Patent Description:
Air cleaners or dust collector devices sometimes use exhaust gas from a valve and pressure tank (reservoir) to back flush filters. Examples of such air filters assemblies are disclosed in, for example, <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>, <CIT>, <CIT>, <CIT> and <CIT> and Patent Publication <CIT>.

Effective cleaning of these filters requires that the exhaust jet fill the opening of the filter to be cleaned. In many implementations, the opening of the filter corresponds to the opening in the tubesheet, in which the filter is mounted. lmprovements in pulse cleaning filters are desirable.

The claimed invention is defined in independent claims <NUM> and <NUM> and relates to a filter element as defined in independent claim <NUM> and relates to a dust collector as defined in independent claim <NUM>. Preferred configurations of the claimed filter element are defined in dependent claims <NUM>-<NUM>. Preferred configurations of the claimed dust collector are defined in dependent claims <NUM>-<NUM>.

To improve in pulse cleaning of filters, a filter element is provided including a media pack of Z-media having first and second opposite flow faces and a side wall extending between the first and second flow face. A gasket is secured to the side wall. The gasket has a sealing portion and an attachment portion. The sealing portion has a flat surface at least <NUM>,<NUM> (one inch) long and is located between being planar with and <NUM>,<NUM> (<NUM> inches) recessed from the first flow face, inclusive.

In another aspect, a dust collector is provided including a housing with a dirty air inlet, a clean air outlet, and an interior; a tubesheet in the housing interior having a plurality of openings; a plurality of panel-style filter elements mounted in a respective one of the openings in the tubesheet; and a plurality of blowpipes, with each being oriented to direct a fluid pulse at a respective one of the panel-style filter elements. The filter elements include a media pack of Z-media, a gasket that is between planar with and <NUM>,<NUM> (<NUM> inches) recessed from the first flow face, in which the gasket forms a seal with the tubesheet. The blowpipes direct a pulse at an angle that is not normal to a plane of the openings in the tubesheet and not in line with a general direction of filtration flow through the filter element.

In another aspect, a method of cleaning a filter element installed in a dust collector includes providing a filter element, as mentioned above, and periodically pulsing a jet of gas into the downstream flow face to cause at least some particulate material on an upstream side of the Z-media to be removed from the Z-media.

Not all the features described herein must be incorporated in an arrangement for the arrangement to have some selected advantage, according to the present disclosure.

A dust filter or air cleaner system is depicted generally at <NUM> in <FIG>. The system depicted includes a housing <NUM> having a side wall panel <NUM> broken away to illustrate the arrangement of various portions of the assembly. An upper wall panel <NUM> has an inner wall surface <NUM>. In this embodiment, an air inlet <NUM> is positioned in the upper wall panel <NUM> so that the particulate-laden air or other fluid is introduced into an unfiltered (dirty) fluid chamber <NUM>. The unfiltered chamber <NUM> is defined by an access door <NUM>, the upper wall panel <NUM>, opposing side wall panels <NUM>, a tubesheet <NUM>, and a bottom surface <NUM> partially defining a collection area or hopper <NUM>. The bottom base panel or frame <NUM> is secured to the side wall panels <NUM> in a suitable manner.

As mentioned above, the tubesheet <NUM> is mounted in the interior of the housing <NUM>. The tubesheet <NUM> includes a plurality of openings <NUM>. Within each opening <NUM> is mounted an individual filter element, which in the illustrated embodiment, is a panel-style filter element <NUM>. By the term "panel-style filter element" it is meant an element with filter media in which, in general, fluid to the filtered flows through the filter element in a straight-flow thorough manner. For example, a panel-style filter element can be pleated media, depth media, fluted media, Z-media including a z-filter construction, or mini V-packs. By "Z-media", it is meant media having first and second opposite flow faces with a plurality of flutes, each of the flutes having an upstream portion adjacent to the first flow face (so that the first flow face is an inlet flow face, where air to be filtered flows in) and a downstream portion adjacent to second flow face (so that the second flow face is an outlet flow face, where filter air exits the element), selected ones at the flutes being open at the upstream portion and closed at the downstream portion, while selected ones of the flutes are closed at the upstream portion and open at the downstream portion. The flutes can be straight, tapered, or darted. The flutes extend between the inlet flow face and the outlet flow face. Examples of filter elements with Z-media are found in, for example, <CIT>; <CIT>; and <CIT>.

