Hybrid height pleated filter element

Abstract

A cylindrical hollow filter element is provided comprising repeated segments, each segment comprising, in order: (a) a first group of three pleats (M1, M2, M3), having corresponding pleat heights (H1, H2, H3), wherein H1<H2<H3; (b) a first septum L1 having a pleat height LH1; (c) a second group of three pleats (M4, M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2, having a pleat height LH2; (e) inverted pleat W, having a pleat height WH; (f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1‑H6.

Description

7751161HYBRID HEIGHT PLEATED FILTER ELEMENTCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 759,655, filed February 18, 2025, which is incorporated by reference.BACKGROUND OF THE INVENTION

[0002] There is a need in the art for improved pleated filter elements.

[0003] The present invention provides for ameliorating at least some of the disadvantages of the prior art. These and other advantages of the present invention will be apparent from the description as set forth below.BRIEF SUMMARY OF THE INVENTION

[0004] An aspect of the invention provides a cylindrical hollow filter element comprises repeated segments, each segment comprising, in order: (a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3), wherein Hl <H2<H3; (b) a first septum LI having a pleat height LH1; (c) a second group of three pleats (M4, M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2, having a pleat height LH2; (e) inverted pleat W, having a pleat height WH; (!) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.

[0005] In accordance with an aspect of the invention, a cylindrical porous filter is provided, comprising an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage; the cylindrical hollow filter element comprising repeated segments, each segment comprising, in order: (a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3), wherein H1<H2<H3; (b) a first septum LI having a pleat height LH1; (c) a second group of three pleats (M4. M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2, having a pleat height LH2; (e)7751162inverted pleat W, having a pleat height WH: (f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.

[0006] In another aspect, a method of filtering fluid is provided, the method comprising passing the fluid through an aspect of a cylindrical porous filter comprising an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous filter element arranged in the annular gap between the inner core and the outer cage; the cylindrical hollow filter element comprising repeated segments, each segment comprising, in order: (a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3), wherein H1<H2<H3; (b) a first septum LI having a pleat height LH1; (c) a second group of three pleats (M4, M5. M6). having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2, having a pleat height LH2; (e) inverted pleat W, having a pleat height WH; (1) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0007] Figure 1 is a drawing showing, diagrammatically, a segment of a porous filter element having hybrid height pleats, comprising a first group of three pleats (Ml, M2, M3), followed by a first septum LI, followed by a second group of three pleats (M4, M5, M6), followed by a second septum L2, an inverted pleat W, and a third septum L3. wherein one side of L2 and one side of L3 form the inverted pleat W, according to an aspect of the invention. The Figure shows, in a direction from an outer perimeter to an inner perimeter, the first group of three pleats Ml -M3 sequentially increase in height from left to right, the second group of 3 pleats M4-M6 sequentially increase in height from left to right, and wherein each of the pleat heights in the second group are higher than each of the pleat heights in the first group, and the septa LI, L2, and L3, and the inverted pleat W have longer pleat heights than each of M1-M6. The filter element has a hollow cylindrical configuration, with repeating segments with the pleats and septa in a laid-over arrangement.

[0008] Figure 2A is a drawing showing, diagrammatically, a difference in pressure upstream (low to high to low) as fluid flows through the segment of filter element shown in7751163Figure 1. and Figure 2B shows the regions of the filter element exhibiting low pressure downstream, followed by high pressure, followed by low pressure, shown in Figure 2A according to an aspect of the invention.

[0009] Figures 3A and 3B are drawings showing, diagrammatically, a venturi zone (high pressure) boosting flow through the filter element created as fluid flows through filter element shown in Figure 1, according to an aspect of the invention. Figure 3B shows (darker / thicker line = prefiltratiom lighter / thinner line = post filtration) that the segment of the filter element has a first width Wi, and a second width W2, wherein Wi<W2, wherein, when fluid flows through the segment, a shiftable third width W3 is created betw een Wi and W2, wherein Ws<Wi<W2.

