Extended Life Panel Filter

A panel filter is provided. The panel filter can have extended life by virtue of more filter media packed into a panel filter in a way that maintains open flow structure and with filter media selection that does not cause undue restriction.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2illustrate embodiments of a panel filter10of the present invention. The panel filter10generally includes a pleated filter media12that is arranged in a rectangular card-like structure and that is maintained in that rectangular card-like configuration by a suitable support structure such as one of preferably two die cut paperboard frames14, as shown.

The pleated filter media12is formed from a relatively thin porous material such as an entanglement of polymeric fibers and/or cellulose or glass fibers that permits air to readily pass through, but intercepts solid particles such as dust, lint and the like. The panel filter10illustrated is particularly suited for Heating, Ventilation and Air Conditioning (HVAC) systems that employ forced air such as used in homes, offices and other such buildings. The filter media is folded into multiple pleats16to provide sets of pleat tips35on each side (both inlet and outlet sides) of the panel filter10.

As shown, a high pleat density is obtained with the full face of pleat flanks exposed during use (not blinded) with structural support discussed herein with a pleat density greater than the typical 3.5 pleats per inch used in typical HVAC applications. Further, greater than 5 square feet of filter media may then be contained per square foot defined by the respective spans of the panel filter and measured per ⅞″ depth of the pleats.

As for size, for typical HVAC applications, the panel filter100may span a first lateral span18of between 12 and 30 inches and a second lateral span20transverse to the first span that is also between about 12 and 30 inches. Pleat depth can be measured normal to these spans18and20.

In the embodiment shown inFIG. 1and also demonstrated byFIGS. 3 and 5, each of the inlet side24and outlet side26of the pleated filter media12are supported by a rectangular paperboard frame14, which may be a one piece die cut frame. Alternatively, border frames, edge band frames or the like, may be used. The frames14are telescopically interfit with each other with each frame covering one of the inlet side and outlet side.

With this configuration and with adhesive28laminated to the inner surfaces of each of the frames14, it can be seen that the filter media12is supported and protected with integral webbing30that extends transverse across a rectangular border32of each frame14. The adhesive28may be applied with a roller coater prior to the assembly shown inFIG. 5such as when the die cut frame14is folded flat prior to being assembled into the semi-boxlike configuration shown inFIG. 5. With this configuration, the pleat tips35along both the inlet side24and outlet side26are adhesively secured to the integral webbing30of the frame. Further, adhesive secures and seals between the outer rectangular periphery of the pleated filter media12and the inner periphery of the rectangular border32provided by the frames14.

The integral webbing30may be formed when multiple holes31are cut out from the filter frame material during a frame die cutting process. The integral webbing30may have generally diagonal shaped holes31with each hole providing between 6 and 20 square inches area opening. As a result, sufficient airflow is achieved and no restriction due to the integral webbing is realized or such restriction is otherwise de minimis.

To achieve an organized filter media configuration with high pleat density without unduly restricting airflow, the embodiment employ adhesive spacer beads36, which are laid down by an adhesive bead line applied upon both the inlet side24and outlet side26of the pleated filter media during manufacture. The beads36, serve to provide structural support to the pleated filter media to hold the structure into a rectangular filter media pack22.

Generally, the adhesive spacer beads36are continuous strips of adhesive that are laid as the media is being run in the direction of the second span in a continuous manner over each of the inlet side24and outlet side26to form the adhesive spacer beads36on opposing sides of the filter media, thereby forming the filter media pack22. As can be seen, the adhesive spacer beads36therefore extend up and over pleat tips and down into pleat valleys along the pleat flanks at least partially into the V-shaped channels formed between adjacent pleat flanks and in some embodiments may reach all the way to the bottom of such V-shaped channels as the adhesive spacer beads are laid continuously.