The term "z-filter construction" as used herein, is meant to refer to a filter construction in which individual ones of corrugated, folded or otherwise formed filter flutes are used to define sets of longitudinal filter flutes for fluid flow through the media; the fluid flowing along the length of the flutes between opposite inlet and outlet flow ends (or flow faces) of the media. Some examples of z-filter media are provided in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>;<CIT>; <CIT>; <CIT>; <CIT>; Des. <CIT>; Des. <CIT>; Des. <CIT>; Des. <CIT>; and, Des.

One type of z-filter media utilizes two specific media components joined together, to form the media construction. The two components are: (<NUM>) a fluted (typically corrugated) media sheet; and, (<NUM>) a facing media sheet. The facing media sheet is typically non-corrugated, however it can be corrugated, for example perpendicularly to the flute direction as described in <CIT>.

The fluted (typically corrugated) media sheet and the facing media sheet, together, are used to define media having parallel inlet and outlet flutes; i.e. opposite sides of the fluted sheet operable as inlet and outlet flow regions. In some instances, the fluted sheet and non-fluted sheet are secured together and are then coiled to form a z-filter media construction. Such arrangements are described, for example, in <CIT> and <CIT>. In certain other arrangements, some non-coiled sections of fluted media secured to flat media, are stacked on one another, to create a filter construction. An example of this is described in FIG. <NUM> of <NUM>,<NUM>,<NUM>.

Typically, coiling of the fluted sheet/facing sheet combination around itself, to create a coiled media pack, is conducted with the facing sheet directed outwardly. Some techniques for coiling are described in <CIT> and <CIT>, published <CIT>. The resulting coiled arrangement generally has, as the outer surface of the media pack, a portion of the facing sheet, as a result. In some instances a protective covering can be provided around the media pack.

The term "corrugated" when used herein to refer to structure in media, is meant to refer to a flute structure resulting from passing the media between two corrugation rollers, i.e., into a nip or bite between two rollers, each of which has surface features appropriate to cause a corrugation affect in the resulting media. The term "corrugation" is not meant to refer to flutes that are formed by techniques not involving passage of media into a bite between corrugation rollers. However, the term "corrugated" is meant to apply even if the media is further modified or deformed after corrugation, for example by the folding techniques described in PCT <CIT>.

Corrugated media is a specific form of fluted media. Fluted media is media which has individual flutes (for example formed by corrugating or folding) extending thereacross.

Serviceable filter element or filter cartridge configurations utilizing z-filter media are sometimes referred to as "straight through flow configurations" or by variants thereof. In general, in this context what is meant is that the serviceable filter elements generally have an inlet flow end (or face) and an opposite exit flow end (or face), with flow entering and exiting the filter cartridge in generally the same straight through direction. (The term "straight through flow configuration" disregards, for this definition, any air flow that passes out of the media pack through the outermost wrap of facing media. ) The term "serviceable" in this context is meant to refer to a media containing filter cartridge that is periodically removed and replaced from a corresponding air cleaner. In some instances, each of the inlet flow end and outlet flow end will be generally flat or planar, with the two parallel to one another. However, variations from this, for example non-planar faces are possible.

In general, the media pack includes appropriate seal material therein, to ensure there is no unfiltered flow of air through the media pack, in extension from front flow face (an inlet flow face) completely through and outwardly from opposite oval face (outlet flow face).

A straight through flow configuration (especially for a coiled media pack) is, for example, in contrast to serviceable filter cartridges such as cylindrical pleated filter cartridges of the type shown in <CIT>, in which the flow generally makes a turn as its passes through the serviceable cartridge. That is, in a <NUM>,<NUM>,<NUM> filter, the flow enters the cylindrical filter cartridge through a cylindrical side, and then turns to exit through an end face (in forward-flow systems). In a typical reverse-flow system, the flow enters the serviceable cylindrical cartridge through an end face and then turns to exit through a side of the cylindrical filter cartridge. An example of such a reverse-flow system is shown in <CIT>.

The term "z-filter media construction" and variants thereof as used herein, without more, is meant to refer to any or all of: a web of corrugated or otherwise fluted media secured to (facing) media with appropriate sealing to inhibit air flow from one flow face to another without filtering passage through the filter media; and/or, such a media coiled or otherwise constructed or formed into a three dimensional network of flutes; and/or, a filter construction including such media. In many arrangements, the z-filter media construction is configured for the formation of a network of inlet and outlet flutes, inlet flutes being open at a region adjacent an inlet face and being closed at a region adjacent an outlet face; and, outlet flutes being closed adjacent an inlet face and being open adjacent an outlet face. However, alternative z-filter media arrangements are possible, see for example <CIT>; also comprising flutes extending between opposite flow faces, with a seal arrangement to prevent flow of unfiltered air through the media pack.

