Debris Mitigation

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 63/665,582, filed Jun. 28, 2024, the substance of which is incorporated herein by reference.

FIELD

The present disclosure relates generally to debris mitigation and more specifically to debris mitigation via airflow and vacuum.

BACKGROUND

During the tissue web converting process, a small percentage of fibers becomes airborne due to various factors such as contact with roll surfaces, changes in direction, and transformations like embossing and cutting. This airborne dust disperses throughout the enclosed machine area and quickly settles on equipment surfaces due to gravity. This not only affects process reliability but also increases fire hazards and the risk of product contamination. To address these hygiene issues, converting lines are equipped with dust control systems. These systems are designed to capture airborne fibers using vacuum suction and transport them to a central collection point. However, the limited effective range of these dust control hoods results in airborne fibers settling on surfaces beyond the vacuum's reach. Especially in the key transformation including the rewinder, dust may be distributed on the floor and equipment surfaces inside the entire enclosure of the process equipment. The distribution of dust across the surface requires significant manual effort associated with machine downtime for cleaning this area which is significantly covered with dust across the entire area. A need, therefore, exists for a debris mitigation system.

The discussion of shortcomings and needs existing in the field prior to the present disclosure is in no way an admission that such shortcomings and needs were recognized by those skilled in the art prior to the present disclosure.

SUMMARY

Various embodiments solve the above-mentioned problems and provide methods and devices useful for mitigating debris, such as debris associated with nonwoven web converting equipment, including but not limited to sanitary tissue product (e.g., paper towels, toilet tissue, facial tissue, etc.) converting equipment.

Various embodiments relate to a debris mitigation system for mitigating debris, the system comprising sanitary tissue product converting equipment, a plurality of airflow sources, and a vacuum.

The vacuum may be disposed below at least one airflow source of the plurality of airflow sources. At least one of the plurality of airflow sources may be disposed at a ground level. At least one of the plurality of airflow sources may be disposed above equipment level. The vacuum may be disposed at a ground level.

An intake of the vacuum may be disposed across from an output of at least one of the airflow sources. The system may comprise a plurality of vacuums. The one or more vacuums may collect debris into a dust collection system. The plurality of airflow sources may be disposed to form an arc of airflow or debris directed toward the one or more vacuums.

At least one of the plurality of airflow sources may oscillate. At least one of the airflow sources may have an “on” and “off” cycle, selectively enabling the at least one airflow source to operate dependent upon certain stimuli, while other airflow sources run constantly. The plurality of airflow sources may create an overlapping air flow region. At least one of the plurality of vacuums may be disposed in the overlapping air flow region. A sanitary tissue web may be substantially free from direct airflow from the airflow source.

The sanitary tissue product converting equipment may be at least partially enclosed by an enclosure. The enclosure may be at least partially formed by at least one enclosing air flow region that hinders airborne debris from escaping a perimeter. The enclosure may be at least partially formed by a sheeting material, for example a plastic sheeting material.

According to various embodiments, a debris mitigation system may comprise sanitary tissue product converting equipment, an airflow source, a vacuum, and the airflow source may create an equipment cleaning zone, a fall zone, and a sweep zone. The cleaning zone may be formed by the airflow source directing air at the sanitary tissue product converting equipment. The fall zone may be, but need not be, substantially free from direct air flow. The sweep zone may be formed by a second airflow source directing air toward the vacuum.

These and other features, aspects, and advantages of various embodiments will become better understood with reference to the following description, figures, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of this disclosure can be better understood with reference to the following figures, which illustrate examples according to various embodiments.

FIG. 1A is a schematic side view of a debris mitigation system.

FIG. 1B is a schematic side view of sanitary tissue product converting equipment.

FIG. 1C is a schematic front view of sanitary tissue product converting equipment.

FIG. 2 is a schematic top view of a debris mitigation system.

FIG. 3 is a schematic top view of a debris mitigation system.

It should be understood that the various embodiments are not limited to the examples illustrated in the figures.

