Abstract: A modular filter assembly is described comprising a filter stack having a plurality of filter sheets and a plurality of filter support plates each having a perimeter and an internal filter flow passageway portion. The filter sheets are sandwiched between surrounding filter support plates forming the stack and the filter flow passageway portions of the plates and filter sheets are aligned to form a filter flow passageway extending from the top to the bottom of the stack. The filter stack has engaging means capable of keeping the filter support plates together while minimized top to bottom dimension because it is not necessary to use external clamps for keeping the support plates together. Also described are support plates for modular filters and a method for forming a modular filter assembly.

Abstract: Composite semipermeable membranes comprising porous adsorptive material supported by a porous substrate are disclosed for use in a process for the separation of multicomponent gas mixtures. In the process, one or more primary components adsorb within the pores of the adsorptive material and diffuse by surface flow through the membrane to yield a permeate stream enriched in one or more of the primary components. Methods for making the composite membranes are described.

Abstract: A filter and method for applying differential levels of active ingredient materials to specific areas of filters, such as the filter paper used to make disposable vacuum cleaner bags, so as to cause the effluent such as air which has passed through such filters to sustainably act as a dispersing agent for such filter-impregnated active ingredients as may condition the effluent which has passed through the filter in ways that are desirable to the user of the filter. The active ingredients are unevenly distributed on the filter substrate in a pattern determined by predicted changing flow rate patterns through the area of the substrate during intervals of increasing accumulation of particulate matter against the filter and effective to maximally sustain dispersion of active ingredient during such intervals.

Abstract: A method for manufacturing a filter cartridge by polymerization of a polyethylene hydrocarbon with granular elements are set forth. The method involves the preparation of a mixture comprising the hydrocarbon and the granular elements, then introduction of the mixture into a mold which is formed by a first porous wall and a second porous wall, these walls being connected to a jacket, the introduction of the mold in an oven so as to raise the temperature of the mixture and by a thermal polymerization reaction to transform the hydrocarbon into a material binding the granular elements of the mixture, the assembly of the material and granular elements then forming a cartridge, and injection of a chemically inert gaseous composition into the mold through one of the walls to impart fluid permeability to the cartridge.

Abstract: A method of manufacturing a filter element comprises the steps of mechanically crushing two grades or more of a heat resistive synthetic resin material, the grades having different melt flow indices, respectively, the heat resistive synthetic resin material being selected from the group consisting of polysulfone, polyethersulfone and polyphenylenesulfide or containing said selected heat resistive synthetic resin as a main constituent, mixing them with one grade of them being 20 to 80 wt %, sintering the mixture in a metal mold at a melt temperature thereof plus or minus 10.degree. C. when the mixture is crystalline resin or at a temperature in a range from glass transition temperature thereof up to the glass transition temperature plus 40.degree. C.

Abstract: A filter plate (1) is described on which a filter cloth (4) is disposed across the whole top side and glued or welded to the outer sides, and which is used for filtering off particles from a liquid. The plate has a large number of apertures (2), each individual aperture area being at most 2.25 cm.sup.2. The total free open area of the plate is 70-90% of the total plate area and the thickness of the plate is at least 5 mm.

Abstract: A ceramic filter for a dust-containing gas, which comprises a filter base having an average pore size of from 10 to 100 .mu.m, with the pore size ratio at positions of 75 vol % and 25 vol % of the accumulated pore size distribution being at least 1.3, and a filter layer having an average pore size of from 0.2 to 10 .mu.m fixed at least to the filtering side surface of the filter base so that the filter layer fills the pores open on the surface of the filter base.

Abstract: The present invention provides a surface modified polymeric gas separation membrane having improved selectivity, particularly for oxygen/nitrogen gas mixtures, prepared by forming a membrane of a polymer having the structural formula ##STR1## wherein R and R" can be the same or different linear, branched or cyclic alkyl group having one to twelve carbon atoms, or R can be H, with the proviso that both R and R" cannot be methyl, and n is at least 100, and treating the surface of the membrane with a fluoro-oxidizing agent at conditions sufficient to fluoro-oxidize the membrane surface.

