Patent Publication Number: US-2022221073-A1

Title: Flow fuse valve and method of assembly thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 63/137,510, filed Jan. 14, 2021, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to a flow fuse valve and a method of assembly thereof. 
     Flow fuses are used to interrupt fluid flow in the event of a downstream rupture in an associated fluid flow line with an accompanying substantial step-wise decrease in fluid pressure therein (herein referred to as a fluid flow short circuit). While existing flow fuses may be suitable for their intended purpose, the art of flow fuses would be advanced with a flow fuse construct that prevents washing out or displacement of a sealing member during a rapid change in fluid pressure associated with a fluid flow short circuit event. 
     BRIEF SUMMARY 
     An embodiment includes a flow fuse valve configured to be installed inline within a primary flow channel section having an interior wall, a first flow region, and a second flow region, the flow fuse valve having: a valve body; a poppet assembly disposed within the valve body, the poppet assembly having: a first poppet section; a second poppet section; a resilient seal member disposed and captured between the first poppet section and the second poppet section, wherein the first and second poppet sections are securely fastened with respect to each other subsequent to the resilient seal member being captured therebetween; and a resilient biasing member disposed between the first poppet section and the valve body that is configured to bias the poppet assembly toward an open-valve position; wherein the resilient seal member and the valve body are configured to form a fluid flow seal in response to the poppet assembly being disposed in a closed-valve position via an abrupt fluid pressure drop in the primary flow channel section downstream of the flow fuse valve, wherein the fluid flow is from the first flow region toward the second flow region. 
     An embodiment includes a method of assembling a fluid flow valve in accordance with the foregoing, the method including: providing a first poppet section; providing a resilient seal member; providing a second poppet section; assembling and securely fastening the second poppet section with the first poppet section, with the resilient seal member being captured between the first poppet section and the second poppet section, thereby providing a poppet assembly; providing a resilient biasing member; providing a valve body; installing the resilient biasing member and the poppet assembly into the valve body with the resilient biasing member captured between the valve body and the poppet assembly, the resilient biasing member being disposed and configured to bias the poppet assembly outward of the valve body; and fixedly restraining the poppet assembly relative to the valve body in an axial direction that prevents separation therebetween, with the resilient biasing member disposed therebetween. 
     The above features and advantages and other features and advantages of the invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the exemplary non-limiting drawings wherein like elements are numbered alike in the accompanying Figures: 
         FIGS. 1A and 1B  depict central longitudinal cross section views of an example flow fuse valve in an open position and in a closed position, respectively, in situ, in accordance with an embodiment; 
         FIG. 1C  depicts the central longitudinal cross section view of  FIG. 1A  with particular flow path detail enumerated, in accordance with an embodiment; 
         FIG. 1D  depicts a cross section view of the flow fuse valve depicted in  FIGS. 1A-1C , with associated Detail-B, but with the poppet assembly in a partially closed position, in accordance with an embodiment; 
         FIG. 2A  depicts an end view, as viewed from the side of the second flow region, of the flow fuse valve of  FIG. 1A , in accordance with an embodiment; 
         FIG. 2B  depicts a central longitudinal cross section view of the flow fuse valve of  FIGS. 1A and 2A  cut through section  2 B- 2 B of  FIG. 2A , in accordance with an embodiment; 
         FIG. 2C  depicts an axial cross section view through section cut  2 C- 2 C of  FIG. 2B , in accordance with an embodiment; 
         FIG. 2D  depicts an enlarged view of a portion of the cross section view of  FIG. 2B , in accordance with an embodiment; 
         FIGS. 2E and 2F  depict a cross section views of the poppet assembly of  FIG. 2B  prior to and subsequent to, respectively, the first and second poppet sections being fixated with respect to each other, in accordance with an embodiment; 
         FIG. 2G  depicts the cross section view of  FIG. 2B  with particular detail enumerated, in accordance with an embodiment; 
         FIG. 3A  depicts an end view, as viewed from the side of the second flow region, of the valve body of the flow fuse valve of  FIG. 2B , in accordance with an embodiment; 
         FIG. 3B  depicts a rotated isometric view of the valve body of  FIG. 3A , in accordance with an embodiment; and 
         FIG. 4  depicts a flow chart of a method of assembly, in accordance with an embodiment. 