In operation, fluid, such as air, to be filtered flows into the system <NUM> through the inlet <NUM>. From there, it flows through the filter elements <NUM>. The filter elements <NUM> remove particulate material from the fluid. The filtered fluid then flows into the clean air or filtered flow chamber <NUM>. From there, the clean air flows through an outlet <NUM>. Periodically, the filter elements <NUM> will be cleaned by pulsing a fluid jet, such as ajet of air, from a downstream side <NUM> of the filter element <NUM> to an upstream side <NUM> of the filter element <NUM>. Specifically, a jet of pressurized gas will be directed through individual blow pipes <NUM>, a respective blow pipe being oriented for each of the respective filter elements <NUM>. This will direct the jet through each filter element <NUM>, from the downstream (outlet) side <NUM> to the upstream (inlet) side <NUM>. This helps to knock debris and particulate from the upstream side <NUM> of the filter element <NUM>, directing it off the filter element <NUM> and into a hopper.

A schematic illustration of the portion of the system <NUM> is illustrated in <FIG>. In <FIG>, the blow pipe <NUM> can be seen oriented with respect one the filter elements <NUM> in the opening <NUM> in the tubesheet <NUM>. In <FIG>, it can be seen how the blow pipe <NUM> is oriented relative to the filter element <NUM> in a plane <NUM> (<FIG>) that contains the respective opening <NUM> in the tubesheet <NUM> for the respective filter element <NUM>, such that a pulse that comes from the blow pipe <NUM> is at an angle that is not normal to a plane of the opening <NUM> and is not in line with a general direction of filtration flow thorough the filter element <NUM>. By the term "not normal", it is meant non-orthogonal, such as at an acute or obtuse angle relative to the plane <NUM> that contains the opening <NUM> for the respective filter element <NUM>. By "not in line with a general direction of filtration flow", it is meant, for a straight-through flow filter, the pulse flow is in a direction that is not parallel to the flow of direction through the filter element <NUM>. By directing the fluid pulse at the filter element <NUM> at such an angle <NUM>, the exhaust jet, which expands at a predictable angle, creates a diameter D2 (<FIG>) larger in one direction that a diameter D1 that is typically used in the prior art.

While the illustrated embodiment shows only a single blowpipe <NUM> corresponding to a single filter element <NUM>, it should be understood that in many implementations, there are more than one blowpipe <NUM> for each element <NUM>.

In some embodiments, at least a portion of the pulse can be trapped by using an optional accumulator arrangement <NUM>. The accumulator arrangement <NUM> captures the flow of the pulse from the blow pipe <NUM>. In one embodiment, the accumulator arrangement <NUM> includes a least one plate, shown as first plate <NUM>, oriented on the clean air side <NUM> of the tubesheet <NUM> and adjacent to the opening <NUM> of the tubesheet <NUM>. The first plate <NUM> may be any type of wall, sheet metal, panel, baffle, rigid plastic, or generally non-porous solid structure that is oriented to the adjacent respective opening in the tubesheet <NUM> for the respective filter element <NUM>.

In certain implementations, the accumulator arrangement includes a second plate <NUM> oriented at an opposite end of the opening <NUM> at the tubesheet <NUM> from the first plate <NUM>. In the embodiment shown, the first and second plates <NUM>, <NUM> are aligned with the general direction of the pulse, but the angle does not necessarily need to be the same as the angle of the pulse direction. <FIG> illustrates a center line of the direction of the pulse at <NUM>. The first plate is mounted at a first angle <NUM> relative to the tubesheet <NUM>. The first angle is within about <NUM>° of center line <NUM> of a direction of the pulse. Similarly, the second plate <NUM> is mounted at a second angle <NUM> relative to the tubesheet <NUM>. The second angle <NUM> is within about <NUM>° of the center line <NUM> of a direction of the pulse. In some embodiments, the first angle <NUM> and the second angle <NUM> are equal. In other embodiments, the first angle <NUM>, and second angle <NUM> are unequal. In some embodiments, the first angle <NUM> and the second angle <NUM> are within <NUM>° of being parallel to each other. The angles <NUM>, <NUM> of the plates <NUM>, <NUM> are selected based upon the angle <NUM> of the pulse.

