Patent Application
20140165839
This invention generally relates to air filters, and more particularly relates to panel air filters that are used, for example, in Heating, Ventilation and Air Conditioning (HVAC) systems.
Paneled air filters are commonly used for filtering air in forced air systems such as Heating, Ventilation and Air Conditioning systems, commonly known as HVAC. Panel air filters generally comprise a rectangular filter media pack supported by a support structure in a rectangular configuration such as being surrounded and supported by a die cut paper board panel frame or by strips, bands, scrims, screens or the like.
One common type of filter media used in panel filters is pleated filter media that includes a plurality of peaks and valleys. Various prior art implementations are known to support pleated filter media so that the panel filters may withstand air pressure during operation. Such prior art includes U.S. Pat. No. 6,709,480 to Sundet et al.; U.S. Pat. No. 5,782,944 to Justice; and U.S. Patent Publication Number 2007/0294988 assigned to the present assignee, the entire disclosures of which are hereby incorporated by reference thereto.
Generally, in panel filter implementations for HVAC, there are competing interests involved. On the one hand, a panel filter must provide sufficient dust holding capacity without plugging prematurely to provide adequate filter life span. Additionally, the filter has to provide a suitable particle capture efficiency by removing sufficiently small particles such as dust and allergens from the air that are known to be entrained in such forced air ventilation systems. Often, a Minimum Efficiency Reporting Value (MERV) value of at least 11 or greater is desired for such forced air applications.
On the other hand, it is desirable not to restrict the flow of air and thereby provide for an open filter structure that allows for easy air flow through the pleated panel filter. The primary reason is that plugging is determined by the pressure drop that is experienced across the filter. Additionally, restricting airflow makes it harder for an HVAC system to deliver hot, cold and/or ventilated air resulting in energy loss. One test for determining the service life of a filter is evaluating dust holding capacity of the filter when the final resistance or pressure drop across the filter reaches one inch in water gauge pressure at a face velocity of 295 feet per minute. Thus, while a restrictive media is desired so as to enable adequate particle capture efficiency, a more open media is desired for air flow characteristics and to prevent premature clogging.
As a result, prior art panel filters have often been a compromise between these two competing interests. In many applications, a service life interval of 90 days for normal usage parameters is often suggested for air filters, which correlates to the pressure drop service life interval may also be determined, in part, by the dust holding capacity needed for 90 days in a typical building, that is experienced at the one inch water gauge in pressure drop.
To provide for a sufficiently open air flow media, prior art panel filters have employed a pleat spacing that is conventionally 3.5 pleats per inch, or less, so as to allow for sufficient air flow gaps between pleats to withstand the high air flow. Oftentimes, many prior art filters have included between 2 and 3.5 pleats per inch. Applicant believes total amount of media of the prior art is typically less than five square feet of filter media contained per square foot, per ⅞ inch depth of media defined by normal 1″ or 2″ fitting filters (i.e. defined by a square foot of the panel filter and measured per ⅞ inch of pleat depth).
Various embodiments of the present invention provide for an extended life panel filter or a panel filter that is able to load with substantially more dust with an expanded dust holding capacity. In some embodiments, it is provided by packing more filter media in an organized fashion into a panel of filter media while at the same time, maintaining sufficiently open structure to avoid air flow restriction. Media can be selected appropriately as discussed herein. With this, an extended life service is provided with panel filters according to various embodiments of the present invention.
According to one aspect of the present invention, a panel filter comprises a panel of filter media that is pleated. The panel has pleats with pleat tips spanning a first span. The panel spans a second span transverse to the pleat tips. The pleats define a pleat depth normal to the first and second span. In accordance with this aspect, more than five 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. The panel filter also includes a support structure supporting the filter media in a rectangular configuration.
For typical HVAC panel filter applications, the pleat depth is less than 3 inches such as a 1″ fitting or 2″ fitting filter element and, typically, the widths of the first and second spans each span between 12 and 30 inches (with any fractions being rounded up to the next highest number for this parameter).
Preferably, even more than 5 square feet of filter media is contained for the volume envelope measurement defined above. Preferably more than 6 square feet of filter media is provided, even more preferred more than 7 square feet of filter media and most preferably, more than 7.5 square feet of filter media is provided.
The panel filter media can provide a dust holding capacity of greater than 25 grams of Ashrae #2 test dust per square foot of the panel filter (measured again by the two lateral spans), measured at a face velocity of 295 feet per minute and upon reaching a resistance of 1″ water gauge pressure. The dust holding capacity may preferably be greater than 30 grams and in certain preferred embodiments greater than 35 grams.
Further, the panel filter may have at least a MERV 12 rating or higher, but it will typically at least be MERV 11 rating for many embodiments.
Preferably, the filter media comprises polymeric fibers with a basis weight of between 65 and 80 grams per square media, with a media thickness of between 0.3 and 0.7 millimeters thereby providing for high loft. The filter media may be an electret with polymeric fibers containing fluorine with an electrostatic charge to provide the filter media with at least a MERV 12 or higher rating (without such fluorine in charge, the filter media may otherwise comprise between a MERV 7-11 rating).