Abstract: A fluid filter and a method of constructing a fluid filter which will independently retain itself in a fluid passageway includes a sheet of filter media and a retainer which is attachable to one side of the filter media. The retainer may be sized to frictionally engage the walls of the fluid passageway or may be of a resilient material which allows the retainer to resiliently engage the walls of the passageway. The retainer is attached around only the periphery of the filter media with the central portion of the filter media being free with the respect to the retainer. The filter media has flexible edges which extend beyond the retainer to seal the passageway so that all fluid flowing through the passageway will flow through the filter media.

Abstract: An air filter comprising a sheet of filter material folded in a zig-zag configuration. A hardenable material is dispensed in a flowable state onto the sheet. The hardenable material has a varying thickness such that upon hardening, it holds the folds of the sheet apart in a selected orientation. The hardenable material may comprise glue to also secure the folds together. An air penetrable sheet can be secured to the fold edges at one or both sides of the filter.

Abstract: A composite filter element for filtering hot gasses is made up of a porous ceramic core to which a porous ceramic, thin outer layer is integrally bonded. The outer layer has a mean pore size which is at least several times smaller than the mean pore size of the substrate and the substrate is at least several times thicker than is the outer layer. The outer layer and the substrate are preferably formed of the same material or of two different materials having essentially the same coefficient of thermal expansion.

Abstract: A filter useful as a cigarette smoke filter is made by convergingly passing a flat restrained meltblown web successively through a heated zone and a trumpet to form a roving. The roving may be processed to make filters. The process results in stretch orientation of longitudinal fibers and bulking due to cross fibers. Primary and secondary pleats formed in the web are bundled into a cylindrical roving. The pleats add bulking to the web and provide fluid permeability through the filter.

Abstract: The end caps of a filter element are formed on the element by dispensing a photo-initiated polymer in a transparent mold, setting the end of the filter media array in the mold, exposing the mold to ultraviolet light for a time sufficient to cure the polymer, and then stripping the mold from the finished end cap. Accordingly, the time of 60-75 seconds required to cure prior art Plastisol end caps is reduced to a few seconds necessary to cure the end caps made from the photo-initiated polymer. The end caps have been designed with reinforcing ribs to minimize the amount of polymer required while still maintaining necessary hoop strength to retain the media in place.

Abstract: The invention includes a filter element (10) having a pair of end caps (12) with pleated, corrugated filter media (14) spanning therebetween. The filter media (14) is sealed or potted into the end caps (12) with a potting material ( b 16). To ensure substantially uniform penetration of the plates of the media (14) by the potting material (16), the edges of the media (14) are configued to eliminate "linear check valve" action between pleats. Several edge patterns can be used to minimize the formation of linear check valves, including a saw tooth pattern; sine wave pattern; vertical edge corrugations; flat edge regions; and saw kerfs in the edges of the media.

Abstract: A method and an apparatus are provided for securing a bed of charcoal under pressure in a plastic material housing in the manufacture of charcoal filter canisters for gas masks. The bed of particulate charcoal is placed in the housing and covered with a retainer. A compactor is placed on the retainer and loaded to produce the desired compaction of the charcoal. An ultrasonic welder is then used to secure the retainer in place for one embodiment, a spring-loaded compactor is placed on top of the retainer and an ultrasonic nodal horn is placed over the compactor. The horn presses the compactor against the retainer with the necessary compressing force to compress the charcoal bed, while at the same time producing an ultrasonic weld around the periphery of the housing, welding the retainer in place. The compactor seats on a nodal point of the horn, so that ultrasonic vibrations are not transmitted from the horn through the compactor to the charcoal bed.

Abstract: Process for the production of filters whose active filtering part is made up of a folded filter material web, preferably made from paper, which folded web is delimited in the process by side edges at which the folds terminate, and end edges at which a first or last fold is located, so that in this way filter units (49) are formed. The filter units (49) are produced in an automatized process in which the filter material web is creased and pushed together to form the folds. The spacings between the folds are maintained constant by means of a screw element with threads pushing down between the folds and forming spacing elements between these. The screw element is rotataed during forward movement of the folded web. Glue-coated strips are pressed onto the said side edges of the web, so that the ends of the folds are covered over by the strips.

Abstract: A filter arrangement is provided which includes preferred fluid sealing between a top plate thereof and a housing. Generally, the filter arrangement includes a housing, a top plate and an internal filter. The top plate encloses an end of the housing, retaining the filter therein and directing fluid flow appropriately across the filter. Engagement between the housing and the top plate is such that a gasket may be used to provide sealing of an operable combination of the filter arrangement with an associated filter head, with respect to flow space between the housing and top plate by means of a simple gasket position externally of the filter arrangement. Several embodiments have shown, and in at least one the housing edge terminates in a groove in the top plate, in which a sealing gasket may be positioned. Positive engagement between the top plate and the housing is provided by a variety of projection arrangements.

