Orifice-defining entry plate for filtration device

A filter unit for use With a filtrating fluid flow system is configured to receive a flow of a fluid containing particulate matter. The filter unit comprises a filter structure formed of a filter material configured to at least partially filter the particulate matter from the flow of fluid. The filter unit further comprises an entry plate located proximate the filter structure entrance. The filter structure and the entry plate together define a fluid cavity within the filter unit, the entry plate having at least one orifice defined therein through which the flow of fluid can pass into the fluid cavity. The orifice is configured to form a choke, creating a Venturi effect for temporarily increasing the velocity of the flow of fluid through the entry plate and within the fluid cavity, and onto the filter material.

BACKGROUND

Filtration systems are utilized in industrial, commercial, and residential settings for the physical separation of components of a fluid stream from the fluid stream. The fluid stream may comprise gaseous or liquid carrier fluids in which components to be filtered are transported. Filtration systems may employ filter units to physically remove the components to be filtered (e.g., paint droplets, dust particles, etc.) via impingement, interception, diffusion, straining and the like.

DETAILED DESCRIPTION

Overview

Filter units used in fluid flow system with a filtration system (i.e., filtrating fluid flow systems) have historically suffered from problems such as, for example, surface loading, high pressure drops, short lifespans, and/or complex attachment of a corresponding support frame. A filter unit's lifespan is determined by a given fluid handling (i.e. flow) system's designed capability to overcome the pressure drop through a filter unit. This pressure drop is continually increasing because of components in the fluid stream (e.g., particulates) that are captured in the filter unit. Therefore, a filter unit will need to be cleaned or replaced when the pressure drop across the filter unit has increased to the fluid handling system's design capability.

One existing filter unit, for example, consists of a flat, generally planar piece of filter media (i.e. filter pad) positioned in the fluid steam of a fluid handling system such that the fluid containing particulates must pass through the filter pad. Such a filter pad has a shorter lifespan due to its minimal amount of media that results in higher pressure drop and lower loading capacity. Another existing filter unit, commonly known as a pocket or cube filter unit, incorporates a fully open, three-dimensional filter media structure (i.e., filter structure) and a structural frame member, commonly made from metal, that is sewn or otherwise permanently attached to the filter structure proximate the opening of the filter structure, with the structural frame member being used to maintain an open filter arrangement.

Without the structural frame member present the open filter arrangement may close or collapse, and the filter unit can thus fail to operate properly or as intended. Such a three-dimensional filter unit, as compared to a filter pad of the same media, has more of the same media and therefore lower pressure drop and higher loading capacity and thusly a longer lifespan. However, the incorporation of the structural frame in this arrangement is particularly production-intensive and thus costly to manufacture. Moreover, such filters units, held in an open state by permanently attached structural frames, are larger and more voluminous and thus costly to warehouse and to transport from a manufacturing location to a consumer location. Furthermore, filter units incorporating metal frames cannot readily use incineration as a disposal method.

The present disclosure is directed to a filter unit that in various embodiments is less expensive to manufacture because the structural frame is not permanently attached to the filter structure, is less expensive to warehouse and to transport because the filter structure is less voluminous when in a closed or collapsed configuration, can utilize incineration as a disposal method because materials such as cardboard and plastic, for example, instead of metal, can be used to provide the needed structural strength, and has a longer lifespan due to the Venturi effect created by an orifice(s) that results in increased fluid velocity, which improves the impingement mechanism of particulate filtration. Of the many mechanisms involved in the filtration of particulates from a fluid stream, impingement is most directly related to the velocity of the fluid stream, with a change in velocity directly changing the momentum of the particulates.

Momentum is the tendency of the particulates to travel in a straight line even if the fluid carrying the particulates changes direction. In a filter unit, the change in fluid flow direction occurs because the fluid is generally designed to flow around the structural materials (e.g., the individual fibers that make up a fibrous filter material) of a fluid permeable filter media. The momentum of the particulates increases the likelihood that the particulates can strike (i.e., impinge upon) the filter media structural materials and be captured (i.e. filtered). The captured particulates, however, can add restriction to the flow of fluid through the filter media, resulting in an undesirable increase in the pressure drop across the filter unit. Those same captured particulates become part of the filter media structure. This increase in the amount of occupied volume within the filter media structural materials improves the likelihood that additional particulates can be captured by the filter unit.

In some embodiments, the filter unit of the present disclosure includes a filter structure (e.g., formed of a fluid-permeable filter material, such as a batting, foam, fibrous structure, or combinations thereof (or the like) and an orifice-defining plate member (e.g., an entry plate or a wall of a filter-carrying box) located proximate the fluid flow entrance or opening of the filter structure, with the plate member and the filter structure together defining a three-dimensional fluid cavity therebetween. The entry plate may, for example, be fabricated of a generally nonporous material, such as cardboard, plastic, sheet metal, or another structural, substantially non-permeable, material. In some embodiments, the entry plate is made of an inexpensive, generally nonporous material (e.g., cardboard, plastic, a recycled structural material, etc.) to facilitate replacement thereof, as needed. The entry plate defines at least one orifice therein (e.g., square, rectangular, polygonal, circular, oval, irregular, combinations thereof, and so forth). In embodiments, the orifice may be centrally located (e.g., latitudinally, longitudinally, or both). In embodiments, the orifice may be off-center.

