bag forming a rectangularly shaped substrate retaining volume. A flat bottom surface remains at the bottom of the filter bag and forms the majority of the filtering surface. Geotextile fabric forms a filtering media and incorporates a plurality of woven webbing reinforcement straps to provide additional strength to the finished filter bag. The woven webbing is affixed to the geotextile filtering media by conventional stitching methods, and extends beyond the edge of the respective sidewall for attachment to a drain grate. Rigidly affixed to each terminal end of the attachment strap is a retaining block that is linearly elongated and made of a rigid material, such as wood, metal, or hard plastic.

Abstract: The present invention provides a plasma separation filter capable of easily, speedily and safely separating plasma from a small quantity of blood without damaging blood cell components in the blood. The plasma retains the same protein concentration as in the blood. The present invention also provides a method using such a filter and an apparatus comprising such a filter. The filter of the present invention comprises a micro fiber medium formed of micro fibers with an average hydraulic radius of 0.5 &mgr;m to 3.0 &mgr;m. Such a micro fiber medium is placed in a container having an inlet and an outlet so that a ratio (L/D) of a blood flow passage length (L) to a blood flow passage diameter (D) is 0.15 to 6. The present invention provides such a filter, a plasma separation method using the filter, and a plasma separation apparatus comprising the filter. The present invention can significantly contribute to promote the automation and enhance speediness and safety in clinical tests.

Abstract: A screen for a vibratory separator for screening fluid with material entrained therein introduced on the screen, the screen having, in certain aspects, a plurality of warp wires and a plurality of shute wires, the warp wires interwoven with the shute wires, the plurality of warp wires including a plurality of first warp wires and a plurality of spaced-apart support wires, the support wires having a diameter greater than a diameter of the warp wires. In another aspect, a screen for a vibratory separator for screening fluid with material entrained therein introduced on the screen, the screen having a plurality of warp wires and a plurality of shute wires, the warp wires interwoven with the shute wires, the plurality of shute wires including a plurality of first shute wires and a plurality of spaced-apart support wires, the support wires having a diameter greater than a diameter of the first shute wires.

Abstract: This invention provides a blood filter unit capable of obtaining a necessary volume of a plasma or serum sample from blood to be assayed easily at any place, which comprises a blood filtering material and a holder accommodating the blood filtering material and having a nozzle for sucking blood and a filtrate outlet, and the inside of the holder being kept reduced pressure conditions.

Abstract: Filter cartridge assemblies are provided with a generally cylindrical filter medium which defines a cylindrically shaped core space, and a pair of end caps. A threaded base member having detent projections receives at least one of the end caps, which itself is annular and has an interior cylindrical surface defining an interior space in alignment with the core space. The interior space is also provided with interrupted threads defining detent spaces. In use, therefore, the lower end cap may be threadably coupled with the threaded base member such that the detent projections are seated in respective ones of the detent, thereby minimizing the unintended threaded uncoupling therebetween. In another aspect, the filter cartridge is most preferably “coreless” and is capable of being sleeved over a permanent, reusable perforated core element. However, the core element is removably insertable within a base member to which the filter cartridge may be coupled.

Abstract: An oil suction filter having an enclosed housing with a base surface and an oil intake opening, a top surface with an oil discharge opening, and a filter usually in the form of a filter cloth in the housing between the intake opening and the outlet. In one form, an oil diverting device at least partially surrounds the oil intake opening. In another form, an oil flow diverting device is provided at either or both of the oil intake opening and the oil outlet. In another form, an oil filter cloth has various densities, thicknesses or layers that control the flow. All the foregoing is for the purpose of minimizing formation of large air bubbles passing through the suction filter. Further, beads in the housing may keep the filter cloth off the base surface.

Abstract: Filter for removal of leucocytes is provided, wherein the filter is coated with a natural polymer of chitosan which has a good blood compatibility and no side effect in human body on an ultrafine non-woven fabric. This blood filter provides a high removal rate of leucocytes as well as good recovery of platelets and red blood cells due to secondary filtration through electrostatic power between a leucocyte and a cationic residue provided by chitosan on the surface of the non-woven fabric.