As illustrated in <FIG>, the first plate <NUM> has length L<NUM>, which is preferably no longer than three times the length of the respective opening <NUM> in the tubesheet <NUM>. This is because primary flow pressure loss increases with increase in length. Preferably, the length L<NUM> has a length that is between <NUM>-<NUM>% of a length of the respective opening <NUM> in the tubesheet <NUM>. In preferred embodiments, the blowpipe <NUM> is spaced no more than <NUM>-<NUM> times of an inside diameter of the blowpipe from the tubesheet to eject the pulse.

In <FIG>, reference numeral <NUM> shows the offset between the pulse center line <NUM> and a center of the filter element <NUM>. This shows how the center line <NUM> of the pulse is not always in alignment with the center of the filter element <NUM>.

In one embodiment, the plate that is closer to the respective blow pipe <NUM> (in the embodiment illustrated, the second plate <NUM>) has a length that is shorter than the other plate (in this example, the first plate <NUM>). In one embodiment, this shorter plate <NUM> has a length that is not less than <NUM> % of a length of the respective opening <NUM> in the tubesheet <NUM>. This arrangement is advantageous because of both material savings and pressure loss associated with pumping air flow.

Attention is directed to <FIG>. In <FIG>, the arrow <NUM> represents the prior art pulse direction. In the prior art, the standard pulse direction is directed perpendicular or normal to the plane <NUM> that contains the tubesheet <NUM>. Angle <NUM> shows the angle that is offset to the vertical direction, or the direction from the standard, prior art direction shown by arrow <NUM>. A typical pulse expansion is shown at angle <NUM>, from the blow pipe <NUM>. As explained above, the exhaust jet from the blow pipe <NUM> creates a diameter D2, covering a larger surface area in the opening <NUM> of tubesheet <NUM>, versus diameter D1 that comes from the exhaust jet shown at arrow <NUM> in the prior art arrangement.

One useful arrangement has the following angles and dimensions: Angle <NUM> is <NUM>°-<NUM>°, preferably <NUM>°; angles <NUM> and <NUM> are equal and <NUM>°-<NUM>°, preferably <NUM>°-<NUM>°; first and second plates <NUM>, <NUM> are parallel; offset <NUM> is about <NUM>,<NUM> (<NUM> inch); length L1 is about <NUM>,<NUM>-<NUM> (<NUM>-<NUM> inches), preferably about <NUM>,<NUM> (<NUM> inches); and length L2 is about <NUM>-<NUM> (<NUM>-<NUM> inches), preferably about <NUM>,<NUM> (<NUM> inches).

<FIG> depict useful embodiments for the filter element <NUM> in the collector housing <NUM>. Filter element <NUM> includes a media pack <NUM> of Z-media. The media pack <NUM> has first and second opposite flow faces <NUM>, <NUM> and a side wall <NUM> extending between the first and second flow faces <NUM>, <NUM>. In implementation, the first flow face <NUM> also corresponds to the downstream (outlet) flow face <NUM>, while the second flow face <NUM> corresponds to the upstream (inlet) flow face <NUM>.

In the embodiment shown, the media pack <NUM> includes a non-cylindrical pack of media that is a coiled construction <NUM>. In alternative embodiments, the media pack <NUM> can be a construction of stacked Z-media. The coiled construction <NUM> has an overall cross-sectional shape that can be oval or race track-shaped. In the embodiment shown, the media pack <NUM> is race track-shaped in that it has a pair of straight parallel sides <NUM>, <NUM> joined by rounded ends <NUM>, <NUM>. In other embodiments, the media pack <NUM> can be round or rectangular, or rectangular with rounded corners.

In general, the filter element <NUM> includes a handle member <NUM> extending axially from the first flow face <NUM>. In this embodiment, the handle member <NUM> includes a projection <NUM> defining an open aperture <NUM> sized to accommodate a human hand. The filter element <NUM> can be made generally in accord with <CIT>.

In this embodiment, the filter element <NUM> includes a central core <NUM> embodied as a flat board. The media pack <NUM> is coiled around the core <NUM>. The core <NUM> projects above the first flow face and defines the handle member <NUM> for manipulating the filter element <NUM>.

The filter element <NUM> further includes a gasket <NUM>. The gasket <NUM> is secured to the side wall <NUM>. In preferred implementations, the gasket <NUM> is molded directly to the side wall <NUM> of the media pack <NUM>. In other embodiments, the gasket <NUM> can be pre-made through, for example, an extrusion process and then attached to the side wall <NUM> of the media pack <NUM> by glue or an adhesive.