The presence of the orifice in the entry plate functions as a choke, creating a Venturi effect, which temporarily accelerates (i.e., increases velocity of) the flow of fluid through the orifice, into the fluid cavity and, subsequently to the filter structure. In embodiments, the orifice may be configured to promote the formation of eddy currents within the fluid cavity at locations away from the orifice. In this manner, the presence of the orifice creates a low-pressure, fluid recirculating zone within the fluid cavity, wherein a portion of the particulates to be removed from the fluid may precipitate onto the downstream surface of the entry plate, thereby extending the lifespan of the filter unit.

In embodiments, the increased velocity flow of fluid may be particularly directed to impact on only a portion of the entire filter structure. In this manner, the enhanced impingement filtration mechanism resulting from the increased fluid velocity (e.g., increase in particulate momentum) deposits a greater portion of particulates on a smaller portion of the filter structure. Thusly, there are fewer particulates remaining to be filtered by the greater portion of the filter structure, resulting in a longer lifespan for the entire filter unit. That is, the non-particulate portion of the fluid flow can escape through the remaining portions of the filter structure not clogged by particulates. In embodiments, the portion of the filter structure impacted by the fluid stream (e.g., flow of fluid) may be generally in line with the corresponding orifice.

The entry plate may be a flat, generally planar member or may include one or more angled faces. In an embodiment including one or more angled faces, the entry plate can be configured such that, upon insertion at the opening of the filter structure, the one or more angled faces slope inwardly toward the orifice and into the interior of the filter cavity. As the presence of an orifice inherently increases the initial pressure drop (e.g. resistance to fluid flow) across the filter unit, the presence of the one or more angled faces creates a smooth approach to the orifice (particularly relative to a flat entry plate) and lessens the resultant increase in initial pressure drop. In an embodiment, the presence of the one or more angled faces can further direct fluid flow through the orifice of the entry plate onto a portion of the filter structure less than the entirety of the total filter structure. For example, the angled face(s) may be in the form of an open truncated cone (e.g., used in conjunction with a circular orifice), an open truncated pyramid (e.g., used in conjunction with a square or rectangular orifice), or a smooth approach bell-shape, which results in a reduced amount of increase to the initial pressure drop.

In embodiments, the entry plate (e.g., orifice plate) can be retained within the filter structure. In an embodiment, the entry plate may be retained by a press fit (e.g., material of the filter structure is displaced to a degree by the entry plate, thereby surrounding one or more edges of the entry plate) or otherwise interlocking fit within the filter structure. In some embodiments, the press fit may be enhanced by providing shaped edging to the entry plate (e.g., scalloped or serrated edging around the perimeter of the entry plate) to promote engagement of the entry plate with the filter structure. In some embodiments, the filter structure may include one or more tabs extending from the main filter structure, and the entry plate may define one or more corresponding plate slots through which a respective filter structure tab may be inserted, thereby helping to retain the entry plate relative to the filter structure.

In embodiments, the filter structure tabs can be formed of filter material that may have otherwise been considered waste material upon formation of the filter structure and otherwise trimmed from the main filter structure (i.e., tab/slot system permits better utilization of material). In some embodiments, one or more additional mechanical fasteners (e.g., one or more clips, one or more clamps, one or more threaded fasteners, a hook and loop fastening system, stitching, stapling, tape, adhesive, etc., or combinations thereof) and/or an adhesive may be used, whether alone or in combination with other mentioned mechanical retention mechanisms. In some embodiments, the entry plate may include a mechanism for incorporating an optional Z-dimension support for a non-self-supporting filter structure, and, in some embodiments, the non-self-supporting filtration device may be in the form of a material (e.g., a fabric) configured to be drape-able.

In embodiments the entry plate (e.g., orifice plate) may be a permanent portion of the filter unit. In an embodiment, an entry plate may have multiple orifices. In an embodiment having one or more orifices, one or more filter structures may correspond to one or more orifices. In an embodiment, a permanent entry plate may provide slots to correspond with filter structure tabs for retention of the filter structure to the entry plate. In some embodiments, one or more permanent additional mechanical fasteners (e.g., one or more clips, one or more clamps, one or more threaded fasteners, a hook and loop fastening system, etc., or combinations thereof) and/or an adhesive may be used, whether alone or in combination with other mentioned retention mechanisms. In some embodiments, the permanent entry plate may include a mechanism for incorporating an optional Z-dimension support for a non-self-supporting filter structure, and, in some embodiments, the non-self-supporting filtration device may be in the form of a material (e.g., a fabric) configured to be drape-able.