DETAILED DESCRIPTION

Introduction and Definitions

This disclosure is written to describe the invention to a person having ordinary skill in the art, who will understand that this disclosure is not limited to the specific examples or embodiments described. The examples and embodiments are single instances of the invention which will make a much larger scope apparent to the person having ordinary skill in the art. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by the person having ordinary skill in the art. It is also to be understood that the terminology used herein is for the purpose of describing examples and embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (for example, having the same function or result). In many instances, the term “about” may include numbers that are rounded to the nearest significant figure.

In everyday usage, indefinite articles (like “a” or “an”) precede countable nouns and noncountable nouns almost never take indefinite articles. It must be noted, therefore, that, as used in this specification and in the claims that follow, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a support” includes a plurality of supports. Particularly when a single countable noun is listed as an element in a claim, this specification will generally use a phrase such as “a single.” For example, “a single support.”

Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit (unless the context clearly dictates otherwise), between the upper and lower limit of that range, and any other stated or intervening value in that stated range, is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.

“Machine direction” (MD) refers to the direction of material flow through a process. In addition, relative placement and movement of material can be described as flowing in the machine direction through a process from upstream in the process to downstream in the process.

“Cross direction” (CD) refers to a direction that is generally perpendicular to the machine direction.

“Debris” refers to scattered remnants or fragments of materials, ranging from fine dust particles of varying sizes to larger pieces, including fibrous elements such as cellulose fibers. In the context of papermaking or processes that utilize or modify nonwoven webs from a papermaking process, debris may also contain other components like softeners or additives used in the production process. For example, debris comprising cellulose fibers, softeners, lotions, and/or additives may be produced in the process of unwinding preformed nonwoven webs and passing the webs through a converting process. During such a converting process, the fibrous web may become de-interlaced, meaning that cellulose fibers may be detached to create debris. Such debris may include larger, heavier fibrous components that fall and/or settle readily, as opposed to being entrained in air like fine dust. One way, nonlimiting way, to characterize debris is by the fall rate of the debris. It is to be appreciated that the fall rate of debris can depend on many factors, including the size of the debris, the movement of air around the debris. The debris associated with cellulose fibers in a converting process may, for example, have a fall rate of at least about 0.1 inch/sec (0.254 cm/s) to about 10 inch/sec (25.4 cm/s).

“Airflow source” refers to a device or mechanism that generates a flow of air. In the context of the mitigation system described herein, an airflow source may be a component that produces a controlled flow of air in a specific direction. This airflow may be utilized to move debris that has settled on surface, to prevent debris from settling on surface, or to direct and to move airborne or settled debris towards a vacuum for collection. The airflow source may be implemented using various devices such as blowers, fans, compressed air nozzles, or any other means capable of generating and directing a flow of air. The airflow sources may be positioned strategically around the equipment to create airflow regions that may prevent or remove dust build-up of guide the debris towards the vacuum and aid in its collection and removal.

FIG. 1A is a schematic side view and FIG. 2 is a schematic top view of a debris mitigation system 10 comprising sanitary tissue product converting equipment 100, resting on a floor 30 via supporting legs 14. The sanitary tissue product converting equipment 100 may include any equipment necessary to process a sanitary tissue web 15, including but not limited to a rewinder 101. FIG. 1B and FIG. 1C provide more details of the sanitary tissue product converting equipment 100, FIG. 1B being a schematic side view and FIG. 1C being a schematic front view of the sanitary tissue product converting equipment 100. It should be appreciated that the debris mitigation system 10 of the present disclosure may be use with various types of converting equipment 100 used in papermaking, including, but not limited to, a rewinder, an embosser, a laminator, an unwind stand, a combiner, a surface coater, etc.

The concept of “ground level” 31 may have various meanings depending on the specific configuration of the sanitary tissue product converting equipment 100. It is to be appreciated that sanitary tissue product converting equipment 100 may include a supporting frame 14 that may provide some separation between the ground 30 and a lower equipment level 12. The lower equipment level 12 may be defined as the height above the ground 30 of the lowest debris collecting surface 107 (See: FIGS. 1B and 1C) within the sanitary tissue product converting equipment 100. For example, the lower equipment level 12 may be associated with the top of a roller 104, a structural support member 105, a platform 106, a portion of a sanitary tissue web 15, or any other surface spanning the cross direction CD within the sanitary tissue product converting equipment 100. The supporting frame 14 may take any form, including walls or legs, or any other suitable means for holding the working equipment, such as rollers 104 off the floor 30. As used herein “ground level” may, but does not usually refer to an infinitesimally small plane associated with the ground, but rather to the space between the floor 30 and a lowest equipment point 102.