Abstract: A method for removing tumor cells from tumor cell-contaminated stem cell products is disclosed. One embodiment of the method relies on an in-line filtration device that includes a tumor cell reduction filter means, preferably comprised of one or more tumor cell reduction filter pads. The tumor cell reduction filter means provides at least a ten-fold reduction in tumor cells while allowing for at least a 30% recovery of stem cells in a filtered stem cell product.

Abstract: The blood filter unit of the invention is composed of a blood filtering material made of glass fiber filter and microporous membrane and a holder having a blood inlet and a filtrate outlet. The holder accommodates the blood filtering material so that the microporous membrane is located on the filtrate outlet side, provides a space between the blood filtering material and the filtrate outlet, and provides a means for preventing adhesion of the blood filtering material on the filtrate outlet side. By using the blood filter unit, a necessary volume of plasma or serum for analysis can be separated surely, irrespective of hematocrit value of the blood.

Abstract: A method for purifying conventionally treated blood plasma to remove substantially all residual leukocytes while maintaining useful flow rates for medically useful amounts of plasma utilizes a disposable, heat-sterilizable filter employing one or more depth-type prefilters and at least one intermediate hydrophilic microporous membrane followed by at least one final hydrophilic microporous membrane having a smaller pore size than the intermediate membrane within a common housing. The purified plasma is preferably subjected to chemical treatment to destroy infectious agents such as hepatitis and HIV.

Abstract: Air filter elements with primary filter medias have foam pre-cleaners with an increased surface area provided by an upstream face which has peaks and valleys. In one embodiment, the peaks and valleys are defined by parallel ribs. If the filter element is a panel-type filter element having a pleated primary filter media, then, in accordance with one embodiment, the pre-cleaner is secured to the primary filter media by adhesive deposits on the peaks of the primary filter media. If the filter element is annular, the pre-cleaner is also annular and is slid axially over a perforated sleeve or screen on the primary filter media and held thereon by friction. By having the upstream surface of the foam pre-cleaner configured in peaks and valleys, the surface area of the upstream surface is increased substantially, which improves the capacity, efficiency and life of the filter element.

Abstract: The invention relates to a filter element for a fluid filter incorporating a web of pleated filtering material that is formed into a circumferentially closed cylindrical filter body, which is coaxially supported by a perforate rigid tube and the axial ends of which are sealingly inserted into corresponding annular receiving cavities provided in a rigid bottom end cap at one end and in a rigid annular end cap at the opposite end of the filter body. The cylindrical filter body has its terminal edges embedded in separate sealing rings of a flexible type of rubber or similar elastomeric material and the filter body is sealingly clamped with the sealing rings, and together with the supporting tube, removably between the rigid bottom end cap and annular end cap, respectively.

Abstract: A storm sewer catch basin filter includes a frame having a plurality of radially extending arms, each arm having an end. The catch basin filter further includes an edge piece fixed to the end of each of the arms and be engageable with a lip in a storm sewer catch basin. Furthermore, the catch basin filter includes a filter bag, supported from the edge pieces, and wherein the filter bag has an open top for receiving water entering the storm sewer catch basin, so that the water is filtered as it passes through the filter bag.

Abstract: A combination filter element comprising a bundle of hollow microporous fibers housed within an extruded carbon block, wherein the carbon block is fabricated to balance particle retention capacity against absorption capacity to provide a composite filter with desirable pressure drop, filter life, and particulate and chemical contamination reduction, and a filtration device, in which combination filter element may be employed, having a base portion including a sump which has an inlet and an outlet and a base which has a reception port for receiving the filter element.

Abstract: A method of separating cells from blood by using a filter apparatus having first and second ports and a filter member therebetween having a changeable porosity. The filter member includes a stack of porous polymer sheets that preferably has a gradient of a physical or chemical characteristic in the direction of stacking. This can include a gradient in porosity, hydrophilicity or zeta potential. In a first step, blood is filtered through the apparatus when the filter member is set to a compressive state having a first porosity capable of capturing the objective cells. In a later step, the filter member is then set to a non-compressive state having a second porosity, higher than the first, for recovering the objective cells. The change in porosity results from the enlargement or reduction of the diameter of the pores of the filter member. The method can also include washing the filter member when the member is set to a porosity that is higher than the first porosity but lower than the second porosity.