In accordance with principles of this disclosure, the gasket <NUM> is secured to the side wall <NUM> so that it is between planar with and <NUM> inches recessed from the first flow face <NUM>, inclusive. In other words, the gasket <NUM> is either completely even with (planar with) the first flow face <NUM> or it is located no greater than <NUM>,<NUM> (<NUM> inches) recessed away from the first flow face <NUM>, inclusive. By the term "inclusive" it is meant that the gasket <NUM> can be even with the flow face <NUM> or it can be <NUM>,<NUM> (<NUM> inches) recessed from the first flow face <NUM>, or it can be anywhere within the range of even with and <NUM>,<NUM> (<NUM> inches) recessed from the first flow face <NUM>. By locating the gasket <NUM> at this location, it positions the media pack <NUM> in the tubesheet <NUM> in a way that allows the downstream flow face <NUM> to be generally even with the tubesheet <NUM>. This results in more effective pulse cleaning of the filter element <NUM> because less energy is lost when the downstream flow face <NUM> is even with the tubesheet <NUM>.

In the embodiment shown, the gasket <NUM> has a sealing portion <NUM> and an attachment portion <NUM>. The attachment portion <NUM> is the part of the gasket <NUM> that is directly secured to the side wall <NUM> of the media pack <NUM>. The sealing portion <NUM> is the part of the gasket <NUM> that is compressed against the tubesheet <NUM> to form a seal with the tubesheet <NUM>.

In the embodiment shown, the sealing portion <NUM> has a flat surface <NUM>. The flat surface <NUM>, in practice, is at least one inch long. In <FIG>, it can be seen how the flat surface <NUM> is planar with the first flow face <NUM>. In the embodiment of <FIG>, the flat surface <NUM> is recessed a distance <NUM> from the first flow face <NUM>. This distance is not greater than <NUM>,<NUM> (<NUM> inches), inclusive.

In reference again to <FIG>, the gasket <NUM> defines an undercut <NUM> between the attachment portion <NUM> and the sealing portion <NUM>. As can also be seen in <FIG>, the sealing portion <NUM> includes a first angled surface <NUM> and a second angled surface <NUM>. The first and second angled surfaces <NUM>, <NUM> slant toward each other to meet an apex <NUM>. The first angled surface <NUM> and the attachment portion <NUM> are joined at a base <NUM>. The first angled surface <NUM> extends from the attachment portion <NUM> at the base <NUM> to the apex <NUM>, while the second angled surface <NUM> extends from the flat surface <NUM> to the apex <NUM>. The undercut <NUM> is defined as a gap between the first angled surface <NUM> and the attachment portion <NUM>. In the embodiment shown, the attachment portion <NUM> includes an extension that extends from the surface <NUM> down past the apex <NUM>.

In the embodiment shown, the undercut <NUM> is defined by a vertical distance <NUM> from the base <NUM> to the apex <NUM>, or end of the first angles surface <NUM> shown. This dimension <NUM> is at least <NUM> inch.

The flat surface <NUM> slopes downward and away from the first flow face <NUM> at an angle that is greater than zero degrees and less than <NUM> degrees.

In use, the element <NUM> is installed in dust collector <NUM> in a manner such that the downstream flow face <NUM> is even with the tubesheet <NUM> or is less than <NUM>,<NUM> (<NUM> inches) recessed from the tubesheet <NUM>, inclusive. The filter element <NUM> can be cleaned by periodically pulsing a jet of fluid or gas into the downstream flow face <NUM> to cause at least some particulate material on the upstream side <NUM> of the Z-media pack <NUM> to be removed from the media pack <NUM>.

A filter element can include a media pack comprising opposite first and second flow faces with flutes extending in a direction therebetween; a sidewall extending between the first and second flow faces; one of the first and second flow faces being an inlet flow face and the other being an outlet flow face; and a gasket secured to the sidewall; the gasket having a sealing portion and an attachment portion; the sealing portion having a flat surface at least <NUM>,<NUM> (one inch) long and being between planar with and <NUM>,<NUM> (<NUM> inches) recessed from the first flow face, inclusive.

The media pack may be racetrack shaped having a pair of straight parallel sides joined by rounded ends.

The gasket can define an undercut between the attachment portion and the sealing portion; the sealing portion can include first and second angled surfaces slanting toward each other to meet at an apex; the first angled surface can extend from the attachment portion to the apex; the second angled surface can extend from the flat surface to the apex; the undercut may be defined as a gap between the first angled surface and the attachment portion; and the first angled surface and the attachment portion may be joined by a base.