Example Implementations

FIG.1illustrates an example embodiment of a filtrating fluid-flow system (e.g., an exhaust, ventilation, or other fluid flow system with a filtration system)100, in accordance with the present disclosure. The filtrating fluid-flow system100may, for example, be an exhaust booth used in conjunction with an industrial paint spray operation. The filtrating fluid-flow system100can include an evacuation hood102, an exhaust (e.g., ventilation or fluid flow) outlet104, and a plurality of filter units106. The evacuation hood102can carry (i.e., support) and/or include the exhaust outlet104and filter units106, with the exhaust outlet104being configured to be connected to a vacuum flow (“F”) (e.g., exhaust or ventilation flow). The vacuum flow F can promote movement of a fluid (e.g., a fluid flow, an airflow, an air-liquid mixture, etc.), including any liquid or solid particulates carried thereby, into the filter unit106, with the filter unit106being configured to capture and retain liquid and/or solid particulates (e.g., paint, dust, etc.) from the fluid flow, as the fluid (e.g., air, etc.) is drawn through the filter unit106and toward the exhaust outlet104. The vacuum flow F may be generated, for example, by an exhaust fan, blower, pump, etc. (not shown).

Each filter unit106as shown can define a pocket (e.g., open space) therein when held open. A filter unit106can act as a fluid flow filtration device and can generally include a filter structure108(e.g., made of a fluid-permeable filter material, such as a foam or a fibrous batting) and an entry plate110(e.g., made of a generally non-permeable material, such as cardboard or plastic), with the entry plate110defining at least one entry orifice112there though. The entry orifice112defines a choke through the entry plate110and can help promote a Venturi effect into the filter structure108. The entry orifice112may also be considered to be a nozzle opening through the entry plate110. In embodiments, the filter structure108can be an open-pocket filter. Further, in some embodiments, the filter structure108may employ a tab-and-slot connection with the entry plate110, as discussed later. A given filter structure108may define a filter entrance (e.g., a throat or filter opening)114at a first end thereof, leading into the interior fluid cavity “C” (e.g., pocket volume) of the filter structure108. In the embodiment shown, the filter structure108is illustrated to be in the form of an open triangular prism. This shape is beneficial in that it is very easy to construct. However, other shapes may be chosen for the filter structure108, depending on the implementation.

The entry plate110(e.g., orifice plate) can be constructed of a non-permeable, structural material. As shown, the entry plate110can be interlocked or otherwise retained within or against or in general relationship to, a corresponding filter structure108proximate the filter entrance114thereof. The entry plate110can be releasably retained in place, for example, by a releasable molding, a quick-release adhesive, a press (e.g., interference) fit, or a mechanical connector (e.g., one or more clips, one or more clamps, one or more threaded fasteners, tape, releasable adhesive, a hook and loop fastening system, etc., or combinations thereof), or permanently retained in place, for example, by a permanent molding, a permanent adhesive, or a generally-permanent mechanical connection (e.g., stitching or stapling).

The entry plate110may accordingly serve to keep the filter entrance114open and retain the overall working shape of the corresponding filter structure108(e.g., by keeping the pocket structure open), which may otherwise be prone to collapse upon exposure to the vacuum flow F and/or to the collection of particulates within the filter structure108. Thus, the entry plate110can help provide shape and/or structure to an otherwise substantially non-self-supporting filter structure108. The entry plate110, per the embodiment shown inFIG.1, may be planar in shape. However, as will be described and shown hereinafter, the entry plate110may include one or more angled faces or may define additional structure (e.g., sides extending from the main planar portion; part of a box configuration). The entry plate110may further include reinforcing features (e.g., ribs; embedded elements) to promote the stiffness thereof. In the embodiment shown inFIG.1, each filter structure108has a corresponding entry or orifice plate110. However, as will be further described herein, it is contemplated that a single entry plate110may be provided with multiple orifices (e.g., for a plurality of filter structures; for multiple airflow passages to a given filter structure).

The filter structure108and the entry plate110together define a fluid cavity C (e.g., an open pocket) within the filter unit106. In some embodiments, the fluid cavity C and the entry orifice112are configured such that the flow of fluid entering the fluid cavity C through the entry orifice112can be constricted and accelerated into an increased-velocity fluid stream. That is, the entry orifice112can serve as a choke through the entry plate (e.g., orifice plate)110, resulting in a higher velocity fluid stream in the fluid cavity C and into the filter structure108. In embodiments, the filter structure108may maintain the constriction of the fluid stream upon passing through the entry orifice112, for example, by narrowing in cross-section relative to its depth (e.g., seeFIGS.5A,11A). In some embodiments, the filter structure108may form an open triangular prism shape (e.g.,FIGS.5A,5B), an open trapezoidal prism (e.g., truncated pyramid) shape (e.g.,FIGS.11A,11B), or some other narrowing prismatic shape (e.g.,FIG.14A).