Abstract: A ceramic filter element for filtering hot gasses is manufactured by first forming a skeletal member made up of randomly disposed ceramic fibers by pulling an aqueous solution of the fibers and a liquid binder onto a mandrel and then heat treating the member to dry the binder. The dried member is then coated with alumina gel, colloidal aluminum or colloidal silica and heat treated at a temperature within the range of 1700 degrees F. to 2300 degrees F. to dry the coating and increase the resistance of the coating to corrosion by hot gasses.

Abstract: Laminated composite structures for use in making fluid filters are disclosed. Such structures comprise (a) a densified high loft layer of powder bonded nonwoven fabric, rebulkable by heating, laminated to (b) a filter media or element that supplies stiffness to the laminate. Also disclosed are methods of making fluid filters, e.g., ones used to filter inlet air for internal combustion engines, from such laminates, and fluid filters containing such laminates in which the nonwoven layer has been rebulked by heating.

Abstract: A construction of filter sock which has a panel (1) with two leaves (2,3) of unequal width such that when folded along a foldline (4) the leaves form a double leaf panel with a projecting side (9). The side (9) is folded back along a second fold line (11) over the free side (6) of leaf (2). The sides (6,9) and leaf (2) are secured together by an overlock stitching (13) to form a tube (12). The invention provides a method of making the filter sock.

Abstract: A fiber bed element and process for utilizing such element for removing and collecting small particles of liquids or soluble solids from a gas stream, the element formed of one or more layers of pin-punched fiber supported by an appropriate supporting structure, the fiber layers being subjected to pressure to achieve a selected density and the punched holes functioning to create drainage paths through which liquids may drain. The fiber layer density and fiber size is maintained uniform throughout the element so that the pressure drop of the saturated filter bed element will be between 1.1 and 3.0 times the pressure drop of the dry filter bed as originally constructed and before use.

Abstract: The present invention relates, by way of a novel industrial product, to a filter for gaseous fluid, which contains a lyophilized and compressed filter element in the form of a porous layer.

Abstract: A unitary injection molded filter is disclosed which includes a rigid frame of resin material to provide a rigid shape to the filter, and at least one screen of non-woven sheet resin material suspended on the frame and having formed therethrough a plurality of holes extending between the opposed side surfaces of the screen so as to form fluid passages therethrough. Each screen is integrally molded simultaneously with the frame.

Abstract: A cell-type filter cartridge is disclosed having netting thereon, as well as a method for producing same. Briefly stated, the surface area of filter material exposed to unfiltered fluid has disposed thereon a netting thereby preventing flaking, cracking and the like of filter media during backflow or cleaning operations. The netting is secured to the cell by a molded circumferential retainer and a circumferential centrally disposed ring.

Abstract: A flexible filter bag, the filter element of which is seamless and avoids prior leakage problems, is made by wrapping a flexible, preferably perforated, filtering fabric and a flexible nonfiltering transport material together onto a cylindrical mandrel to provide a tube. A thin metal ring is fitted into the tube, and the portion of the filtering fabric which extends beyond the edge of the transport material is folded inwardly around the ring to provide a cuff. A sleeve of a length about twice that of the tube is inserted into and pulled over the tube until the free ends of the sleeve are approximately coterminous with the ring-free end of the tube. The free ends of the sleeve and tube are gathered in the manner of a sausage casing and then subjected to pressure to form a seal, but the convolutions of the transport material terminate just short of the seal so as to avoid bunching at the seal.

Abstract: Muffler apparatus for reducing both sound and particulates from exhaust gases from an engine. The apparatus includes resonating chambers, flow distribution structure and a cellular ceramic core filter module. Filter regeneration mechanism includes a heating element for heating the carbon on the inlet end of the ceramic core to combustion temperature. Particulate ignition resulting in regeneration occurs when combustion air is provided; in alternate embodiments, combustion air first flows through a preheater system. A processor unit with particular logic controls the apparatus.