In various embodiments to provide for sufficiently open structure between pleats, the polymeric fibers of filter media may be heat set and embossed with spacer supports between pleat flanks such as integrally laid lines of adhesive spacer supports extending around pleat tips and connecting with adjacent pleat tips.
Another aspect of the present invention may relate to a method of extending a replacement service interval of an HVAC system employing a panel filter according to the above aspect and any of the additional noted other features that may be employed above. The method may comprise providing the panel filter in the rectangular configuration and installing the panel filter into an HVAC system to filter air flowing along the HVAC system.
According to this method, the service interval may be increased by at least 1.5 times relative to an original panel filter that was installed in the HVAC system and more preferably, doubling the service interval time. Therefore, for example, a 90 day service interval may be doubled to 180 days or at least may be increased to 135 days while achieving the same dust loading capabilities without increasing restriction.
Another different inventive aspect of the present invention is directed toward a panel filter with embossments and adhesive spacer supports to provide for more open flow type filter media. A panel filter, according to this aspect, comprises a panel filter media that is pleated wherein the panel has pleats with pleat tips spanning a first span. The panel filter spans a second span transverse to the pleat tips. The pleats define a pleat depth normal to the first and second spans with the filter media being pleated to a depth of less than 3 inches. The pleats have embossments extending between pleat tips (e.g. formed into and along pleat flanks) and adhesive spacer supports extending around pleat tips and along the embossments and connecting with adjacent pleat tips. The panel filter further can include additional support structure supporting the filter media in a rectangular configuration.
Yet another different inventive aspect pertains to a panel filter with an increased pleat density that is more than 3.5 pleats per inch along the second span, which is transverse to the pleat tips. This panel filter includes a panel filter media that is pleated wherein the panel filter has pleats with pleat tips spanning a first span in the panel spanning a second span transverse to the pleat tips. The pleats define a pleat depth normal to the first and second span with the pleated media comprising more than 3.5 pleats per inch along the second span. The support structure is provided for supporting the filter media in a rectangular configuration.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
The pleated filter media 12 is 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 filter 10 illustrated 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 pleats 16 to provide sets of pleat tips 35 on each side (both inlet and outlet sides) of the panel filter 10.
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 filter 100 may span a first lateral span 18 of between 12 and 30 inches and a second lateral span 20 transverse to the first span that is also between about 12 and 30 inches. Pleat depth can be measured normal to these spans 18 and 20.
In the embodiment shown in
With this configuration and with adhesive 28 laminated to the inner surfaces of each of the frames 14, it can be seen that the filter media 12 is supported and protected with integral webbing 30 that extends transverse across a rectangular border 32 of each frame 14. The adhesive 28 may be applied with a roller coater prior to the assembly shown in
The integral webbing 30 may be formed when multiple holes 31 are cut out from the filter frame material during a frame die cutting process. The integral webbing 30 may have generally diagonal shaped holes 31 with 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 beads 36, which are laid down by an adhesive bead line applied upon both the inlet side 24 and outlet side 26 of the pleated filter media during manufacture. The beads 36, serve to provide structural support to the pleated filter media to hold the structure into a rectangular filter media pack 22.
Generally, the adhesive spacer beads 36 are 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 side 24 and outlet side 26 to form the adhesive spacer beads 36 on opposing sides of the filter media, thereby forming the filter media pack 22. As can be seen, the adhesive spacer beads 36 therefore 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 channels 37 with sufficient open volume to provide airflow without undue restriction. The adhesive spacer beads 36 also 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 channels 37 do 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 media 12 is exposed for full filtration and dust loading purposes. Further, the configuration allows for dust cake accumulation without prematurely filling or blocking the V-shaped channels 37 with this pleat density and support structure configuration.
To assist in the spacing and structural integrity, various embossments 38 are provided to widen the pleat flanks at the select areas where the adhesive spacer beads 36 are laid down. This can be seen, for example, in
Referring to
However, it should be noted that preferably, additional structure such as an outer peripheral frame structure such as planar edge bands 50 may be laminated across the zig-zagging end faces 52 at opposing ends of the filter media pack 22 as shown in
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 flanks 34. 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 filter 10. 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 embossments 38 (grooves, folds or wrinkles extending between pleat tips 35 and between inlet and outlet faces) formed into the filter media and adhesive spacer beads 36 are illustrated on the filter media of filter media pack 22 as shown in
To better facilitate for structural integrity and high air flow, some preferred embodiments may include additional pleat supports and spacers between adjacent pleat flanks 34. 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).
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:
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 of
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.
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.
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.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, 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.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments 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 specifically described 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 otherwise indicated herein or otherwise clearly contradicted by context.
This patent application claims the benefit of U.S. Provisional Patent Application No. 61/736,658, filed Dec. 13, 2012, the entire teachings and disclosure of which are incorporated herein by reference thereto.
| Number | Date | Country | |
|---|---|---|---|
| 61736658 | Dec 2012 | US |