The adhesive spacer beads may be laid down in parallel lines at a spacing (relative to the next adjacent adhesive bead) between ½ and 4 inches and in some embodiments, more preferably between 1 and 2 inches. This provides sufficient structural support to maintain the pleat shape and V-shaped channels37with sufficient open volume to provide airflow without undue restriction. The adhesive spacer beads36also afford support to prevent the pleats from collapsing and contacting each other to prevent blinding off the filter media during operation. For example, V-shaped channels37do not deform or collapse very much during use, which maintains airflow into the channels to move through filter media of pleat flanks. As a result, much more of the surface area of the pleated filter media12is exposed for full filtration and dust loading purposes. Further, the configuration allows for dust cake accumulation without prematurely filling or blocking the V-shaped channels37with this pleat density and support structure configuration.

To assist in the spacing and structural integrity, various embossments38are provided to widen the pleat flanks at the select areas where the adhesive spacer beads36are laid down. This can be seen, for example, inFIG. 4whereby embossments are formed such as by heat setting and/or compression forming into the pleat flanks34every one to 2 inches (or between ½ and four inches in some other embodiments depending upon the spacing of the adhesive spacer beads36). Embossments38provided a shorter span needed for the adhesive to bridge across the V-shaped channels37between adjacent pleats. Additionally, additional embossments39may be interspaced between the adhesive spacer bead embossments38as illustrated also at a similar spacing of the adhesive spacer bead embossments38. These other embossments39do not receive a glue bead, but provide for additional structural support and also prevent flat surface-to-surface contact between filter media along the pleat flanks34in response to airflow forces during use.

Referring toFIG. 2, it can be seen that this may provide a filter media pack22that has employed the adhesive spacer beads36and embossments39,39such that the filter media pack22is ready to be framed via frames14for use to create the panel filter shown inFIG. 1. Alternatively, the adhesive spacer beads36may provide the support structure to maintain the pack in the rectangular configuration and as such, itself may form a panel filter with this support structure in an embodiment.

However, it should be noted that preferably, additional structure such as an outer peripheral frame structure such as planar edge bands50may be laminated across the zig-zagging end faces52at opposing ends of the filter media pack22as shown inFIGS. 9 and 10to provide yet another embodiment of a panel filter54. The edge bands50may comprise planar strips of filter media, which may then be adhesively secured to the end faces at two opposed ends of the filter media pack22or can be heat set and heat welded to the ends to provide sufficiently stiff structure. The final pleat flank at either the other two end faces of panel filter54may be free and may be used as compression end pleats in a suitable housing such as filter housing58, which is shown as a rectangular frame having a side entry opening and track to slidably receive the panel filter54. The end pleat flank56on the two free sides (not constrained by edge bands50) can be free to be compressed or otherwise trapped by filter housing58to thereby better ensure that airflow is directed through the filter media pack22.

As evident in embodiments above, to provide a support structure for supporting the media in a rectangular configuration, various frames, scrims, bands and the like may be used in addition to, or in the alternative to those disclosed according to the embodiments described above. Support structures in various other embodiments of the present application may be used such as disclosed in U.S. Patent Publication Number 2012/0167535 entitled, “Self Supported Pleated Panel Filter With Frayed Edges”; U.S. Patent Publication Number 2010/0269468 entitled, “Panel Filter”; U.S. 2010/0269467 entitled, “Panel Filter”; U.S. Pat. No. 7,537,632 entitled, “Panel Filter With Frame”; U.S. Patent Publication Number 2005/224170 entitled, “Method and System for Making Filters”; and U.S. Pat. No. 5,782,944. Each of these patents are incorporated by reference in their entireties for support structures and panel filter details may be used as alternatives or an addition to those in embodiments discussed specifically herein.

As demonstrated in embodiments above, to better facilitate for structural integrity and high air flow while at the same time packing more media into a tighter configuration with increased pleat density, some embodiments may include pleat supports and spacers between adjacent pleat flanks34. For filter elements configured to operate in high-flow-rate environments, spacers, such as plastic finger spacers or hot-melt adhesives spaced at regular intervals, may be placed at regular intervals along the pleated filter media to add structural rigidity and prevent deformation of the media. In addition to being pleated with heat setting of the pleats, the filter media may also be embossed to add structural rigidity, to further increase surface area, and to increase amount of media that can be manipulated into a volume for the panel filter10. A method of embossed filter media is described in U.S. Pat. No. 6,685,833. U.S. Pat. No. 5,290,447, U.S. Pat. No. 5,804,014 and DE 19755466 A1 also describe methods of embossing that, in some embodiments, may be applied to the composite filter media of the present invention as an addition or alternative. Each of these patents are incorporated by reference in their entireties, as these or other pleating and embossing technologies may be used.