The concept of “equipment level” 13 is also useful according to various embodiments. An upper equipment level 11 may be at a plane that is parallel to the floor 30 and may coincide with the highest debris collecting surface 108 (See: FIGS. 1B and 1C) within the sanitary tissue product converting equipment 100. For example, the upper equipment level 11 may be associated with the top of a roller 104, a structural support member 105, a platform 106, a portion of a sanitary tissue web 15, or any other surface spanning the cross direction CD within the sanitary tissue product converting equipment 100. The “equipment level” 13 may be defined as the space between the upper equipment level 11 and the lower equipment level 12.

Referring again to FIG. 1A, debris 20 may be generated during the process. According to various embodiments, such debris 20 may be mitigated with a plurality of airflow sources 200 and at least one vacuum 300. The debris 20 may be collected into a dust collection system 600 via the at least one vacuum 300. The dust collection system 600 may include any equipment necessary to process the debris 20, including but not limited to a bag house 601, one or more drum filters 602, a compactor 603, and/or a cyclone separator 604. The vacuum 300 may have a suction zone 302 that extends beyond its intake 301, but the suction zone 302 may be inadequate to adequately collect the debris 20 generated by the sanitary tissue product converting equipment 100.

Each of the plurality of airflow sources 200 may comprise an output 201 to generate a flow of air in an airflow direction 202. The velocity of the flow of air in the airflow direction 202 at the output 201 may be in a range of from about 5 m/s to about 100 m/s, or about 10 m/s to about 95 m/s, or about 15 m/s to about 90 m/s, or about 20 m/s to about 85 m/s, or about 22 m/s, or about 25 m/s to about 80 m/s, or about 30 m/s to about 75 m/s, or about 35 m/s to about 70 m/s, or about 40 m/s to about 65 m/s, or about 45 m/s to about 60 m/s, or about 50 m/s to about 55 m/s. Airflow sources 200 in the equipment level 13 may impart the same velocity or a different velocity than airflow sources 200 above the upper equipment level 11 or airflow sources 200 at ground level. For example, a first airflow source 200 positioned at the equipment level 13 or above the equipment level may impart a velocity that is greater than, less than, or equal to a velocity imparted by a second airflow source 200 positioned at ground level 31. According to various embodiments, a first airflow source 200 positioned at or above the equipment level 13 may impart a velocity to the flow of air in the airflow direction 202 at the output 201 in a range of from about 5 m/s to about 20 m/s, or about 6 m/s to about 19 m/s, or about 7 m/s to about 18 m/s, or about 8 m/s to about 17 m/s, or about 9 m/s to about 16 m/s, or about 10 m/s to about 15 m/s, or about 11 m/s to about 14 m/s, or about 12 m/s to about 13 m/s, while a second airflow source 200 positioned at ground level 31 may impart a velocity to the flow of air in the airflow direction 202 at the output 201 in a range of from about 20 m/s to about 40 m/s. or about 21 m/s to about 39 m/s, or about 22 m/s to about 38 m/s, or about 23 m/s to about 37 m/s, or about 24 m/s to about 36 m/s, or about 25 m/s to about 35 m/s, or about 26 m/s to about 34 m/s, or about 27 m/s to about 33 m/s, or about 28 m/s to about 32 m/s, or about 29 m/s to about 31 m/s, or about 30 m/s.

Each of the plurality of airflow sources 200 may be independently oriented relative to a machine direction MD and a cross-direction CD, for example to be aligned with the machine direction MD or the cross-direction CD or to be disposed at an angle relative to the machine direction MD and/or relative to the cross-direction CD. For example, as shown in FIG. 2, some of the airflow sources 200 may be oriented at an angle 210 relative to the machine direction 210.