Abstract: A sealing ring for use in connection with a filter bag assembly of a filter is disclosed. The sealing ring includes an annular body having an outer annular wall projecting from the body. The outer wall is flexible such that it can engage an adjacent surface of the filter in a liquid-tight manner for forming a seal between the surface and the sealing ring.

Abstract: A dynamic filter system includes a dynamic filter assembly including one or more filter elements and one or more members disposed within a housing. The filter elements and the members are interleaved and arranged to rotate with respect to one another. The dynamic filter assembly preferably includes one or more mechanisms to prevent preferential fouling.

Abstract: A filter has a first filter layer made of TiO.sub.2 of Ti.sub.4 O.sub.7 particles deposited on a second filter layer by stainless steel particles. The first layer has a smaller pore size than the second layer. The construction of the filter, the relative thicknesses of the layers and the resistances thereof to movement therethrough of electrolytically generated gas located between the two layers when the filter is permeated with liquid are such that the gas reaches the upstream side of the filter before the downstream side. In one embodiment stainless steel particles are sintered and rolled with a textured roller before ceramic particles are applied and rolled. An intermediate layer of metal particle peaks and ceramic filled troughs is thus provided which has high tortuosity. The resistance to flow at the metal/ceramic interface can be increased by electrodeposition of metal there.

Abstract: A papermakers' screen basket for pressure screening of papermaking stock or for pressure filtering is formed with a support core formed with honeycomb like cells that extend radially in the direction of flow through the screen basket, and a thin covering having screening openings therethrough is supported on the inlet surface of the honeycomb cell core. The core is formed by rolling a flat section of core into the shape of a cylinder and welding the abutting ends to form a complete cylinder and then attaching a perforated or a mesh sheet-like metal covering against the core inlet surface, in which the thin sheet metal covering defines small openings, such as slots or apertures, leading into the honeycomb core, and is welded in place.

Abstract: A filter cartridge that includes a track etched membrane sealed therein in a leak-free manner, and a method for making the cartridge. The filter cartridge has a bubble point that is at least 50% of the bubble point of the track etched membrane. In one embodiment, the method includes disposing the track etched membrane below a heat source and orienting the membrane so that it melts back on itself, and then allowing the membrane to cool to form a leak-free seal.

Abstract: A filter element for a pressure filter where a substantially horizontal wall (3) divides the interior of a pressure vessel into a lower inlet compartment (5) and an upper outlet compartment (6). A filter element (20) having a filter medium (40) is suspended from the wall (3) such that the filtering takes place from the inlet compartment (5) through the filter element (20) up to the outlet compartment (6). A corrugated sheet (22) is provided which defines a plurality of substantially vertically extending channels (45) and (42). Each first channel (45) is open the inlet compartment (5) with the filter medium (40) covering the first channels (45) with the upper end of the first channels (45) being closed and the lower end of the first channels (45) being open at (43). The second channels (42) being formed on an inner side of the corrugated sheet (22) with an open bottom end and an upper end communicating with the outlet compartment (6).

Abstract: A filter apparatus (10) which dissipates static charge from fluid flowing through the apparatus has a filter housing (12) enclosing a filter element (14). The filter element includes a tubular filter media assembly (15) which incorporates a conductive structure to draw off static charge in fluid passing through the media. The tubular filter media assembly comprises an outer steel mesh support layer (24); a first intermediate layer (25) of a filtration media; a second intermediate layer (26) of a carbon material, e.g., stainless steel, nickel or carbon fiber mesh, mat or matrix; and an inner steel mesh support layer (27). The filter media assembly is pleated and disposed around a central perforated conductive tube (16). The filter media is electrically connected at one or both ends through conductive adhesive or epoxy to at least one conductive end cap (20, 22). The conductive end cap has a central opening (33, 34), and receives a portion of the grounded filter housing (50, 52), for example, an inlet tube.

Abstract: A filter cartridge assembly includes a filter cartridge having a generally cylindrical filter medium which defines a cylindrically shaped core space, and a pair of end caps fixed to opposite ends of the filter medium. Most preferably, the filter cartridge is "coreless" in that it is not provided with an integral support core structure. At least one of the end caps (e.g., the proximal end cap) is annular and has an interior cylindrical surface defining an interior space in alignment with the core space. A truncated generally conically shaped seal skirt is operatively associated with the annular end caps. The filter cartridge is sleeved over reusable support core structure which includes a base having a truncated conically shaped seal skirt, and a tubular perforated rigid core element fixed at one end to the base. The annular end-cap and the base of the support core structure are removably mechanically coupled to one another, most preferably by being threadably interconnected.