In some embodiments, the acceleration may be such that the increase in the velocity of the fluid flow from a position just upstream of the filter unit106to a position inside the filter unit106, at which the flow is constricted to its minimum size (due to passing through a choke (e.g., constriction point)), may be 200% or more and can be in the range of 600 to 800%. In some embodiments, the fluid cavity C may be sufficiently large to permit the constricted flow to begin to re-expand within the fluid cavity C. In some embodiments, the fluid cavity C may be sufficiently large for low-pressure eddy currents E, as shown inFIGS.5A and5B, to develop outside the constricted flow AV(e.g., the constricted fluid flow AVresulting from a Venturi effect, perFIGS.5A and5B). In some embodiments, the fluid cavity C may be sufficiently small (e.g. the distance from the orifice112exit to the impact point on filter structure108(i.e., the depth of the fluid cavity C) and/or the available cross-section within the fluid cavity C) and/or may narrow in cross-section relative to the depth thereof (e.g., seeFIG.5A), so that the constricted flow stream cannot expand its velocity profile significantly within the fluid cavity C, thereby forcing a portion of the high velocity fluid stream (e.g., the constricted fluid flow AV) to impinge directly on the material forming the filter structure108. In embodiments, the impact velocity on the filter structure108is greater than a fluid-flow velocity prior to the flow passing through the entry orifice112. In some embodiments, the flow of fluid (e.g. the constricted fluid flow Av) can impact on only a portion of the total available filter structure108(e.g., a portion generally in line with the one or more entry orifices112). In some embodiments, narrowing of the cross-section of the filter structure108can be used to help guide the flow of fluid to impact on a desired portion of the total available filter structure108.

The entry plate110may, for example, be made of cardboard, plastic, wood, sheet metal, or any other material that is sufficiently non-permeable and/or nonporous to inhibit fluid flow through the entry plate material itself; and/or structurally rigid to provide, as needed, support to the filter structure108. The entry plate110may substantially limit fluid flow into the filter structure108to the path offered by the at least one entry orifice112of the entry plate110. The entry plate110, in some embodiments, may be made of a recycled and/or biodegradable material. The entry plate110may be a disposable/replaceable item upon use thereof. In some embodiments, the entry plate110may be made of a material capable of being disposed of by incineration (e.g., at temperatures in the range of 540-1200° C.) at currently available solid waste incineration facilities. In some embodiments, the entry or orifice plate110may be a permanent and/or reusable (e.g., cleanable) component of the filter unit106. In some embodiments the entry plate110may be built into the filtrating fluid-flow system100or may be a permanent part of the evacuation hood102. In some embodiments, the filter structure108may be reusable and/or cleanable, presuming the particulates filtered thereby can be adequately cleaned/removed therefrom to facilitate the reuse of the filter structure108. In some embodiments, the filter structure108may be a disposable/replaceable item upon use thereof.

Various embodiments for the filter unit, the filter structure, and the related entry plate are contemplated by the present disclosure. These embodiments are considered interchangeable, for example, with the filter unit106and/or its individual components for use in the filtrating fluid-flow system100, for example. As such, the filter unit and its related components are similarly numbered throughout, using a change in the first digit (e.g.,206,306,406) to denote the major embodiments. Similarly-numbered components can be expected to be similar in construction and material set forth with respect to the filter unit106, unless expressly set forth with respect to a given embodiment.

FIGS.2A through3Billustrate examples of the filter unit206.FIGS.2B and3Bcan each employ a filter structure208and a corresponding entry plate210. In one variant, as shown inFIGS.2A and2B, the entry plate210A can have a circular entry orifice212A defined there through. In another variant, as shown inFIGS.3A and3B, the entry plate210B can have a square entry orifice212B defined therethrough. However, entry orifices212having other shapes, as described herein, are contemplated.

With this example filter unit206, the entry plate210A,210B can be held within the filter entrance (e.g., filter throat)214of the filter structure208, for example, by an interference (e.g., press) fit, an adhesive, tape, or one or more mechanical fasteners (e.g., one or more clips, one or more clamps, one or more threaded fasteners, a hook and loop fastening system, stitching, stapling, tape, adhesive, etc., or combinations thereof). The entry plates210A,210B can have an outer shape that generally matches that of the filter throat214to promote a close fit therebetween (e.g., minimizing airflow entering the filter unit206at the juncture of the outer portions of the entry plates210A,210B and the filter throat214(also commonly known as a “bypass”); and promoting an interference (e.g., press) fit therebetween). The entry plates210A,210B may, for example, have flat/straight outer edges (e.g., for simplicity of design and manufacture; matching of shape of filter throat214).

FIGS.4A through4Dillustrate various stages of assembly of an example filter unit306. The filter unit306can include a filter structure308and an entry plate310. The filter structure308, in the illustrated embodiment, includes an opposing pair of tab extensions330, while the entry plate310(e.g., orifice plate) defines a plate orifice312and a pair of slots332, each on an opposed side of the plate orifice312. As can be seen fromFIGS.4C and4D, the tab extensions330can be folded and/or bent such that a portion thereof can be releasably retained within a corresponding plate slot332within the entry plate310, thereby helping to retain the entry plate310in position within the filter structure308. The tab-and-slot connection333, along with a press fit between the outer boundary of the entry plate310and a filter throat314of the filter structure308, can be sufficient to retain the entry plate310in place, potentially avoiding a need for any additional attachment mechanisms therebetween and allowing a user to readily switch out the filter structure308from the entry plate310, as needed.

As shown inFIG.4A, the entry plate310, in some embodiments, may also include a scalloped or serrated outer edge334. The scalloped or serrated outer edge334may be employed, as needed, to improve engagement with the corresponding filter throat314. While shown with a scalloped, serrated, or wavy outer edge334, it is to be understood that a flat edging or other similar edging may be employed and be within the scope of the present system. Likewise, it is to be understood that the use of a scalloped, serrated, wavy, or the like patterning for the outer edge334can be employed in other embodiments of the filter unit.