Abstract: A tubular filter element for liquid filters comprises a perforated support pipe. Disposed around the inside of the support pipe is a tubular filter layer which comprises a folded sheet of filter material. Within each end of the filter element a spring washer is disposed for biasing the end of the tubular filter layer outwardly against the inside of the support pipe. In this pre-biased state, the ends of the filter element are joined to disks by means of a hardenable casting material.

Abstract: Muffler apparatus for reducing both sound and particulates from exhaust gases from an engine. The apparatus includes resonating chambers, flow distribution structure and a cellular ceramic core filter module. Filter regeneration mechanism includes a heating element for heating the carbon on the inlet end of the ceramic core to combustion temperature. Particulate ignition resulting in regeneration occurs when combustion air is provided; in alternate embodiments, combustion air first flows through a preheater system. A processor unit with particular logic controls the apparatus.

Abstract: A spirally wound filter cartridge and a method of making the same in which the cartridge includes an elongated, centrally disposed tube or mandrel, and a sheet of filtration material spirally wound around the tube such that the cartridge has a tapered configuration with a first end of the cartridge being greater in diameter than the second end. The present invention also relates to a filtration device having a filter cartridge housing adapted to receive the above mentioned tapered filter cartridge.

Abstract: A filter bag enclosure for containing a laboratory animal and a carrier therefor during transportation is provided with lateral and top seals which prevent gaseous communication with the laboratory animal therewithin except through the filter medium which forms the lateral sides of the filter bag. In accordance with the invention, the lateral edges of the filter bag are sealingly joined to one another by the application of acoustic energy. A length of sealing material, which may be polyethylene, is advantageously interposed between the edges prior to the application of the acoustic energy so as to enhance the reliability of the lateral seals. The top portion of the filter bag is provided with polyethylene strips joined thereto, illustratively by the use of ultrasonic acoustic energy. After the laboratory animal and its carrier is installed inside of the filter bag, the filter bag may be closed by conventional heat sealing of the polyethylene top strips.

Abstract: A filter for removing dusts from fluids, which comprises fibers bonded each other with a binder and/or hot-pressed, having a fiber density of 0.01 to 0.1 at the side of inflow of fluid to be treated and a fiber density of 0.05 to 0.5 at the side of outflow of the fluid with a continuous fiber density gradient and having a uniform distribution of fiber material in direction of thickness, and a process for the production thereof. The filter is particularly useful as an air filter for automobiles or air conditioner.

Abstract: An air filter medium, in which a dust-collecting layer of glass fibers of a diameter necessary for obtaining a desired dust-collecting efficiency is formed on a supporting fiber layer of low dust-collecting efficiency and low pressure drop to a sufficient thickness to obtain a desired dust-collecting efficiency and a desired pressure drop of the air filter medium.

Abstract: A filter element and method for making it include the steps of providing a pleated paper filtering media and providing a batt-like filtering media containing thermoplastic fibers which is slightly larger than the pleated paper filtering media. A ring-shaped die is used in a press to apply heat and pressure to the edges of the batt-like filtering media while accommodating the rest of the batt-like filtering media in the aperture of the die. Accordingly, a stiffened wall is provided which circumscribes the pleated paper filtering media. The pleated paper filtering media is attached to the stiffened, fluid-impermeable wall to provide a fluid-impermeable seal therebetween. A perimetrically-extending flange gasket is simultaneously formed around the edge of the batt-like media, so that the latter can be sealingly engaged in an air cleaner housing.

Abstract: An automatic assembly machine for assembling a pleated filter material and a perforate hollow core member includes a wrapping station, an adhesive application station and a clamping station. A conveyor moves the filter material and the core member together as a unit through the wrapping station and the adhesive application station. The clamping station both clamps the seam to which adhesive has been applied for a period of time sufficient to permit curing of the adhesive joint, and simultaneously conveys the filter material and core member assembly. A method for assembling a pleated filter material and a perforate hollow core member includes the steps of conveying both the filter material and the hollow core member to a point where they come in mutual contact, supporting one of the members on the other, and simultaneously conveying the filter material and core member sequentially through a wrapping station and an adhesive application station.

Abstract: A non-woven felt suitable for use as a filter comprised of poly(tetrafluoroethylene) and glass fibers hydraulically entangled to a supporting scrim and a process for making said felt are disclosed. The scrim is made from high temperature and chemically resistant materials.