[0010] Figures 4A and 4B are CT-Scan photographs showing the changes in the shape of the pleats before (Figure 4A) and after (Figure 4B) fluid flow through the filter element (wherein the filter element is produced as described in Example 1), wherein the filter element, compressed with laid-over pleats has a cylindrical inner core coaxially disposed along the inner periphery of the pleated porous filter element, and a cylindrical cage disposed along the outer periphery of the filter element, and an annular gap is present betw een the inner core and the outer cage, with the pleated porous filter element arranged in the gap between the inner core and the outer cage. Changes in pleat gaps before and after fluid flow are measured, Table 1 showing the gap width measurements is provided in the specification below ; Figure 3B, described above, show s diagrammatically, the change in shape of the pleats prefiltration and post filtration). In Table 1, the vertical axes, measuring the distance in the direction from the outer cage to the inner core, represent different regions or zones within the pleat pack, and the horizontal axes represent an individual pleat in the region or zone, and the numbers represent the spacing distance betw een the pleat legs of each individual pleat. A diagrammatic representation of the values in Table 1 is shown in Figure 3B.

[0011] Figures 5 and 6 show, respectively, top and perspective views of the filter element without a core or surrounding outer cage.

[0012] Figure 7 show s a representation of theoretical inside-out flow through the filter element, showing that there are expected localized regions of high- and low-pressure within the element such that if fluid passes through the pack, the passage of fluid will cause a shift or deformation of the pleats to create the venturi effect.7751164

[0013] Figure 8 is a drawing showing a cut-away perspective diagrammatic view of a cylindrical hollow filter including a cylindrical hollow filter element with a plurality of segments as generally shown in Figure 1 (filter element not fully compressed) according to another aspect of the invention.DETAILED DESCRIPTION OF THE INVENTION

[0014] In accordance with an aspect of the invention, a cylindrical hollow filter element comprises repeated segments, each segment comprising, in order: (a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3), wherein H1<H2<H3; (b) a first septum LI having a pleat height LH1; (c) a second group of three pleats (M4, M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2, having a pleat height LH2; (e) inverted pleat W, having a pleat height WH; (I) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.

[0015] In accordance with an aspect of the invention, a cylindrical porous filter is provided, comprising an inner core and an outer cage, with an annular gap betw een the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage; the cylindrical hollow filter element comprising repeated segments, each segment comprising, in order: (a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3), wherein H1<H2<H3; (b) a first septum LI having a pleat height LH1; (c) a second group of three pleats (M4. M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2, having a pleat height LH2; (e) inverted pleat W, having a pleat height WH; (f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.

[0016] In another aspect, a method of filtering fluid is provided, the method comprising passing the fluid through an aspect of a cylindrical porous filter comprising an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous filter element arranged in the annular gap between the inner core and the outer cage; the cylindrical hollow filter element comprising repeated segments, each7751165segment comprising, in order: (a) a first group of three pleats (Ml. M2, M3), having corresponding pleat heights (Hl , H2, H3), wherein H1<H2<H3; (b) a first septum LI having a pleat height LH1; (c) a second group of three pleats (M4, M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2. having a pleat height LH2; (e) inverted pleat W. having a pleat height WH; (f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.

[0017] In one aspect, the method includes removing undesirable materials such as particulates from the fluid.

[0018] Alternatively, or additionally, aspects of the method can include processing fluid used in the microelectronics industry.

[0019] In an aspect, the filter element has a first width Wi, and a second width W2, wherein W i<W2. wherein, when fluid flows through the segment, a shiftable third width W3 is created between Wi and W2, wherein Ws<Wi<W2. Without being limited to any particular mechanism, it is believed that this shift creates a vacuum or venturi effect (see also, Figure 7).

[0020] In some aspects, it is believed that the use of the inverted pleat W controls pleat density to ensure that Wi<W2.

[0021] Advantageously, it is believed that as fluid is passed through the filter element, a vacuum or venturi effect is created, wherein creating a vacuum or venturi effect can provide for increased fluid flow through the filter element and increased reduction in undesirable components (e.g., contaminants such as particulates) in the filtered fluid. Filter elements, filters including the filter elements, and filter devices including the filters, can have lower packing densities and higher permeabilities, while maintaining desirable pressure differentials and reduced membrane area, while edge-flow resistance is reduced.

[0022] It is also believed that as fluid continues to pass through the filter element, after the shift of the shiftable third width W3 between Wi and W2, the shiftable third width W3 shifts to approach the larger width W2, and the vacuum or venturi effect ceases (see. for example, Figure 3B).7751166

[0023] Aspects of the invention are suitable for processing a wide variety of fluids, especially liquids, including, but not limited to, liquid (e g., aqueous) fluids fdtered in the microelectronics industry.

[0024] Aspects of the method can include outside-in flow in which a fluid to be fdtered flows from the outer cage through the fdter element into the inner core, and inside-out flow in which a fluid to be fdtered flows from the inner core through the fdter element through the outer cage.