     
    
    
     One skilled in the art will understand the drawings, described herein below, are for illustration purposes only. It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions or scale of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. 
     DETAILED DESCRIPTION 
     Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the appended claims. For example, where described features may not be mutually exclusive of and with respect to other described features, such combinations of non-mutually exclusive features are considered to be inherently disclosed herein. Accordingly, the following example embodiments are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention disclosed herein. 
     An embodiment, as shown and described by the various figures and accompanying text, provides a flow fuse valve  10  having a resilient seal member  300  disposed between a first poppet section  230  and a second poppet section  260  in such a manner as to prevent washing out or displacement of the sealing member  300  during a rapid change in fluid pressure associated with a fluid flow short circuit event. While the embodiment described herein depicts an O-ring as an exemplary sealing member  300 , it will be appreciated that the invention described in the appended claims may also be applicable to other sealing members of different cross-sectional shapes suitable for a purpose disclosed herein. 
     Reference is now made to  FIGS. 1A and 1B  that depict the flow fuse valve  10  in situ in open and closed positions, respectively. As depicted, the flow fuse valve  10  is configured to be installed inline within a primary flow channel section  50  having an interior wall  52 , a first flow region  54 , and a second flow region  56 , with an embodiment having a primary flow direction being from the side of the first flow region  54  toward the side of the second flow region/side  56 . However, it will be appreciated that another embodiment may be configured to have a primary flow direction being from the side of the second flow region  56  toward the side of the first flow region  54 . The flow fuse valve  10  may be threaded with, press-fit into, interference fit into with subsequent pin expansion, or otherwise attached to, the primary flow channel section  50 , which will be discussed further herein below. The flow fuse valve  10  has a valve body  100 , and a poppet assembly  200  disposed within the valve body  100 . The poppet assembly  200  includes a first poppet section  230  disposed on the side of the second flow region  56  of the valve body  100 , a second poppet section  260  disposed on the side of the first flow region  54  of the valve body  100 , a resilient seal member  300  disposed and captured between the first poppet section  230  and the second poppet section  260 , wherein the first and second poppet sections  230 ,  260  are securely fastened with respect to each other subsequent to the resilient seal member  300  being captured therebetween, and a resilient biasing member  400  disposed between the first poppet section  230  and the valve body  100  that is configured to bias the poppet assembly  200  toward an open-valve position as depicted in  FIG. 1A . The resilient seal member  300  and the valve body  100  are configured to form a fluid flow seal  102  in response to the poppet assembly  200  being disposed in a closed-valve position, as depicted in  FIG. 1B , via an abrupt fluid pressure drop in the primary flow channel section  50  downstream of the flow fuse valve  10  arising from a fluid flow short circuit event. The valve body  100  has a first flow portion  110  on the side of the first flow region  54 , and a second flow portion  130  on the side of the second flow region  56 , with at least one radial flow port  104  disposed therebetween (two opposing flow ports  104  depicted in the cross-section illustrations of  FIGS. 1A and 1B , and one of the two opposing flow ports  104  depicted in  FIG. 3B ). In an embodiment, the first poppet section  230  is axially restrained  60  in the open-valve position ( FIG. 1A ) via the second flow portion  130  of the valve body  100 , which in an embodiment is accomplished via a pliable retainer ring  600  securely disposed in a circumferential groove  236  of the first poppet section  230  that engages with an end  136  of the second flow portion  130  of the valve body  100  (best seen with reference to  FIG. 2B ). While  FIGS. 1A, 1B and 3B , depict and suggest two radial flow ports  104 , it will be appreciated that any number of flow ports for a purpose disclosed herein may be incorporated into the valve body  100 . In an embodiment, the at least one radial flow port  104  consists of two radial flow ports  104 . In an embodiment where the fluid flow is from the side of the first flow region  54  toward the side of the second flow region, a fluid screen  500  may be disposed upstream from the second poppet section  260  to screen out particulates that may inadvertently interfere with the operation of the valve sealing and shut-off function. In another embodiment where the fluid flow is from the side of the second flow region  56  toward the side of the first flow region  54 , a fluid screen  500  may be disposed upstream from the first poppet section  230  to screen out particulates that may inadvertently interfere with the operation of the valve sealing and shut-off function. In an embodiment where the fluid flow is from the side of the first flow region  54  toward the side of the second flow region  56 , the fluid screen  500  may be incorporated into a pin or screen insert  550  that may be expansion fit into or otherwise secured to (press fit or interference fit, for example) the first flow portion  110  of the valve body  100 . In an embodiment where the fluid flow is from the side of the second flow region  56  toward the side of the first flow region  54 , the fluid screen  500  may be incorporated into a pin or screen insert  550  that may be expansion fit into or otherwise secured to (press fit or interference fit, for example) the second flow portion  130  of the valve body  100 . In an embodiment, the flow fuse valve  10  may be threadably engaged with or otherwise secured to (press fit, or interference fit into with subsequent pin expansion, for example) the primary flow channel section  50 . 