Abstract: A drain filtering system is disclosed, comprising a filter placed within a basket which is suspended from frame positioned underneath a drain grate atop the inlet to a storm drain. The filter is constructed from materials which filter out heavy metals and hydrocarbons from the water passing through. The filter also has overflow outlets to prevent back-up of storm water during periods of heavy rain. The basket is constructed from a corrosion resistant material, preferably high density polyethylene which can withstand the extreme pressures exerted by waste and water collected within the filter.

Abstract: A fluid filter includes a first batting of high loft, non-woven, fibrous fluid-permeable material with a plurality of openings formed through the thickness thereof across the length and width of the batting. A second layer of high loft, non-woven, fluid-permeable fibrous batting is attached to the first layer and extends across the entire length and width of the first layer. Preferably, the first and second layers are adhered together to form a single integral fluid filter. In the preferred form of the invention, the openings in the first batting have side walls which are perpendicular to the upper surface of the batting, such that fluid flow impacts on the upper surface of the batting, rather than directly impacting on the side walls.

Abstract: A novel filter assembly for a drainage system stormwater catch basin is provided with spaced-apart open frame elements that are joined to and carry a singular mesh fabric filter element, and with manually pivotable support leg elements that permit the assembly to be collapsed for subsequent transportation, storage, or refurbishing.

Abstract: A new type of non-tensioned shaker filter for a shaker machine. The shaker filter is comprised of layers of wire cloth that are bonded together without a rigid backing and are corrugated. Left and right side edges are provided on the left and right sides of the filter, respectively, in order to protect the user from injury from sharp edges and to seal the filter to ledge provided on a non-tensioned means for securing the filter to the shaker. Front and back edges of the filter are provided with front and back lips respectively on a bottom side of the filter in order to protect the user from injury from sharp edges and to seal the filter to the non-tensioned means for securing the filter to the shaker.

Abstract: A screening screen assembly for a vibratory screening machine including an apertured plate, and a subassembly of an undulating support screen and fine screening screen and finer screening screen bonded to each other by a fused plastic grid and bonded to the apertured plate. A method of fabricating a screening screen assembly for a vibratory screening machine including the steps of providing a support screen, superimposing a plastic grid onto the support screen, superimposing a finer screening screen onto the fine screening screen, applying heat and pressure to the superimposed screens to fuse the plastic grid and thereby form a flat bonded laminate subassembly by causing the fused plastic grid to permeate the fine screen and the finer screen and the support screen, forming the bonded laminate subassembly into an undulating shape, providing an apertured plate, and bonding the undulating bonded subassembly to the apertured plate.

Abstract: A multiple tube filter made of at least one perforated filter element (15), wherein the outside of the filter element (15) has spirally circulating grooves (2), and the surface between grooves (2) is preferably arched outward in the form of a segment of a circle.

Abstract: Process and device intended for ultrafiltration of particles contained in fluids. The fluids are passed through at least one filtering barrier made from a source rock with micropores below a few hundred Angstroms in diameter. These rock samples are available in good supply for example when drilling through reservoirs containing hydrocarbons. The filtering device comprises a housing (1) containing at least one thin disk (5) cut in a source rock, through which fluid is passed. This disk withstands high pressures and temperatures well, and it can be regenerated after use by means of a thermal process. The process and device can be applied for filtering of colloidal particles such as resins or asphaltenes in petroleum fluids for example.

Abstract: A filter arrangement with a cellular structure in which a plurality of filter chambers extend in the direction of the medium to be filtered. There is a filter cloth or fabric attached to each of the two sides of a cell frame which closes the filter chambers on both sides. The filter chambers are each provided with a filling of predominantly active charcoal granules. To achieve a simple and advantageous structure of the filter arrangement, the cellular structure is in the form of a rectangular cell frame each with rectangular filter chambers, preferably made of synthetic resin. Appropriate, right-angled partition walls inside the cell frame and the installation of reinforcement members can result in filter chambers of optimum size.