[0025] Each of the components of the invention will now be described in more detail below, wherein like components have like reference numbers.

[0026] In accordance with aspects of the invention, a cylindrical hollow pleated porous fdter element comprises a pleated porous medium comprising a plurality of repeated fdter segments, each segment comprising a having pleats of different heights.

[0027] Figure 1 illustrates, diagrammatically (wherein, for ease of reference, the pleats in a segment are shown expanded before compression to form laid-over pleats, eventually forming a hollow cylindrical pleated porous fdter element 3000 that comprises a porous medium 500 (see also. Figures 4A, 4B; 5 and 6 (top and perspective views); and 8 (arranged with an inner core and outer cage)), an aspect of a segment 600, that comprises a first group GRP1 of three pleats (Ml, M2, M3), followed by a first septum LI, followed by a second group GRP2 of three pleats (M4, M5, M6), followed by a second septum L2, an inverted pleat W, and a third septum L3, wherein one side of L2 and one side of L3 form the inverted pleat W.

[0028] Figure 1 shows, in a direction from an outer perimeter to an inner perimeter, the first group GRP1 of three pleats M1-M3 sequentially increase in height from left to right, the second group GRP2 of 3 pleats M4-M6 sequentially increase in height from left to right, and wherein each of the pleat heights in the second group are higher than each of the pleat heights in the first group, and the septa LI, L2, and L3, and the inverted pleat W have longer pleat heights than each of M1-M6.

[0029] Thus, a cylindrical hollow pleated porous filter element 3000 comprises a plurality of segments, each segment comprising, in order: (a) a first group of three (longitudinal) pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3), wherein H1<H2<H3; (b) a first septum LI having a pleat height LH1; (c) a second group of three (longitudinal)7751167pleats (M4. M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3; (d) a second septum L2, having a pleat height LH2; (e) inverted (longitudinal counter-pleat) pleat W, having a pleat height WH; (f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.

[0030] Figure 2A is a drawing showing, diagrammatically, using a representative portion of the segment 600 of the filter element shown in Figure 1, a difference in pressure upstream (low to high to low-) as fluid flows through the filter element, and Figure 2B shows, diagrammatically, the regions of the filter element exhibiting low7pressure downstream, followed by high pressure, followed by low pressure, shown in Figure 2A.

[0031] Figures 3A and 3B are drawings showing, diagrammatically, again using a representative portion of the segment 600 of the filter element shown in Figure 1 (similar to that described with respect to Figures 2A and 2B), a venturi zone (high pressure) boosting flow through the filter element created as fluid flow s through filter element. Figure 3B shows (darker / thicker line = prefiltration; lighter / thinner line = post filtration) that the representative portion of the segment of the filter element has a first width Wi, and a second width W2, wherein Wi<W2. and wherein, when, post filtration, fluid flows through the segment, a shiftable third width W3 is created between Wi and W2, w herein W3<Wi<W2 (see also. Figure 7).

[0032] As the fluid continues to pass through the filter element, it is believed that after the shift of the shiftable third width W3 such that W3<Wi<W2, the shiftable third width Ws shifts to approach the larger width W2, and the vacuum or venturi effect ceases.

[0033] In the aspect shown before and after filtration in Figures 4A and 4B (fully compressed filter element with laid-over pleats), a cylindrical inner core 800 is coaxially disposed along the inner periphery of the pleated porous filter element 3000 comprising a porous medium 500, and a cylindrical cage 900 is disposed along the outer periphery of the filter element 3000, and an annular gap G is present betw een the inner core and the outer cage, with the pleated porous filter element arranged in the gap between the inner core and the outer cage, the gap having a width W. Changes in pleat gaps before and after fluid flow are measured. Table 1 showing the gap width measurements is provided in the specification below; Figure 3B, described above, shows diagrammatically, the change in shape of the pleats prefiltration and post filtration). In Table 1, the vertical axes, measuring the distance in7751168the direction from the outer cage to the inner core, represent different regions or zones within the pleat pack, and the horizontal axes represent an individual pleat in the region or zone, and the numbers represent the spacing distance between the pleat legs of each individual pleat. A diagrammatic representation of the values in Table 1 is show n in Figure 3B.775116Table 1Post filtration Prefiltration77511610

[0034] Thus, for example, as reflected in the highlighted text in one of the regions or zones in Table 1 , the average distance between the pleat legs is reduced from an average to 7.5 before fdtration to 6.96 after filtration (after filtration shown as “W3” in Figure 3B), reflecting the venturi effect, wherein the last values in the tables show the larger W2 in Figure 3B. In contrast with the data shown in Examples 2 and 3 below, there was an image resolution issue resulting in a correction as referenced in Table 1 above.