FIGS.5A and5Billustrate an example fluid flow (e.g., constricted upon entry through the flow choke point offered by the plate orifice312) that may be provided when employing the filter unit306, as well as the expected attachment (e.g., tab and slot; outer edging) arrangement associated with the filter unit306.FIG.5Ais a cross-sectional view relative to the generally triangular (e.g., “V” shaped cross section relative to the filter opening) profile of an embodiment of the filter unit306. Meanwhile,FIG.5Bis a cross-sectional view taken orthogonal (along5B-5B inFIG.5A) relative to the view used forFIG.5A.

In an embodiment, a vacuum (e.g. lower pressure) is created (e.g. by a fan, blower, pump, etc., not shown) downstream of filter unit306, causing fluid to flow through filter unit306in the direction generally indicated by arrow “F” (i.e., the flow direction). The construction of the filter structure308and the entry plate310of the filter unit306can produce, in general, at least four distinct fluid flow sections (as represented inFIGS.5A and5B): an external fluid flow AE, having velocity VEand pressure PE; a Venturi-effect constricted fluid flow AV, having a velocity VVand pressure PV; an eddy current section E, having pressure PEC; and the downstream vacuum flow section F, having a velocity VFand pressure PF(e.g., the four sections defining the entirety of the filter unit306fluid flow zone). For simplicity, and the purpose of this example, the cross-sectional areas for fluid flow are the same for fluid flows AEand F. Therefore, the Law of Mass Conservation as applied to fluid mechanics states that the external fluid velocity, VE, is generally equal to the vacuum fluid velocity, VF, and that the velocity of the constricted flow, VC, is higher than either VEor VF.

Essentially, the choked flow created at the plate orifice312is able to induce an increase in velocity in the fluid flow and the particulates carried within this fluid flow. This increased velocity means greater momentum of the fluid stream. Momentum describes the tendency of mass (e.g., fluid/particulates) to continue moving in a straight line at the given velocity. Because of momentum, the fluid stream exiting the orifice cannot instantaneously change velocity and direction and tends, therefore, to continue, over a distance, as constricted fluid flow AVhaving pressure PV. (It should be noted that, although not instantaneous and as represented by streamlines inFIGS.5A and5B, once constricted fluid flow AVexits the physical confines of plate orifice312, fluid flow AVwill begin to expand and slow and, given sufficient distance, transition completely into vacuum flow F having fluid velocity VF, which is less than constricted velocity VV).

The constriction of fluid flow AVfurther results in a lower pressure (PEC) void in eddy current section E. PECbeing lower than PVinduces a portion of the particulate-carrying constricted fluid to draw away from the constricted fluid flow section, AV, and circulate (i.e. swirl) within filter structure308as eddy currents E. The swirling eddy currents E may deposit, via impingement and/or precipitation, a portion of the carried particulates onto the downstream side (i.e., the interior or fluid-cavity side) of entry plate310without increasing the pressure drop across filter unit306thereby increasing the lifespan of filter unit306. The constriction of fluid flow AValso consolidates the particulates within the fluid into the smaller flow area AV. Furthermore, the increase in momentum can improve the impingement mechanism of particulate filtration, wherein particulates strike and are captured by the materials of a fluid-permeable filter media (e.g. the individual fibers that make up a fibrous filter material). The result is a more concentrated flow of particulates in a fluid stream being acted upon in a fluid filtrating system having an improved impingement filtration mechanism.

In an embodiment as shown inFIGS.5A and5B, filter structure308is able to intercept the constricted flow AVat impaction zone336. The higher concentration of particulate capture created by constricting the fluid flow, in cooperation with the improved impingement mechanism resulting from the increased velocity/momentum in the constriction zone, deposits significant amounts of particulate in the impaction zone336. The deposited particulate can cause the pores of the fluid permeable filter media (within the impaction zone336) to ultimately close (i.e., clog). As these pores close, the constricted fluid flow tends to expand more abruptly, and the impaction zone can likewise enlarge. It is the designed presence of fluid cavity C that provides room for the impaction zone336to expand. As previously discussed, the constricted fluid flow has a higher velocity, and its carried particulates have greater momentum. Greater momentum increases the tendency of the particulate to continue in a straight line whereby a portion of these continuing particulates may impinge on the already closed portion of media in the original impaction zone instead of following the more abrupt direction change of the fluid. Therefore, an additional portion of the particulate is captured by impingement on this closed area leaving less particulate to effect closure of the remaining open pores. (That is, the non-particulate portion (e.g., air) of the fluid flow can escape through still-open pores within the filter structure308.) As a result, the lifespan of filter unit306is further increased. It is to be understood that such fluid dynamics can generally be expected to exist in other present embodiments of the filter unit, not just in the filter unit306.