     As depicted in  FIG. 1B , the fluid flow seal  102  is formed between the resilient seal member  300  and the valve body  100 , and is disposed within the first flow portion  110  of the valve body  100 . In an embodiment, the resilient seal member  300  is an elastomeric O-ring. In an embodiment, the fluid flow seal  102  is formed between the resilient seal member  300  and a conical internal surface  112  of the first flow portion  110  of the valve body  100 . 
     As depicted, and best seen with reference to  FIG. 2B , the resilient biasing member  400  is disposed between an undercut surface  234  of the first poppet section  230  and a shelf  138  of the second flow portion  130  of the valve body  100 . In an embodiment, the resilient biasing member  400  is a compression spring. In an embodiment, the resilient biasing member  400  traverses the at least one radial flow port  104 . 
     In an embodiment, the second poppet section  260  has an integrally formed circumferential rigid valve seat  262  (see  FIG. 1A ) having an outer diameter that is larger than an outer diameter of the resilient seal member  300 , such that in the closed-valve position ( FIG. 1B ) the valve seat  262  engages with the conical internal surface  112  of the first flow portion  110  of the valve body  100  to control a degree of compression of the resilient seal member  300 . 
     To provide for a self-centering poppet assembly  200  during a valve closing operation, the second flow portion  130  of the valve body  100  provides an axial guide for the poppet assembly  200  between the open-valve position ( FIG. 1A ) and the closed-valve position ( FIG. 1B ) with an elongated space (see internal flow channels  134 ,  FIGS. 2B and 2C ) therebetween that is sufficiently sized for the self-centering operation of the poppet assembly  200 . Stated alternatively, the poppet assembly  200  is substantially but not fully radially restrained by the valve body  100 , thereby permitting the poppet assembly  200  and the fluid flow seal  102  to self-center between an open-valve position ( FIG. 1A ) and a closed-valve position ( FIG. 1B ). In an embodiment, the elongated space between the second flow portion  130  and the poppet assembly  200  is provided by an inwardly facing surface  132  of the second flow portion  130  of the valve body  100  that includes the plurality of internal flow channels  134  (see also  FIGS. 2B and 2C ) adjacent the first poppet section  230  of the poppet assembly  200 . As depicted in  FIG. 2B , the plurality of internal flow channels  134  extend from the at least one radial flow port  104  to the end  136  of the second flow portion  130  of the valve body  100 . As also depicted in  FIG. 2B , the plurality of internal flow channels  134  are substantially void of the resilient biasing member  400 , with the second flow region end of the resilient biasing member  400  being disposed on the shelf  138  formed in the second flow portion  130  of the valve body  100  proximate the radial flow ports  104 . In an embodiment, the plurality of internal flow channels  134  are axially aligned with each other (see  FIGS. 2B and 2C  for example). In an embodiment, the plurality of internal flow channels  134  are linear flow channels axially aligned with a central axis of the primary flow channel section  50 . In an embodiment, the plurality of internal flow channels  134  have an axial cross-section profile with a hexalobular configuration of linear grooves, which in an embodiment is in accordance with the ISO 10664 standard. While a particular cross sectional profile of the plurality of internal flow channels  134  is depicted herein, hexalobular for example, it will be appreciated that other cross sectional profiles suitable for a purpose disclosed herein may be employed without detracting from a scope of an invention disclosed herein. Other example cross sectional profiles alternative to the hexalobular profile illustrated herein include but are not limited to: hexagon (true hexagon absent lobes), octagon, octa-lobular, square, square-lobular, pentagon, penta-lobular, triangle, tri-lobular, multi-spline, multi-lobular. As will be appreciated, the hexalobular cross sectional profile disclosed herein is but only one configuration that may be suitable for the internal flow channels  134 . As such, any and all cross sectional profiles for the plurality of internal flow channels  134  are contemplated, considered to be inherently disclosed herein, and therefore considered to fall within an ambit of the appended claims. 