Abstract: A filter for separating constituent components of fluids includes a plural-layer sheet-like member which is multiply pleated to provide layers of the same or different porosity or to provide structural support layers for pleating a soft or membrane-like filter layer. The multiple layers may be pre-joined or delivered from individual locations to a pneumatic conveyor passage of predetermined cross-section through which the adjacent layers are conveyed by a conveyor gas. The layers are crimped to form pleats by withdrawing the material at a lower linear speed than that at which it is supplied to the passage. Pleating is facilitated by venting the conveyor gas at a passage section of enlarged cross-section. The pleating material is subjected to a hot gas, such as steam, and then cooled by a cooling gas to effect bonding of the layers in the pleated state.

Abstract: The present invention provides a filter element made wholly of fluorocarbons resin, comprising as essential elements a filter material produced by folding a sandwich-form sheet comprising a filter membrane made of a fluorocarbon resin and net supporters made of a thermoplastic fluorocarbon resin superimposed on the both surfaces thereof into a pleat form and liquid-tightly welding the edge parts of the both sides of the pleated sheet, sealed end parts produced by embedding the both end parts of said filter material except the central openings into a thermoplastic fluorocarbon resin to force the resin into the pleats, whereby the both end parts are each integrally and tightly welded, and fluorocarbon resin caps welded liquid-tightly with said sealed end parts, and production thereof.

Abstract: The present invention relates to a continuous method for manufacturing an electret filter medium from dielectric material having an open or porous structure, said method comprising the steps of continuously feeding a web of dielectric material with a substantially closed dielectric foil adjacent to at least one major face thereof into a corona discharge device, reducing the thickness of the web of dielectric material and charging the web of reduced thickness dielectric material by means of a corona discharge and to apparatus for carrying out said method.

Abstract: This invention is directed to means for expediting the fabrication of selectively-manifolded honeycomb structures for use as fluid filter elements. The method comprises the use of flexible masks which are properly aligned to the end faces of a honeycomb structure utilizing vibratory motion in conjunction with a locating wire. By varying the configuration of the masks, it is possible to fabricate a fluid filter element having a center zone which is selectively manifolded and an outer portion wherein at least the ends of the honeycomb structure cells are completely filled.

Abstract: A filter element comprises coaxial inner and outer relatively rigid, permeable cylinders (5, 8), each cylinder being circumferentially continuous and sandwiched between the two cylinders, a spirally-wound cylindrical filter structure comprising a plurality of layers of microporous non-woven fibrous material (9), each pair of adjacent layers being separated by a layer of strong, fluid-permeable, flexible support material (10), the filter structure being under substantially uniform radial compression over the whole of its area. The compression is preferably such as to compress the filter structure by from 25% to 45% of its original thickness, and materially increases the efficiency of filters incorporating the structure. A method of effecting the compression during manufacture is also described.

Abstract: A method for impregnating a bundle of sized glass fibers with a composition comprising a polytetrafluoroethylene resin, a film-forming acrylic resin, a thickening agent and a polyhydrolyzable organosilane having nonhydrolyzable amine functionality is described. The impregnated bundles are especially suited for at least the warp of fabrics for filtering entrained particulates from gases such as flue gases from the combustion of hydrocarbon fuels such as coal.

Abstract: A filter bag with removable ring and handle suitable for use with high pressure filter housings includes a two-piece ring which is assembled together with a filter bag without the need for stitching or welding and includes a handle as an integral part of one of the rings to facilitate removal of the filter bag from a filter housing.A method of assembling a filter bag with a removable ring and handle for removal of the filter from a filter housing is disclosed.

Abstract: The disclosure relates to a novel and highly superior filter media formed of random-laid, lignin-containing fibers, and to a process for manufacture of the filter media. The process involves selection of lignin-containing fiber source, having a lignin content of at least about 10% and thermomechanically pulping the fiber source under temperature/pressure conditions of 300.degree. F.-350.degree. F./50 psig-120 psig and a refiner energy utilization of about 8-35 HPD/ADT. The thermomechanically produced fibers are characterized by a high degree of stiffness, and an extremely smooth surface free of fine fibril formation and thus substantially non-self-bonding. An improved filter media is formed by a random lay-up of the lignin-containing fibers, typically with selected other pulp fibers having technical characteristics suitable for filter media utilization.