For example, integrally formed embossments38(grooves, folds or wrinkles extending between pleat tips35and between inlet and outlet faces) formed into the filter media and adhesive spacer beads36are illustrated on the filter media of filter media pack22as shown inFIGS. 1-5. Various numbers and arrangements of embossments can be provided. The adhesive beads are on adjacent pleat tips and extend along pleat sides and attach to each other as shown. This provides consistent pleat spacing and structural integrity to the pleated filter pack. Adjacent pleat tips may be spaced between ¼ and ¾ centimeter to compact a substantial amount of filter media into the envelope while at the same time keeping an open flow structure to accommodate high air flow capacity. Also, the peat tips may be flattened with two creased edges40and a flat42therebetween as schematically illustrated inFIG. 35. Flats42may between 0.5-2.5 millimeters wide in some embodiments.

To better facilitate for structural integrity and high air flow, some preferred embodiments may include additional pleat supports and spacers between adjacent pleat flanks34. For filter elements configured to operate in high-flow-rate environments, spacers, such as plastic finger spacers or hot-melt adhesives spaced at regular intervals, may be placed at regular intervals along the pleated filter media to add structural rigidity and prevent deformation of the media. In addition to being pleated with heat setting of the pleats (e.g. with bicomponent filter media with high melt and low melt fibers and/or high melt and low melt components in fibers), the filter media may also be embossed to add structural rigidity, to further increase surface area, and to increase amount of media that can be manipulated into a volume for panel filter. Any of these aforementioned structures may be employed as support structure to maintain a rectangular configuration as an alternative to or in addition to frames (e.g. die cut frames and/or edge banding).

Filter Medias

In embodiments, the filter media may comprise non-woven polymeric and preferably polyolefin fibers a basis weight of between 65 and 80 grams per square meter and a media thickness of between 0.3 and 0.7 millimeters, thereby providing for high loft. The high loft provides a high dust loading capability and air permeability. Preferably, the polymeric fibers contain fluorine and provide an electrostatic charge to provide the filter media with at least a MERV 12 or higher rating, wherein the filter media without the fluorine and electrostatic charge comprises between a MERV 7-11 rating. The electret can allow for a more open less restrictive media such that restriction is not necessarily increased with pleat density. An air permeability of between 150 and 250 cfm at 0.5 inch WG pressure may be provided flat sheet media testing. To provide for heat setting of pleats, the filter media base preferably includes a component polymeric structure including a high melt polymer and a low melt polymer

For example, the filter media may be charged to an electret with surface fluorination, which may be according to U.S. Pat. No. 6,419,871, assigned to Transweb, LLC. Other fluorination methods may include the addition of fluorochemicals according to U.S. Pat. Nos. 5,411,576 and 5,472,481 to Jones et al and/or U.S. Pat. No. 5,908,598 to Rousseau et al. Each of the patents referenced in this paragraph are thus incorporated by reference in their entirety.

One embodiment uses filter media grade KC621L XZPN, which is commercially available from Transweb LLC, of Vineland, N.J., with reported properties in the table below:

Panel Filter Sizes & Media Pack Amounts & Pleat Spacing

Generally in the panel filter art, the sizes are relatively standard. A common size is a 20 inch×20 inch×1 inch filter. This means the filter will fit an envelope of that size but is typically a bit smaller to allow for easy installation. For example, the actual depth of the filter frame may be 15/16 of an inch and the pleat depth about ⅞ inch for a 1 inch fitting filter. Similarly, the pleat depth for a 2 inch fitting filter may be 1 and ¾ inch. Therefore, useful measures are made using these depths.