A vertical distance from the base to an end of the first angled surface can be at least <NUM>,<NUM> (<NUM> inches).

The flat surface may slope downward and away from the first flow face at an angle of greater than <NUM> degrees and less than <NUM> degrees.

The filter media may be a coiled construction.

A handle member may extend axially from the first flow face.

The handle member may include a projection defining an open aperture sized to accommodate a human hand.

A central core can be included, with the media pack coiled around the core.

The central core may project above the first flow face and define a handle member for manipulating the filter element.

A dust collector can include a housing including a dirty air inlet, a clean air outlet, and an interior; a tubesheet in the housing interior having a plurality of openings; a plurality of panel-style filter elements, each filter element being mounted in a respective one of the openings in the tubesheet; each of the filter elements including: a media pack comprising opposite first and second flow faces with flutes extending in a direction therebetween; a sidewall extending between the first and second flow faces; one of the first and second flow faces being an inlet flow face and the other being an outlet flow face; and a gasket secured to the sidewall; the gasket having a sealing portion and an attachment portion; the sealing portion having a flat surface at least <NUM>,<NUM> (<NUM> inch) long and being between planar with and <NUM>,<NUM> (<NUM> inches) recessed from the first flow face, inclusive; the gasket forming a seal with the tubesheet; a plurality of blowpipes; each blowpipe being oriented to direct a fluid pulse at a respective one of the panel-style filter elements at an angle that is: not normal to a plane of the openings in the tubesheet; and not in line with a general direction of filtration flow through the respective panel-style filter.

The media pack can be racetrack shaped having a pair of straight parallel sides joined by rounded ends; and the filter media is a coiled construction.

A central core can be included with the media pack being coiled around the core; and the central core can projects above the first flow face and defines a handle member for manipulating the filter element.

The gasket can define an undercut between the attachment portion and the sealing portion; the sealing portion including first and second angled surfaces slanting toward each other to meet at an apex; the first angled surface extending from the attachment portion to the apex; the second angled surface extending from the flat surface to the apex; the undercut being defined as a gap between the first angled surface and the attachment portion; and the first angled surface and the attachment portion being joined by a base.

A method of cleaning a filter element installed in a dust collector can include providing a filter element of z-media sealed against a tubesheet in a dust collector housing; the filter element having an inlet flow face and an outlet flow face with flutes in between and being sealed against the tubesheet so that the outlet flow face is between planar with and <NUM>,<NUM> (<NUM> inches) recessed from tubesheet, inclusive; and periodically pulsing a jet of gas into the outlet flowface to cause at least some particulate material on an upstream side of the z-media to be removed from the z-media.

Claim 1:
A filter element (<NUM>) comprising:
(a) a media pack (<NUM>) comprising opposite first (<NUM>) and second (<NUM>) flow faces with flutes extending in a direction therebetween; a sidewall (<NUM>) extending between the first (<NUM>) and second (<NUM>) flow faces; the first flow face (<NUM>) being an outlet flow face (<NUM>) and the second flow face (<NUM>) being an inlet flow face (<NUM>); and
(b) a gasket (<NUM>) secured to the sidewall (<NUM>); the gasket (<NUM>) having a sealing portion (<NUM>) and an attachment portion (<NUM>); the sealing portion (<NUM>) having a flat surface (<NUM>) at least <NUM>,<NUM> (one inch) long and being between planar with and <NUM>,<NUM> (<NUM> inches) recessed from the first flow face (<NUM>), inclusive; wherein the flat surface (<NUM>) slopes downward and away from the first flow face (<NUM>) at an angle of greater than <NUM> degrees and less than <NUM> degrees;
wherein:
(c) the gasket (<NUM>) defines an undercut (<NUM>) between the attachment portion (<NUM>) and the sealing portion (<NUM>);
(d) the sealing portion (<NUM>) including first and second angled surfaces (<NUM>, <NUM>) slanting toward each other to meet at an apex (<NUM>);
(e) the first angled surface (<NUM>) extending from the attachment portion (<NUM>) to the apex (<NUM>);
(f) the second angled surface (<NUM>) extending from the flat surface (<NUM>) to the apex (<NUM>);
(g) the undercut (<NUM>) being defined as a gap between the first angled surface (<NUM>) and the attachment portion (<NUM>); and
(h) the first angled surface (<NUM>) and the attachment portion (<NUM>) being joined by a base (<NUM>).