According to various embodiments, at least one of the plurality of airflow sources may have an air flow direction 202 disposed at an angle, such as the angle 210, of from about 0 degrees to about 180 degrees, or about 5 degrees to about 175 degrees, or about 10 degrees to about 170 degrees, or about 15 degrees to about 165 degrees, or about 20 degrees to about 160 degrees, or about 25 degrees to about 155 degrees, or about 30 degrees to about 150 degrees, or about 35 degrees to about 145 degrees, or about 40 degrees to about 140 degrees, or about 45 degrees to about 135 degrees, or about 50 degrees to about 130 degrees, or about 55 degrees to about 125 degrees, or about 60 degrees to about 120 degrees, or about 65 degrees to about 115 degrees, or about 70 degrees to about 110 degrees, or about 75 degrees to about 105 degrees, or about 80 degrees to about 100 degrees, or about 85 degrees to about 95 degrees, or about 90 degrees relative to a machine direction MD of the sanitary tissue product converting equipment 100. According to various embodiments it may be desirable for the sanitary tissue web 15 to be substantially free from direct airflow 202 from the airflow source 200.

The airflow sources 200 may be rigidly positioned. Alternatively, one or more of the airflow sources 200 may oscillate, for example about the machine direction MD, as illustrated in FIG. 2. The plurality of airflow sources 200 may be disposed to direct debris 20 toward the vacuum 300. For example, the plurality of airflow sources 200 may be disposed to form an arc 220 of airflow or debris directed toward the vacuum 300.

One or more of the plurality of airflow sources 200 may generate a flow of air in an airflow direction 202 to create one or more air flow regions 400. For example, as illustrated in FIG. 1A, an first airflow region 400a may created above the sanitary tissue product converting equipment 100, a second airflow region 400b may be created above the vacuum 300, and a third airflow region 400c may be created at ground level 31. Airflow regions 400 may or may not converge at one or more locations to form an overlapping airflow region 401. As illustrated in both FIG. 1A and in FIG. 2, one or more airflow regions 400 may form one or more enclosing air flow region 402 to guide the debris 20 toward the vacuum. Such enclosing airflow regions 402 may effectively form one or more portions of an enclosure 500 that bounds and/or constrains the debris 20 at least partially within a perimeter 510. In other words, the enclosure 500 may be at least partially formed by at least one enclosing air flow regions 402 that hinders airborne debris 20 from escaping the perimeter 510.

It is to be appreciated the other enclosures 500 may be employed to form such a perimeter 510, such as for example a sheeting material 520 that may be draped, hung, or positioned along the perimeter 510. The sheeting material 520 may be any suitable type of material including but not limited to a plastic 521. FIG. 1C shows that the enclosure 500 may subdivide the sanitary tissue product converting equipment 100 into multiple zones, including, for example, an operator zone 110, a process zone 111, and a transmission zone. The operator zone 110 may provide a safe, quiet, and relatively debris-free space for equipment operators to monitor the sanitary tissue product converting equipment 100. Debris may be contained within the process zone 111. Any airflow sources 200 or vacuums 300 may be positioned within the process zone 111. The transmission zone 112 may comprise equipment such as motors 113 to drive the rollers 104 within the process zone.

Referring again to FIG. 1A, the plurality of airflow sources 200 may be positioned to create airflow regions 400 that cooperate to remove debris 20 from a debris zone 700 and deliver it to the vacuum 300. For example, the plurality of airflow sources 200 may be positioned to create airflow regions 400 that define at least one cleaning zone 701, at least one fall zone 702, and at least one sweep zone 703. Within a cleaning zone 701 the debris 20 may be pushed or lifted off of the sanitary tissue product converting equipment 100 or structures within the sanitary tissue product converting equipment 100, including but not limited to rewinders 101, rollers, 104, structural support members 105, and/or platforms 106. After optionally moving through an arc 220, the debris 20 may enter a fall zone 702, where downward motion toward the floor 300 predominates. According to various embodiments, a fall zone 702 may be substantially free from direct air flow 400. Alternatively, at least one of the plurality of airflow sources 200 may direct air flow 400 in a downward direction through a fall zone 702 toward the floor 30. In either case, once at ground level 31, the debris may be swept or pushed through a sweep zone 703 across the floor 30 toward the vacuum. It is to be appreciated that a sweep zone 703 may formed by a second airflow source 200 directing air toward the vacuum 300.