     Reference is now made to  FIG. 2D  that depicts an enlarged view of the resilient seal member  300  disposed between the first poppet section  230  and the second poppet section  260 . In an embodiment, the first poppet section  230  has a first circumferential retaining surface  238  proximate the resilient seal member  300  and disposed at a first angle  239  relative to a datum  800  defined by an outer circumferential surface of the second poppet section  260 , and the second poppet section  260  has a second circumferential retaining surface  268  proximate the resilient seal member  300  and disposed at a second angle  269  relative to the datum  800 . In an embodiment, at least one of the first and second angle  239 ,  269  is an acute angle equal to or greater than 55-degrees and equal to or less than 80-degrees. In an embodiment, at least one of the first and second angle  239 ,  269  is an acute angle equal to or greater than 60-degrees and equal to or less than 75-degrees. In an embodiment, each of the first and second angle  239 ,  269  is an acute angle having an angular range as disclosed herein. As will be appreciated, each surface  238 ,  268  provides a half-dovetail groove or containment surface that serves to capture the resilient seal member  300  from being washed out or displaced during a valve closing event. 
     As can also be seen with reference to  FIGS. 2D, 2E and 2F , collectively, the two-part poppet assembly  200  of the first poppet section  230  and the second poppet section  260  consists of the first poppet section  230  being mechanically fixated with respect to the second poppet section  260 . In an embodiment, the first poppet section  230  has a bored out pocket  240 , which in an embodiment is a blind pocket, and the second poppet section  260  has a projection  266  disposed within the pocket  240 . With the resilient seal member  300  positioned proximate the second circumferential retaining surface  268 , the projection  266  of the second poppet section  260  is slidably inserted into the pocket  240  of the first poppet section  230  until stop surfaces at  205  on the first and second poppet sections  230 ,  260  engage each other, at which time the first and second poppet sections  230 ,  260  can be mechanically fixated with respect to each other in a manner disclosed herein to form the poppet assembly  200 . In an embodiment, the projection  266  has a circumferential groove  264 , and the mechanical fixation of the first poppet section  230  with respect to the second poppet section  260  is accomplished by swedging a portion of the first poppet section  230  into the circumferential groove  264  of the second poppet section  260 , depicted by swedged region  242  in  FIGS. 2D and 2F . 
     With reference now to  FIG. 3A  that depicts an axial cross section profile of the second flow portion  130  of the valve body  100 , the inwardly facing surface  132  of the second flow portion  130  of the valve body  100  has, in combination, partially an inner circular profile  140  and partially a plurality of integrally formed lobular profiles  142  that extend radially outward of the partial inner circular profile  140 , the combination of the partial inner circular profile  140  and the plurality of integrally formed lobular profiles  142  forming the plurality of internal flow channels  134 , where the first poppet section  230  has an outside diameter that is less than an inside diameter of the inner circular profile  140  (best seen with reference to  FIG. 2C  in combination with  FIG. 3A ). As can be seen with reference to  FIG. 3A , the inwardly facing surface  132  of the second flow portion  130  of the valve body  100  proximate the plurality of flow channels  134  includes the integrally formed lobular profiles  142  that are spaced apart from each other by circumferential segments  144  of the inner circular profile  140 . In an embodiment, the lobular profiles  142  are in the form of a hexalobular configuration, as observed and depicted in the axial cross section view of  FIG. 3A . 