FIGS.6A through7Btogether illustrate another example filter unit406. The filter unit406employs a filter structure408and an entry plate410. The entry plate410can include one or more angled faces440(e.g., acutely angled) that terminate at the plate orifice412of the entry plate410and slope inwardly into the interior (i.e., into the fluid cavity) of the filter structure408. The one or more angled faces440can help decrease the pressure drop across the entry plate410(due to a smoother and less turbulent transition of the fluid flow into and through the orifice412) than may otherwise occur without the presence of the angled faces440. Furthermore, the one or more angled faces440can provide a void upstream of the plate orifice412into which fluid (i.e., air) may enter, allowing for a Venturi effect at the plate orifice412to occur, even if the filter unit406is close to or even immediately adjacent the source location of the fluid flow to be filtered. Additionally, the use of the angled faces440effectively reduces the distance between the plate orifice412and the back (e.g., apex) of the filter structure408(i.e., the plate orifice412is in the interior of the filter structure408, instead of at the filter throat or opening414). Therefore, adding the angled faces440to reduce that distance between orifice412and impaction zone increases the probability that the high-velocity fluid stream AVcan impact upon the filter structure408well before the constricted flow AVtransitions into lower velocity vacuum flow F, even if a larger and/or deeper filter structure408is employed. In the illustrated embodiment, four angled faces440are employed and thereby defining a four-sided, truncated pyramid, leading to a square or rectangular-shaped plate orifice412. However, it is to be understood that other quantities of angled faces440may be employed, leading to a relatedly shaped orifice. For example, one angled face440, in the form of truncated cone, may be used to define a circular orifice (not shown). Alternatively, by way of example only, but not shown, five angled faces440may be used to create a truncated, pentagonal pyramid and defining a pentagonal orifice.

As previously stated, the one or more angled faces440can be angled at an acute angle442, shown inFIG.7B, (relative to an opening plane444extending across the entry plate410and opposite the plate orifice412). The acute angle442can be greater than 0 degrees and less than 90 degrees, and in some embodiments, the acute angle442may be in a range of fifteen to sixty-five degrees (15-65°). In some embodiments, the acute angle442may be chosen to promote one or more of the above-discussed benefits associated with having one or more angled faces440.

FIGS.8A and8B, in a manner similar toFIGS.5A and5B, illustrate an example filter unit506in use. The filter unit506is similar in construction to the filter unit406, except that it employs a tab(s)530and slot(s)532connection system, as first shown inFIGS.4A through4Das tab(s)330and slot(s)332. Thus, the filter structure508and the entry plate510are similar to the filter structure408and the entry plate410, respectively, except for the aforementioned tab-and-slot connection system. Similar toFIGS.5A and5B, the filter unit506in use under the effect of a vacuum (e.g., exhaust) creates, in general, at least four distinct fluid flow sections: external fluid flow AE, constricted fluid flow AV(e.g., fluid flow (e.g., air flow) displaying a Venturi effect), eddy current section E, and downstream vacuum flow section F. As can be seen by comparingFIGS.8A and8BtoFIGS.5A and5B, the angled-faces of filter plate510move the plate orifice512to a location deeper into fluid cavity C and therefore closer to impaction zone536of filter structure508.

The constricted fluid flow AVis essentially linear (due to its momentum), in the direction of arrow F, as it exits plate orifice512but is able to begin to gradually expand and slow and, given sufficient distance, can transition entirely into the vacuum flow F. As noted earlier, improvements in the impingement mechanism of filtration are achieved with higher velocities, suggesting a position of the plate orifice512very close to impaction zone536is generally desired. However, as also previously discussed, these same improvements in the impingement mechanism can promote the capture and retention of more particulates from the fluid stream, causing increased filter media pore closure and the subsequent degree of enlargement of the impaction zone536. Greater distances from the plate orifice512exit to the impaction zone536provide for additional enlargement of the impaction zone536. The choice of embodiment, either presented or anticipated, can depend on the variables associated with differing implementations. In all of the various embodiments where a fluid flow is discussed, it is to be understood that any fluid flow (e.g., air, paint or other liquid, liquid-solid mix, gas-liquid mix, gas-solid mix, etc.) may be similarly employed and be within the scope of the present system.

FIG.9is side, isometric illustration of a prototype version of the filter unit506.

FIG.10shows a series of graphs reflecting the pressure drop across a filter unit versus the amount of paint overspray particulate captured by that filter unit (relative to the weight of paint fed to an industrial spray gun) for a tested series of different filter units, both traditional ones and several of those of the present disclosure. All filter units of the present disclosure incorporated a flat entry plate arrangement (e.g., per the filter unit106,206,306) and are described as having a “Nozzle Plate” per the included legend. Filter units, having two different filter media or material (one filter media per filter unit), were tested. Filter media A is a commodity-grade, high-loft, nonwoven polyester that has two-dimensional (i.e. generally planar) inlet and exit surfaces and is 1″ thick, and Filter media B is Applicant's filter media which has a three-dimensional inlet surface and a two-dimensional exit surface. Furthermore, separate filter units of the present disclosure were tested having orifices of different shapes and different sizes. It is important to note that, per the test methodology employed, when the pressure drop across a filter unit reached 0.5 inches of water column, that filter unit was considered to have attained its usable limit (i.e. lifespan) and thus needed replacement, concluding the test of a given filter unit. This limit was chosen to reflect the design capability for a typical industrial paint booth-style fluid handling system. Accordingly, the more paint that can be sprayed (e.g., the resultant amount of overspray ultimately captured) before reaching that limit, the more effective a given filter unit is deemed to be. As it can be seen fromFIG.10, every filter unit of the present disclosure that was tested outperformed all traditional versions that were also tested.