Although, FIG. 1A shows a cleaning zone 701, a fall zone 702, and a sweep zone 703 positioned primarily outside of the sanitary tissue product converting equipment 100, with the exception of a portion of the sweep zone 703 that is below the sanitary tissue product converting equipment 100, it is to be appreciated that one or more of each of these zones may be created inside or outside of the sanitary tissue product converting equipment 100. For example, FIG. 1B shows multiple cleaning zones 701, multiple fall zones 702, and one sweep zone 703. The cleaning zones 701 clean debris from support members 105, from a rewinder 101, and from a platform 106. Multiple fall zones 702 may be created to move the debris 20 ultimately to the ground level 31 where it may be swept toward a vacuum 300 via the sweep zone 703. FIG. 1B also demonstrates that a plurality of arcs 220 may be created within the sanitary tissue product converting equipment.

As shown in FIG. 3, one or more vacuums 300 may be positioned at any location in or around the sanitary tissue product converting equipment 100. The plurality of airflow sources 200 may be positioned as appropriate to create the desired cleaning zone 701, fall zone 702, sweep zone 703, and optionally the perimeter 510. FIG. 3 demonstrates that the air flow directions 202 of the plurality of airflow sources 200 do not need to be aligned with the cross-direction CD or the machine direction MD, but rather may be oriented at any angle with respect thereto. FIG. 3 also demonstrates that the movement of debris 20 from the debris zone 700 need not be limited to a single direction. The airflow sources 200 may be positioned anywhere in the three-dimensional space around the sanitary tissue product converting equipment 100.

FIG. 3 also demonstrates that oscillating airflow sources 200 may oscillate in synchronization. For example, a first airflow source 200a may oscillate between a first airflow direction 202a and a second airflow direction 202b, while a second airflow source 200b may oscillate between a third airflow direction 202c and a fourth airflow direction 202d. The first direction 202a may be aligned with, tangential to, or opposite to the third airflow direction 202c. The second direction 202b may be aligned with, tangential to, or opposite to the fourth airflow direction 202d. The oscillation of the airflow sources 200 may be synchronized to direct debris 20 toward different vacuums 300 to avoid overloading the vacuums 300. Again, it is to be appreciated that the airflow sources 200 may be positioned anywhere in the three-dimensional space around the sanitary tissue product converting equipment 100. It is also to be appreciated that the oscillation is not limited to a single plane; the airflow sources 200 may oscillate in any direction.

According to any of the embodiments described herein, any or all of the airflow sources 200 may optionally have an “on” and “off” cycle, selectively enabling the at least one airflow source to operate dependent upon certain stimuli. Combinations of selectively enabled airflow sources 200 and continuously enabled airflow sources 200 are possible. For example, when at least one airflow source 200 is selectively enabled while one or more other airflow sources 200 run constantly. The stimuli may include but are not limited to the operational state of the sanitary tissue product converting equipment 100 and/or the presence of debris 20. The presence of debris 20 may be detected automatically via a sensor or manually by a human operator. Additionally or alternatively, the one or more airflow sources 200 may be selectively enabled periodically after the passage of a predetermined time increment.

Each of the one or more vacuums 300 may have any desired suction flow rate, for example, a suction flow rate of from about 50 cubic feet per minute (CFM) to about 6000 CFM, or about 100 CFM to about 5000 CFM, or about 200 CFM to about 4000 CFM, or about 300 CFM to about 3000 CFM, or about 400 CFM to about 2000 CFM, or about 500 CFM to about 1500 CFM, or about 600 CFM to about 1400 CFM, or about 700 CFM to about 1300 CFM, or about 800 CFM to about 1200 CFM, or about 900 CFM to about 1100 CFM. As specified in the Test Methods below, the flow rate for a specific apparatus should be measured at the inlet or at the outlet of that apparatus. The suction flow rate of any of the one or more vacuums 300 should, therefore, be measured at the inlet of the one or more vacuums 300.

Each of the one or more vacuums 300 may exhibit a positive pressure working against the suction flow rate, which may be referred to as a static pressure loss or as static pressure. The static pressure may be in a range of from 1 to 30 inches of water, or less than about 20 inches of water.