     Reference is now made back to  FIG. 1A , in combination with  FIG. 1C , the second flow portion  130  of the valve body  100  is configured to provide an annular flow channel  58  between an outer surface of the second flow portion  130  and the interior wall  52  of the primary flow channel section  50 . In the open-valve position depicted in  FIGS. 1A and 1C , a fluid flow path  20  across the flow fuse valve  10  traverses: an axial path  22  within the first flow portion  110  of the valve body  100 ; then, an annular path  24  between the second poppet section  260  and the first flow portion  110  of the valve body  100 ; then, an annular path  26  between the resilient seal member  300  and the first flow portion  110  of the valve body  100 ; then, an annular path  28  between the first poppet section  230  and the conical internal surface  112 ; then, an annular path  30  between the first poppet section  230  and the first flow portion  110  of the valve body  100 ; then, a radial flow path  32  through the at least one radial flow port  104 ; and then, a first downstream flow path  34  that is an annular flow path between the second flow portion  130  of the valve body  100  and the interior wall  52  of the primary flow channel section  50 . As further depicted in the open-valve position in  FIG. 1C , the fluid flow path  20  across the flow fuse valve  10  further traverses a second downstream flow path  36  via the plurality of internal flow channels  134  (see also  FIG. 2B ) between the second flow portion  130  of the valve body  100  and the first poppet section  230  (see also  FIG. 1A ). In an embodiment, the second downstream flow path  36  is fluidly connected in parallel with the first downstream flow path  34 . 
     Reference is now made particularly to  FIG. 2B . In an embodiment, the first flow portion  110  of the valve body  100  has a bore  114  with an inside diameter ID- 1 , the first poppet section  230  has a circumferential stop-gap  232  having an overall outside diameter OD- 1 , where OD- 1  is sized to restrictively fit within ID- 1  such that the stop-gap  232  of the first poppet section  230  substantially restricts fluid flow through the bore  114  of the first flow portion  110  of the valve body  100  when the flow fuse valve  10  is in a closed-valve position ( FIG. 1B ). 
     From the foregoing it will be appreciated that in response to the flow fuse valve  10  transitioning from an open-valve position depicted in  FIG. 1A  to a closed-valve position depicted in  FIG. 1B , with a partially closed position depicted in  FIG. 1D , the flow fuse valve  10  is so configured such that: as the valve seat  262  of the poppet assembly  200  travels toward the conical internal surface  112  of the valve body  100 , the circumferential stop-gap  232  of the first poppet section  230  enters into the bore  114  of the first flow portion of the valve body  100  to restrict fluid flow through the bore  114 , followed by the resilient seal member  300  engaging with the conical internal surface  112  to establish a seal to fluid flow through the bore  114 , followed by the valve seat  262  engaging with the conical internal surface  112  to control compression of the resilient seal member  300 . While not being held to any particular theory, it has been found that such a restrictive fit between the stop-gap  232  and the bore  114  during an open-to-close action of the flow fuse valve  10  is effective in reducing the velocity of fluid flow at the point of valve closure to assist in preventing the washing out or displacement of the resilient seal member  300 . Additionally while not being held to any particular theory, it has been found that the combination of the radial flow ports  104  and the internal flow channels  134 , with the internal flow channels  134  being substantially void of the resilient biasing member  400 , provides for enhanced closing and sealing action of the flow fuse valve  10  in response to a fluid flow short circuit event. 
     In view of the foregoing description and accompanying illustration of structure of the flow fuse valve  10 , and with reference particularly to  FIG. 2G  and  FIG. 4 , it will be appreciated that a method  700  of assembling the fluid flow valve  10  includes: providing  705  a first poppet section  230 ; providing  707  a resilient seal member  300 ; providing  710  a second poppet section  260 ; assembling  715  and securely fastening  720  the second poppet section  260  with the first poppet section  230 , with the resilient seam member  300  being captured between the first poppet section  230  and the second poppet section  260 , thereby providing a poppet assembly  200 ; providing  722  a resilient biasing member  400 ; providing  725  a valve body  100 ; installing  730  the resilient biasing member  400  and the poppet assembly  200  into the valve body  100  with the resilient biasing member  400  captured between the valve body  100  and the poppet assembly  200 , the resilient biasing member  400  being disposed and configured to bias the poppet assembly  200  outward of the valve body  100 ; and, fixedly restraining  735  the poppet assembly  200  relative to the valve body  100  in an axial direction that prevents separation therebetween, with the resilient biasing member  400  disposed therebetween. 
     In an embodiment, the step of assembling  715  and securely fastening  720  the second poppet section  260  with the first poppet section  230  involves slidably inserting the projection  266  of the second poppet section  260  into the pocket  240  of the first poppet section  230 , and swedging a portion of the first poppet section  230  into the circumferential groove  264  of the second poppet section  260 , thereby mechanically fixating the first poppet section  230  with respect to the second poppet section  260 . 