[0035] The radius per layer is inversely proportional to pleat density, the lower the number, the greater the pleat density. With reference to Figure 2B, the radius per layer is as follows:Table 2

[0036] Accordingly, region 2 shows the highest pleat density and lowest radius per layer, corresponding to the venturi zone W3.

[0037] As shown in Figures 4A-4B, the pleat-spacing is different in the pleat-pack both before, and after, fluid flow. Before fluid flow the pleat pack is stabilized to enable uniform packing during pleat-forming. However, after fluid flow, based on the inter-pleat compression and differential pressure, the pleat pack deforms and a venturi zone is created in the downstream between the pleats. A thin / narrow gap is created between the pleats around central height of the pleat. This ensures that a localized vacuum zone is created between the pleats during the flow to deliver the high thrust flow. This is reflected in the pleat spacing after the flow; the pleat-gaps in the downstream after the flow appear narrow (inter-pleat gap dimensions are reduced downstream relative to upstream)

[0038] In some aspects, the filter element is arranged based on the following:

[0039] Wi and W2 gaps are to maintain venturi effect.; Wi = 20%-30% larger than the venturi zone (W3); W3 (Venturi Zone) = 10%-l 5% larger then total thickness of the filter media. Desirably, to allow shrinkage during vacuum effect and still maintain sufficient flow; W2 = 30%-40% larger than the venturi zone (W3).

[0040] There are no particular restrictions on the type of porous filter medium 500 (see, Figs. 1. 4A, 4B, 5, 6, and 8) which can be employed in the porous filter element of the present invention, and it can be selected in accordance with the fluid which is to be filtered and the desired filtering characteristics. Preferably, the porous filter medium / filter element comprises a polymeric medium. The filter element / filter can be used to filter fluids such as liquids, gases, or mixtures thereof used in various industries. For example, the filter element / filter can be used to filter process fluids in the microelectronic industry for wet-etch cleans (e.g., a material removal process that uses liquid chemicals or etchants to remove materials from a wafer). CMP (chemical-mechanical planarization), for producing ultrapure water (UPW), and for lithography modules, and the fluids can include, for example, standard clean 1 (SCI) fluids, standard clean 2 (SC2) fluids, Isopropyl Alcohol (IP A; including hot IP A), Sulfuric Acid (H2SO4 including hot H2SO4), Tetramethyl quaternary ammonium hydroxide (TMAH; including hot TAMH), hydrogen peroxide (H2O2, including hot H2O2), Ammonium Hydroxide (NH4OH; including hot NH4OH), and Hydrogen Fluoride (HF; including hot HF), among others, used independently or mixed with each other.

[0041] Typically, the pleated porous filter element comprises, or is, a membrane. The membranes can have any suitable pore structure, e.g., a pore size (for example, as evidenced by bubble point, or by KL as described in, for example, U.S. Patent 4,340,479, or evidenced by capillary condensation flow porometry), an average pore size; a mean flow pore (MFP) size (e.g., when characterized using a porometer, for example, a Porvair Poro meter (Porvair pic, Norfolk, UK), or a porometer available under the trademark POROLUX (Porometer.com; Belgium)), a pore rating, a pore diameter (e.g., when characterized using the modified OSU F2 test as described in, for example, U.S. Patent 4,925,572), or removal rating media. The pore structure used depends on the size of the particles to be utilized, the composition of the fluid to be treated, and the desired effluent level of the treated fluid. In some aspects, the membrane has (depending on the application), an average pore size in the range of 10 nm to 1 micron.

[0042] The porous membrane can have any desired critical weting surface tension (CWST, as defined in, for example, U.S. Patent 4,925,572). The CWST can be selected as is known in the art, e.g., as additionally disclosed in, for example, U.S. Patents 5,152,905, 5,443,743, 5,472,621, and 6,074,869. Typically, the membrane has a CWST of in the range of 28 dynes / cm (28 x 10'5N / cm) to 34 dynes / cm (34 x 10'5N / cm).