Many other filter unit arrangements are anticipated, such as, for example, those illustrated inFIGS.11A through11C;12A through12D; and13A through13D. The filter unit606of the example embodiment ofFIGS.11A through11Chas a flat entry plate610(e.g., orifice plate) but has a generally cube-shaped pocket filter structure608. The filter unit706of the example embodiment ofFIGS.12A through12Dhas a double “V,” two-pocket filter structure708and a corresponding double-orifice entry plate710(e.g., each rectangular orifice corresponding to a respective pocket). The filter unit806of the example embodiment ofFIGS.13A through13Dhas a double “V,” two-pocket filter structure808and a corresponding quad-orifice entry plate810(e.g., each pocket having two plate orifices corresponding thereto). Even when two orifices are available per fluid cavity, as per the illustrated example, it is desired that each orifice create a unique, constricted fluid stream carrying particulate that impinges upon the filter structure walls, at a corresponding unique impaction zone, before the constricted flow stream can expand to full size.

The filter unit906of the example embodiment ofFIGS.14A through14Dcan include a filter structure908and a bell-shaped entry plate910. As best seen fromFIG.14D, the bell-shaped entry plate910can include a concavely-curved guide portion911A and an orifice extension portion911B, with the extended portion911B distally defining a plate orifice912(e.g., at a location opposite the concavely-curved guide portion911A). The concavely-curved (i.e., inwardly-curved) guide portion911A can promote a smooth fluid flow toward the extended portion911B. The orifice extension portion911B, in turn, can promote a laminar fluid flow prior to entry of the fluid through the plate orifice912and can help direct the fluid flow toward a desired impaction zone of the filter structure908. The smooth-approach bell shape may provide for a lower pressure drop across the entry plate. Additionally, the plate orifice912may be positioned further into the interior of the fluid cavity C (e.g. for even larger and/or deeper filter structure908) by way of orifice extension portion911B. It is to be understood that, in some embodiments of the bell-shaped entry plate910, an orifice extension portion911B may not be included, with the plate orifice912being, instead, defined by the concavely-curved guide portion911A (not shown). Likewise, it is to be understood that the use of an orifice extension portion911B can be employed in other embodiments of the filter unit.

FIGS.15A through15Ctogether illustrate an example embodiment of a filter unit1006(commonly known as a two-stage filter unit when applied in the traditional sense) that is similar to the filter unit406, except that the filter unit1006can also include a forward or primary (e.g., first-stage) filter structure1050, in addition to the secondary or rear filter structure1008(e.g., second-stage) and the angled-faced entry plate1010positioned therebetween. The primary filter structure1050may be mounted across the entry or orifice plate1010, such that any fluid flow (air or otherwise) can reach and thus pass through the primary filter1050prior to proceeding to the remainder of the filter unit1006(e.g., the orifice plate1010and the filter structure1008). It is understood that, in embodiments, the primary filter structure1050can advantageously be used in conjunction with an angled-face embodiment of entry plate1010due to the void (i.e. gap/spacing) existing therebetween into which fluid (i.e. air) may enter, allowing the Venturi effect to occur after the fluid has passed through the entirety of primary filter structure1050. In an alternate embodiment (not shown), which may be less advantageous, a close-proximity arrangement of the primary filter structure1050and a potential flat embodiment of entry plate1010may not create a sufficient void therebetween. An insufficient void may create a constricted flow AVat, in, or even before primary filter structure1050. The substantially non-permeable (e.g., substantially non-porous) material of the entry plate1010can restrict fluid flow to only those portions of primary filter1050in direct alignment with the orifice of entry plate1010, impeding substantially full use of the filtration potential of the primary filter1050.

FIG.16illustrates an exhaust or filtrating fluid-flow system1100that can include an evacuation room/hood1102, an exhaust or ventilation outlet1104, a plurality of filter units1106, and an evacuation room entry door1190. The construction and operation of the filtrating fluid-flow system1100is similar to that of the filtrating fluid-flow system100, except that there is a single entry plate1110for use with the plurality of filter structures1108. The entry plate1110has a plurality of plate orifices1112, at least one plate orifice1112(e.g., nozzle orifice) corresponding to a given filter structure1108. In an embodiment, the entry plate1110may be considered a permanent part of the filtrating fluid-flow system1100, both in terms of its mounting (e.g., adhesive and/or mechanical fastening chosen to be more rigorous and not necessarily for easy-release) and/or its expected durability. In an embodiment, the entry plate1110may form a structural wall of the filtrating fluid-flow system1100. In an embodiment, the filtrating fluid-flow systems100and1100may be designed, for example, as overhead systems or walk-in systems (e.g., with an entry door, e.g.,1190, to access the filter structures, as needed) and be within the scope of the present disclosure.