Each of the one or more airflow sources 200 may have any desired airflow rate, for example, an airflow rate of from about 5 CFM to about 100 CFM, or about 10 CFM to about 90 CFM, or about 20 CFM to about 80 CFM, or about 30 CFM to about 70 CFM, or about 40 CFM to about 60 CFM, or about 50 CFM to about 50 CFM. As specified in the Test Methods below, the suction flow rate for any of the one or more airflow sources 200 should be measured at the outlet of the one or more airflow sources 200.

A ratio of airflow rate from the one or more airflow sources 200 to the suction flow rate from the one or more vacuums may be 1:20, 2:20, 3:20, 4:20, 5:20, 6:20, 7:20, 8:20, 9:20, 10:20, 11:20, 12:20, 13:20, 14:20, 15:20, 16:20, 17:20, 18:20, 19:20, or 1:1.

TEST METHODS

Linear Distances

Linear distances may be measured by any appropriate instrument, such as, for example only, a ruler, that is calibrated and capable of a measurement to the nearest 0.1 mm. Linear distances modified by the term “about” mean at least that the specified value may be +/−0.1 mm. In many cases, however, the term “about” may mean a broader range because a functionally equivalent range surrounding that value may be appreciated. Area measurements are made using the projected area of the article, as viewed orthogonally to the plane of the longitudinal and transverse axes, in square millimeters to the nearest 0.1 mm². Area measurements modified by the term “about” mean at least that the specified value may be +/−0.1 mm². In many cases, however, the term “about” may mean a broader range because a functionally equivalent range surrounding that value may be appreciated.

Angles

Angles may be measured by any appropriate instrument, such as, for example only, a protractor, angle finder, theodolite, clinometer, sextant, bevel protractor, goniometer, inclinometer, digital angle gauge, angle cube, optical square, tachymeter, autocollimator, vernier bevel protractor, engineer's square, that is calibrated and capable of a measurement to the nearest 0.1 degrees. Angles modified by the term “about” mean at least that the specified value may be +/−0.1 degrees. In many cases, however, the term “about” may mean a broader range because a functionally equivalent range surrounding that value may be appreciated.

Fall Rate

Fall rates may be measured by any appropriate instrument or set of instruments calibrated and capable of a measurement to the nearest 0.1 cm/s. For example, a fall rate may be measured using a video capture of an object, such as debris, falling or laster doppler velocimetry. The distance covered over time may be calculated. Fall rates modified by the term “about” mean at least that the specified value may be +/−0.1 cm/s. In many cases, however, the term “about” may mean a broader range because a functionally equivalent range surrounding that value may be appreciated.

Air Flow Velocity

Air flow velocity may be measured by any appropriate instrument, such as, for example only, an anemometer, pitot tube, hot-wire anemometer, ultrasonic flow meter, vane anemometer, laser doppler anemometer, thermal mass flow meter, rotating vane flow meter, cup anemometer, or thermal anemometer, that is calibrated and capable of a measurement to the nearest 0.1 m/s. Air flow velocity modified by the term “about” mean at least that the specified value may be +/−0.1 m/s. In many cases, however, the term “about” may mean a broader range because a functionally equivalent range surrounding that value may be appreciated. To measure the air flow velocity of an airflow apparatus or a suction apparatus, the air flow velocity should be measured at the inlet or at the outlet of the apparatus. A position “at the inlet” or a position “at the outlet” may be a position that is proximate to the inlet or the outlet. For example, “proximate” may be from greater than about 0 mm to about 20 mm from the inlet or from the outlet.

Static Pressure

Static pressure for a vacuum may be measured by any appropriate instrument, such as, for example only, a digital vacuum gauge, a capacitance manometer, a Pirani gauge, a thermocouple gauge, an ionization gauge, or a McLeod gauge, that is calibrated and capable of a measurement to the nearest 0.1 Torr (0.05 inches of water). Static pressure modified by the term “about” means at least that the specified value may be +/−0.1 Torr (0.05 inches of water). In many cases, however, the term “about” may mean a broader range because a functionally equivalent range surrounding that value may be appreciated.

Further Definitions and Cross-References

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”

Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

While particular embodiments of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.