[0043] Exemplary membranes are disclosed in U.S. Patents 4,702,840 and 4,900,449. Other membranes, including those disclosed in U.S. Patents 4,906,374; 4,886,836; 4.964,989; 5,019,260; 4,340,479; 4,855,163; 4,744,132; 4,707,266; 4,203,848; 4,618,533, 6,039,872; 6,780,327; 6,783,937; and 7,189,322, may also be suitable. Exemplary' membranes include, but are not limited to, nylon membranes, polytetrafluoroethylene (PTFE) membranes, high-density polyethylene (HDPE) membranes, and highly asymmetric polyarylsulfone (HAPAS) membranes. Exemplary' membranes may be used individually or in combination with any other exemplary membranes having the same or different characteristics.

[0044] The filter / filter element can include additional elements, layers, or components, that can have different structures and / or functions, e.g., at least one of any one or more of the following: prefiltration, support, drainage, spacing and cushioning.

[0045] For example, in the aspect of the filter 3100 as shown in Figure 8 (wherein the filter element 3000 is shown diagrammatically, not fully compressed), in addition to a cylindrical perforated inner core 800 coaxially disposed along the inner periphery of the filter element and a cylindrical outer cage 900 disposed along the outer periphery of the filter element 3000, the illustrated filter includes a first pleated mesh 501 contacting a first (e.g., upstream) surface of the porous medium 500 of the filter element, and a second pleated mesh 502 contacting a second (e.g., downstream) surface of the porous medium 500 of the filter element, providing a three-layer composite. The components (meshes, filter medium) forming the filter element can be formed into a composite by conventional filter manufacturing techniques, either prior to or simultaneous with corrugation.

[0046] The meshes (the term “mesh” also includes “screen”) prevent opposing surfaces of the filter medium from coming into contact with one another and enables fluid to evenly flow to or from substantially all portions of the surface of the filter medium when the pleats are in the laid-over state. Thus, virtually the entire surface area of the filter medium may be effectively used for filtration.13

[0047] A variety of meshes are suitable for use in aspects of the invention. The meshes can be made of any materials having suitable edgewise flow characteristics, i.e., suitable resistance to fluid flow through the layer in a direction parallel to its surface. The edgewise flow resistance of the drainage meshes is preferably low enough that the pressure drop in the drainage layer is less than the pressure drop across the fdter medium, thereby providing an even distribution of fluid along the surface of the fdter medium.

[0048] Typically, a fdter 3100 according to an aspect of the present invention will be equipped with end caps 850 (only one of which is show n in Fig. 8) at one or both ends of the fdter element 3000. The end caps 850 can be either blind (closed) or open end caps, and the material of which they are formed and their shape can be selected in accordance with the filtering conditions and the materials of the members to which the end caps are to be joined. Preferably, the end caps 850 are attached to the fdter element 3000, but they may also be attached to the inner core 800 or the outer cage 900. Conventional techniques can be used to attach the end caps to the fdter element.

[0049] If desired, in some aspects, an insert in the form of a strip of material having a good affinity for the end cap material can be corrugated into the ends of the fdter element 3000 to improve the seal between both ends of the fdter element 3000 and the end caps 850. For example, when the end caps are made of a fluoropolymer, a strip of another fluoropolymer, such as a fluorinated ethylene-propylene (FEP) resin, can be corrugated into the ends of the fdter element as the insert. The insert need only be wide enough to bond the fdter medium to the end cap, and therefore, it might extends for only a portion of the axial length of the fdter element 3000. A typical width for the insert is approximately 0.5 inches.

[0050] Aspects of the fdter device and fdter are suitable for outside-in flow in which a fluid to be filtered flows from an outer periphery (e.g., the outer cage) through the fdter element into the hollow center (e.g., the inner core) and through the outlet, and inside-out flow in which fluid to be filtered flows from the hollow center, through the fdter element through the outer periphery’ and through the outlet.

[0051] The fdter element 3000 illustrated in Figure 8 (showing laid-over pleats) can be manufactured by a variety of techniques, for example, as described in U.S. Patent 5,543,047.77511614

[0052] The filter comprising the filter element is disposed in a housing comprising at least one inlet and at least one outlet and defining at least one fluid flow path between the inlet and the outlet, wherein the filter is across the fluid flow path, to provide a filter device. Preferably, the filter device is sterilizable. Any housing of suitable shape and providing at least one inlet and at least one outlet may be employed.

[0053] The housing can be fabricated from any suitable rigid impervious material, including any impervious thermoplastic material, which is compatible with the fluid being processed. For example, the housing can be fabricated from a metal, such as stainless steel, or from a polymer. In a preferred aspect, the housing is a polymer, in some aspects, a transparent or translucent polymer, such as an acrylic, polypropylene, polystyrene, or a poly carbonated resin.