Abstract: A sintered, honeycomb structure having plugged cell ends is formed in a single sintering step by plugging the cell ends of a sinterable honeycomb structure with an appropriate material which, when heated to the sintering temperature of the structure and compared with any dimensional changes the structure undergoes during its sintering, provides a relative expansion of the plugs with respect to the structure of between about 1.5% and 7% and, preferably, between about 2 and 4%. Various exemplary batch mixtures are identified for fabricating solid particulate filter bodies from extruded ceramic substrates in which both the substrate and plugs sinter to primarily cordierite crystal phases at temperatures between about 1340.degree. C. and 1450.degree. C.

Abstract: The disclosure related in part to a novel and highly superior high bulk pulp formed of lignin-containing fibers, and to process conditions for manufacture of the pulp. The process involves selection of a lignin-containing fiber source, having a lignin content of at least about 10%, and thermomechanically pulping the fiber source under temperature/pressure conditions of 300.degree. F.-350.degree. F./50 psig-120 psig and a refiner energy utilization of about 8-35 HPT/ADT, using a double disc, counter rotating disc refiner. The thermomechanically produced fibers are characterized by a high degree of stiffness, and an extremely smooth surface, free of fine fibril formation and thus substantially non-self-bonding. The new pulp has a wide variety of specialty uses which are attractive in terms of both economics and technical performance, because of the exceptionally high bulk and other distinctive characteristics of the fiber.

Abstract: A pleated media filter element is disclosed which includes pleat spacers which are an integral structural part of the pleated media. The construction of the pleat spacers is accomplished by scoring on the unfolded media a continuous line pattern upon the portion of the media which, when folded, forms a pleat tip of the element. When the scored media is folded into pleats the patterns each define areas on the respective pleat tips which are integral structural parts of the media itself. The configuration of the pattern causes a portion of the media at the pleat tip to project transversely relative to the respective pleat, serving thereby as an integral spacer to space the pleat apart from the pleats on either side thereof.

Abstract: Air filter elements employing a block of deep pleated paper and methods of their construction. A preferred filter element comprises top and bottom end members both adapted for through passage of air and a first pair of side walls, a block of deep-pleated paper between the end members and the side walls, connections between adjacent edges of the end members and the side walls, at least two connections being hinged and at least one connection being interengaging elements, sealing structure comprising a second pair of side walls and at least one flange around one end member, the material of which structure rigidifies the connections and forms a seal with the pleated paper. The sealing structure is formed preferably from an elastomer which solidifies in situ.In a preferred method of construction the first side walls are hinged up from the bottom wall around the pleated paper block and connected at the top. The second side walls and end flanges are then formed of elastomeric material.

Abstract: A filter for cleaning exhaust gases emitted from a diesel engine is disclosed. The filter is composed of a cleaning portion formed of porous ceramic, through which the exhaust gases flow and in which carbon particulates in the exhaust gases are collected, and an outer wall portion formed of the same kind of material as that of the cleaning portion, which is formed around the cleaning portion so as to be integral therewith. The bulk density of the outer wall portion increases from the inner periphery thereof toward the outer periphery thereof so that the exhaust gases can be prevented from flowing out of the outer wall portion.

Abstract: The invention comprises solid particulate filter bodies having so-called "sloppy" plugging configurations in which clusters of mutually adjoining cell ends are plugged at the two end faces of a honeycomb structure such that the clusters at each end face adjoin or partially overlap one another and at least some of the cells of the structure are closed at both end faces while the remaining cells of the structure are closed at only one end face. Preferably "sloppy" plugging is accomplished by providing a pair of masks each having a plurality of opening extending therethrough which are sufficiently large to expose clusters of mutually adjoining cell ends and are positioned so as to partially overlap one another when the two masks are aligned opposing one another on opposite end faces of a honeycomb structure. A flowable plugging material charged through the masks plugs the clusters of cell ends at each end face.

Abstract: An apparatus for filtering solid particulates from fluid flows having a honeycomb filter body formed by a matrix of thin, interconnected porous walls which define inlet and outlet faces of the body and a plurality of hollow inlet and outlet cells each extending through the body from at least one of the inlet or outlet faces, the thin walls having internal interconnected open porosity sufficient to allow the fluid to travel completely across the thin walls in their narrower dimension and through the thin walls in their longer dimensions between the inlet and outlet cells and to prevent at least a significant portion of the solid particulate material carried by the fluid from passing either completely across or through the walls. Solid particulate filtering occurs on all thin wall surfaces of the inlet cells regardless of whether those thin walls are shared with adjoining inlet or outlet cells.