     In an embodiment, the fixed restraint of the poppet assembly  200  relative to the valve body  100  in an axial direction, only one axial direction, is accomplished by installing a pliable retainer ring  600  in a groove  236  of the first poppet section  230  such that the retainer ring  600  engages with an end  136  of the second flow portion  130  of the valve body  100  under the influence of the resilient biasing member  400  biasing the poppet assembly  200  outward of the valve body  100 . 
     In an embodiment where fluid flow is from the first flow region  54  toward the second flow region  56 , the method  700  further includes assembling a fluid screen  500  with respect to the valve body  100  upstream from the second poppet section  260  to screen out particulates that may inadvertently interfere with the operation of the valve sealing and shut-off function. As described herein above, the fluid screen  500  may be incorporated into a pin or screen insert  550 . 
     Reference is now made to  FIGS. 1A, 1B  and  FIG. 2G , where  FIGS. 1A, 1B  depict a screen  500  and pin  550  assembly  560  fully inserted into the valve body  100 , and  FIG. 2G  depicts the screen  500  and pin  550  assembly  560  only partially inserted into the valve body  100 . To fully insert the pin/screen assembly  560  into the valve body  100  the insert principle is employed, which is described in the Lee Co. IMH Handbook available online at www.leeimh.com. In summary, the insert principle uses a pin, such as pin  550 , to expand a grooved section  570  (best seen with reference to  FIG. 2G ) of an insert, such as the valve body  100 , or more particularly the first flow portion  110  of the valve body  100 , into a housing wall, such as the housing wall of the primary flow section  50 , where the expansion fit serves to secure the valve body  100 , and therefore the flow fuse valve  10 , in the primary flow section  50 . An insert tool (not shown but described in the aforementioned Lee Co. IMH Handbook) may be used to properly seat the pin/screen assembly  560  into the valve body  100 . While an embodiment is depicted herein having a pin/screen assembly  560  having both a screen  500  and a pin  550 , it will be appreciated that the screen  500  may be omitted leaving just the pin  550  to be used in an expansion fit matter to secure the flow fuse valve  10  in the primary flow section  50 . 
     By providing a two-part poppet assembly  200  having the resilient seal member  300  disposed and captured between the first poppet section  230  and the second poppet section  260  as disclosed herein provides for installation of the resilient seal member  300  within the flow fuse valve  10  without the need to stretch or over-stretch the resilient seal member  300  over an outer diameter of the first or second poppet sections  230 ,  260  that are greater than an inner diameter of the resilient seal member  300 , which in an embodiment is an O-ring, as an over-stretched O-ring may be more susceptible to washing out or displacement from an increased velocity of fluid flow during a valve closing event. Additionally, the providing of a two-part poppet assembly  200  has the advantage of more cost-efficiently being able to manufacture the half-dovetail surfaces  238 ,  268  as described above and illustrated herein. Yet another advantage of providing the two-part poppet assembly  200  in the flow fuse valve  10  as disclosed herein is to provide a design that minimizes component manufacturing costs while also providing for automated assembly, and more particularly one-direction (sometimes referred to as top-down) assembly. 
     While not being held to any particular theory, it was found that inclusion of the internal flow channels  134  in the design of the flow fuse valve  10  significantly increased the flow rate achievable, which was a significant challenge for achieving the desired operational performance of the flow fuse valve  10 , where in its normal open state the flow fuse valve  10  desirably allows for an unobstructed fluid flow. 
     While an invention has been described herein with reference to example embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the claims. Many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment or embodiments disclosed herein as the best or only mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In the drawings and the description, there have been disclosed example embodiments and, although specific terms and/or dimensions may have been employed, they are unless otherwise stated used in a generic, exemplary and/or descriptive sense only and not for purposes of limitation, the scope of the claims therefore not being so limited. The use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. The use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The term “comprising” as used herein does not exclude the possible inclusion of one or more additional features. And, any background information provided herein is provided to reveal information believed by the applicant to be of possible relevance to the invention disclosed herein. No admission is necessarily intended, nor should be construed, that any of such background information constitutes prior art against an embodiment of the invention disclosed herein.