[0054] The following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope.EXAMPLE 1

[0055] This example demonstrates the improved results using a filter including a filter element according to an aspect of the invention compared to other commercially available filters.

[0056] A laid-over filter element is produced having repeated segments as generally illustrated in Figure 1, with pleat heights as follows:

[0057] In one test, the filter element, core, cage, and endcaps of the filter are high-density polyethylene (HDPE). In another test, the filter element is polytetrafluoroethylene (PTFE). The filter elements are corrugated using a JCEM Group GmbH corrugator.77511615

[0058] A commercially available laid-over pleat filter is obtained. The commercially available filter has 10% greater total area than the filters according to aspects of the invention.

[0059] The filters are tested, and the filter according to an aspect of the invention has a similar or improved pressure drop compared to the commercially available filter but at a lower membrane area. This improves the overall filter permeability (flow per unit area per unit Delta P).

[0060] With respect to the tested PTFE filter, the improved flow-efficiency results in enhanced initial cleanliness. The particle counts (Lipid particle counts (LPC) in deionized water) and metal extraction values for the PTFE filter according to an aspect of the invention are significantly lower than those for the commercially available filter. This results in a PTFE device with enhanced initial cleanliness.EXAMPLE 2

[0061] This example shows another set of prefiltration and post filtration pleat gap measurements using a filter element as descnbed in Example 1. The results are shown in the following Table 2.Table 2Post filtration Prefiltration

[0062] Similar to the results shown in Table 1, the data shows, post filtration, the pleat gap narrowing from the top, narrower at the venturi region, widening toward the bottom. If shown diagrammatically, the post filtration would be represented by an hour-glass shape, as shown in Figure 3B.EXAMPLE 3

[0063] This example shows another set of prefiltration and post filtration pleat gap measurements using a filter element as described in Example 1. The results are shown in the following Table 3.18Table 3Post filtration Prefiltration77511619

[0064] Similar to the results shown in Table 1 and in Table 2 (Example 2), the data shows, post filtration, the pleat gap narrowing from the top, narrower at the venturi region, widening toward the bottom. If shown diagrammatically, the post filtration would be represented by an hour-glass shape, as shown in Figure 3B.

[0065] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0066] The use of the terms “a” and '‘an’’ and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to.”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0067] Preferred aspects of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred aspects may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically77511620described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherw ise indicated herein or otherwise clearly contradicted by context.

Claims

77511621CLAIM(S):

1. A cylindrical hollow filter element comprising repeated segments, each segment comprising, in order:(a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3). wherein H1<H2<H3;(b) a first septum L 1 having a pleat height LH 1 ;(c) a second group of three pleats (M4, M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3;(d) a second septum L2, having a pleat height LH2;(e) inverted pleat W, having a pleat height WH;(f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1. LH2, LH3, and WH, are each greater than each of H1-H6.

2. A cylindrical porous filter comprising:an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage; the cylindrical hollow filter element comprising repeated segments, each segment comprising, in order:(a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3). wherein H1<H2<H3;(b) a first septum L 1 having a pleat height LH1 ;(c) a second group of three pleats (M4, M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3;(d) a second septum L2, having a pleat height LH2;(e) inverted pleat W, having a pleat height WH;(f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and wherein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.775116223. A method of filtering fluid, the method comprising passing the fluid through a cylindrical porous filter comprising:an inner core and an outer cage, w ith an annular gap between the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage; the cylindrical hollow filter element comprising repeated segments, each segment comprising, in order:(a) a first group of three pleats (Ml, M2, M3), having corresponding pleat heights (Hl, H2, H3), wherein H1<H2<H3;(b) a first septum L 1 having a pleat height LH 1 ;(c) a second group of three pleats (M4, M5, M6), having corresponding pleat heights (H4, H5, H6), wherein H4<H5<H6, and H4>H1, H5>H2, and H6>H3;(d) a second septum L2, having a pleat height LH2;(e) inverted pleat W, having a pleat height WH;(f) third septum L3, having a pleat height LH3, wherein one side of L2 and one side of L3 form the inverted pleat W, and w herein LH1, LH2, LH3, and WH, are each greater than each of H1-H6.

4. The method of claim 3, including creating a venturi effect as fluid passes through the cylindrical porous filter.

5. The method of claim 3 or 4, including removing particulates from the fluid as the fluid passes through the cylindrical porous filter.

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