For most panel filters, the pleat depth is less than 3 inches (typically either 2 inches or 1 inch), with lateral width spans each spanning between 12 inches and 30 inches (fractions being rounded up in this instance considering that the panel filter element need only fit an envelope that size). With the increased media packed into the panel filter, for example the amount of filter media per square foot for the most common sized filters may be set forth in the following table for various embodiments:

As is evident from the above and with the configuration afforded to the panel filter with various embodiments of the present invention whereby the filter media is formed into a compacted pleat pack, more than 5 square feet of filter media is contained per square foot defined by the width spans and measured per ⅞ inch depth of pleat depth. More preferably, more than 6 or 7 square feet of filter media is contained per square foot defined by the panel filter width spans and measured per ⅞ inch depth of pleat depth, with some preferred embodiments more than 7.5 square feet of filter media is contained per square foot defined by the first and second spans and measured per ⅞ inch depth of pleat depth. By way of example, the 20×20×1 covers a lateral area of 400 square inches or 2.778 square feet and therefore about 7.61 square feet of filter media can be pleated and contained per square foot defined by the panel filter width spans and measured per ⅞ inch depth of pleat depth.

For a 2 inch depth fitting filter, the later width span sizes may be the same, but it will be appreciated that the gross amount of square feet of media per filter is about double as the pleat depth has about doubled. However, the amount of filter media contained per square foot defined by the width spans and measured per ⅞ inch depth of pleat depth is comparable to the 1 inch fitting filter elements. As such also for two inch elements, the preferred ranges mentioned in the preceding paragraph and herein throughout are also generally applicable to 2 inch fitting filter elements, unless otherwise stated or self-evident to one of ordinary skill in the art.

To provide the increased density of filter media, one of the ways to accomplish the same is by increasing pleat density to a tighter density with decreasing pleat depth. In many embodiments, the pleated media comprises more than 3.5 pleats per inch along the second span, and more preferably, the pleated media comprises at least 4 pleats per inch along the second span and even more preferably, pleated media comprises at least 4.5 pleats per inch along the second span or more. Pleat density can be measured at pleat tips (e.g. counting the number of pleat tips per inch).

To avoid undue restriction, the embossments and/or the adhesive spacers serve to provide support to the pleats to ensure open areas for air to enter between pleats.

A relatively high loft media such as described herein can be selected in many embodiments to achieve reduced restriction and higher air flow.

At the same time, an electret filter media, that is a media with an electrostatic charge, may be used to provide higher efficiency for particle capture and retention, despite the more open media.

A KC621LXZPN filter media of Transweb, LLC was heat set embossed with adhesive bead spaces and arranged in filter cartridge in a 20×20×1 configuration (with about 21 square feet of media) according to an embodiment ofFIG. 1described above and then subjected to testing against other non-embossed medias for panel filters. The pleat spacing was 4.5 pleats-5.0 pleats per inch.

Results demonstrating a high particle capture efficiency (MERV rating) with a high dust holding capacity are demonstrated in the following table.

Comparisons were made with a 20×20×1 panel filter made with embossed KC621LXZPN filter media of Transweb, LLC (Purofied E-Plt RPG 5450) with other comparative 20×20×1 filters. Results are shown in the following table. From this, the average of dust holding capacity of 48 grams of test dust while Purofied E-Plt RPG 5450 would have an average dust holding capacity of 108 grams. From this, the normal service life expectancy and interval of 90 days, could be extended to 180 days.

Testing Standards

For the tests and standards discussed herein, the following can be used: ASHRAE #2 test dust obtained from Powder Technology, Inc. This test dust consists of 93.5% ISO 12103-1 A2 Fine plus 6.5% cotton linters. This dust is specified for use in AHRI Standard 680-2009 “Performance Rating of Residential Air Filter Equipment”. Test conditions include air temperature between 68 and 73 degrees Fahrenheit, relative humidity of between 46-50%, test aerosol of KCL, barometric pressure (in. HG) of between 29.32-29.38, particle counter being an S3I System. Face velocity for testing was 295 FPM (819 cfm air flow for a 20×20×1), with dust holding capacity being determined when a pressure drop and resistance of 1.00 WG pressure was measured.

Generally the protocols followed are a full 52.2-2007 ASHRAE Test, MERV 5-16 procedure with AHRI Test Dust.