FIGS.17A and17Billustrates a filter unit1206in accordance with an example embodiment, the filter unit1206including a planar (e.g. flat) filter structure1208and a box-style entry plate1210. Instead of the filter structure1208having a pocket and defining its own fluid cavity, the filter structure1208of this embodiment is a generally planar filter structure (e.g., any various pad/panel, with or without additional three-dimensional features built in). To provide an orifice arrangement and related fluid cavity for promoting a Venturi effect in accordance with the present disclosure, the orifice plate1210of this embodiment can be in the form of an open box (e.g., including four side panels, along with the main orifice panel). The entry plate1210, like other variations thereof, can have an entry orifice1212defined therethrough to facilitate the accelerated (e.g., increased velocity) fluid stream to the filter structure1208. In another embodiment (not shown) the planar filter structure1208may be installed in a filtrating fluid-flow system similar to that of filtrating fluid-flow system1100by providing a mounting means for planar filter structure1208downstream and apart from single entry plate1110such that a sufficient fluid cavity is created therebetween to promote a Venturi effect in accordance with the present disclosure.

FIG.18A through18Ctogether illustrate an example embodiment of a filter unit1306(also commonly known as a two-stage filter unit when applied in the traditional sense) that is similar to the filter unit1006, except that the filter unit1306can also include an additional entry plate1310B positioned upstream of the primary (e.g., first-stage) filter structure1350, secondary filter structure1308(e.g., second-stage), and the angled-faced entry plate1310A positioned between primary filter structure1350and secondary filter structure1308. In an embodiment, wherein primary filter structure1350is a generally planar filter structure, an additional entry plate1310B may be a box-style entry plate similar to entry plate1210previously shown inFIGS.17A and17B. In an embodiment, entry plate1310B may have more than one plate orifice and may, for example, have four plate orifices1312B as depicted inFIG.18A.FIG.18Cis a cross-sectional view depicting two of the four plate orifices1312B dividing external fluid flow AEinto two of four constricted fluid flows AV1and AV2(AV3and AV4are not visible in this view). When plate orifices1312B have the same shape and size, it is expected that constricted fluid flows AV1, AV2, AV3, and AV4will have the same velocity VV1in each of the four resultant constricted flows and 25% of the total mass. The resultant momentum in these constricted fluid flows AV1, AV2, AV3, and AV4may suggest a different distance from the entry plate1310B to the primary filter structure1350when compared to an optional single plate orifice1312B (not shown), which may result in a single constricted fluid flow AV1. Different implementations can determine which options and which embodiments may be preferred.

FIGS.19A through19Dare a series of views of a filter unit1406employing a box structure1407that defines a single angle-face nozzle entry plate1410and an opposed box exit1411and that is configured for receiving a filter structure1408(e.g., a V-shaped filter pocket) therein. The box exit1411may define a generally open (e.g., 75-90% of available space open for airflow therethrough) exit wall, leaving enough of an exit border1413to retain the filter unit1406. The box structure1407(e.g., with six nominal sides) can further include a box top1415which may define a series of foldable flaps1417. The foldable flaps1417can facilitate the insertion of the filter structure1408into the box structure1407, while permitting the closure of the box structure1407(e.g., by being taped shut or otherwise held closed), upon inserting the filter structure1408thereinto. The box structure1407can provide additional support for the filter structure1408(e.g., helping to keep it aligned relative to the angle-face nozzle entry plate1410and the opposed box exit1411, even under added weight of filtered material—i.e., less prone to sagging) and may facilitate storage and/or shipping of the filter unit1406. While shown with an angle face nozzle, it is to be understood, that in some embodiments, the nozzle plate1410may incorporate a simple opening (e.g., a flat/two-dimensional nozzle or choke, as shown in other embodiments).

FIGS.20A through20Fare a series of views of a filter unit1506employing a box structure1507that defines a dual angle-face nozzle entry plate1510and an opposed box exit1511and that is configured for receiving a double “V,” two-pocket filter structure1508or, alternatively, a pair of single pocket filter structures (not shown) therein. The box exit1511may define a generally open (e.g., 75-90% of available space open for airflow therethrough) exit wall, leaving enough of an exit border1513to retain the filter unit1506. The box structure1507can further include a box top1515which may define a series of foldable flaps1517. The foldable flaps1517facilitate the insertion of the filter structure1508into the box structure1507, while permitting the closure of the box structure1507, upon inserting the filter structure1508thereinto. The box structure1507can provide additional support for the filter structure1508(e.g., helping to keep it aligned relative to the dual angle-face nozzle entry plate1510and the opposed box exit1511, even under added weight of filtered material—i.e., less prone to sagging) and may facilitate storage and/or shipping of the filter unit1506. While shown with a pair of angle face nozzles within the entry plate1510, it is to be understood, that in some embodiments, the nozzle plate1510may incorporate a set of simple openings (e.g., flat/two-dimensional nozzle) and/or may include more than two nozzle openings, as suggested by other embodiments.

It is to be understood that the present application is defined by the appended claims. Although embodiments of the present application have been illustrated and described herein, it is apparent that various modifications may be made by those skilled in the art without departing from the scope and spirit of this disclosure.