Patent Publication Number: US-2020282199-A1

Title: Castellated check valves

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to check valves, and more particularly to valve members of check valves having geometries capable of minimizing sticking together of the valve members during bulk packing or during assembly of the check valves. 
     BACKGROUND 
     Patients are commonly injected with IV solutions that are initially provided in an IV reservoir (a bottle or bag) and dripped into the vein of the patient through an IV line. Typically, an injection port is provided along the IV line and adapted to function with a syringe to permit an injectate to be added to the IV solution. A check valve is also commonly included in the IV line to permit fluid flow only in the direction of the patient. This ensures that the injectate flows downstream toward the patient, not upstream toward the IV reservoir. 
     Conventional check valves utilize disc-shaped valve members that are generally flat and usually made of silicone which is naturally sticky. This geometry allows for the valve members to stick together (during bulk packing) thereby causing a condition known as “shingling” which makes automated assembly of the conventional check valves difficult. 
     SUMMARY 
     The present disclosure generally relates to check valves, and more particularly to valve members of check valves having geometries capable of minimizing sticking together of the valve members during bulk packing or during assembly of the check valves. 
     In accordance with various embodiments of the present disclosure, a check valve includes an upper housing, a lower housing, a cavity interposed between and defined by the upper and lower housings, and a valve member mounted in the cavity to selectively permit fluid flow in a first direction, and prevent fluid backflow in a second direction opposite to the first direction. The upper housing defines an inlet of the check valve and the lower housing defines an outlet of the check valve. The cavity fluidly connects the inlet and the outlet. The valve member includes a valve body and a valve stem portion extending axially through a central axis of the valve body. 
     In accordance with various embodiments of the present disclosure, a check valve includes an upper housing defining an inlet of the check valve, a lower housing axially coupled to the upper housing and comprising an outlet of the check valve, and a cavity interposed between and defined by the upper and lower housings for fluidly connecting the inlet and the outlet. The check valve further includes a flexible valve member mounted in the cavity to selectively permit fluid flow in a first direction, and prevent fluid backflow in a second direction opposite to the first direction. The flexible valve member includes a body having a plurality of longitudinally extending feet disposed about an outer circumferential perimeter of the body. 
     In accordance with various embodiments of the present disclosure, a flexible valve member includes a valve body, and a plurality of feet disposed about and extending longitudinally from an outer circumferential perimeter of the valve body. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the subject technology as claimed. It is also to be understood that other aspects may be utilized, and changes may be made without departing from the scope of the subject technology 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following figures are included to illustrate certain aspects of the embodiments, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure. 
         FIG. 1A  is a perspective view of a check valve, in accordance with some embodiments of the present disclosure. 
         FIG. 1B  is a perspective view of a valve member of the check valve of  FIG. 1A , in accordance with some embodiments of the present disclosure. 
         FIG. 1C  illustrates an assembly line of the valve member of the check valve of  FIG. 1B  in accordance with some embodiments. 
         FIG. 2A  is a perspective view of a check valve, in accordance with some embodiments of the present disclosure. 
         FIG. 2B  is a perspective view of a valve member of the check valve of  FIG. 2A , in accordance with some embodiments of the present disclosure. 
         FIG. 2C  illustrates an assembly line of the valve member of the check valve of  FIG. 2B  in accordance with some embodiments. 
         FIG. 3  is a perspective view of a check valve, in accordance with some embodiments of the present disclosure. 
         FIG. 4A  is an exploded perspective view of the check valve of  FIG. 3 , in accordance with some embodiments of the present disclosure. 
         FIG. 4B  is an exploded cross-sectional view of the check valve of  FIG. 3 , in accordance with some embodiments of the present disclosure. 
         FIG. 4C  is an assembly line of the valve member of the check valve of  FIG. 4  in accordance with some embodiments. 
         FIG. 5  is a cross-sectional view of the check valve of  FIG. 3  in the closed state, wherein the check valve restricts fluid flow in the reverse directions, in accordance with some embodiments of the present disclosure. 
         FIG. 6  is an enlarged partial cross-sectional view of the check valve of  FIG. 3  in the closed state, wherein the check valve is subjected to an excessive backpressure, in accordance with some embodiments of the present disclosure. 
         FIG. 7  is a cross-sectional view of the check valve of  FIG. 3  in the open state when subjected to an upstream pressure, where the check valve permits fluid flow in the forward direction, in accordance with some embodiments of the present disclosure. 
         FIG. 8  is an enlarged partial cross-sectional view of the check valve of  FIG. 3  in the open state when subjected to an upstream pressure, where the check valve permits fluid flow in the forward direction, in accordance with some embodiments of the present disclosure. 
         FIG. 9A  is a perspective view of a check valve, in accordance with some embodiments of the present disclosure. 
         FIG. 9B  is a perspective view of a valve member of the check valve of  FIG. 9A , in accordance with some embodiments of the present disclosure. 
         FIG. 10A  is a cross-sectional view of the check valve of  FIG. 9A  in the closed state, wherein a central axis of the valve member of  FIG. 9B  is misaligned with a central axis of the check valve, in accordance with some embodiments of the present disclosure. 
         FIG. 10B  is a cross-sectional view of the valve member of  FIG. 9B  misaligned with the central axis of the check valve, in accordance with some embodiments of the present disclosure. 
         FIG. 10C  is a cross-sectional view of the check valve of  FIG. 9A  in the open state, wherein the central axis of the valve member of  FIG. 9B  is misaligned with the central axis of the check valve, in accordance with some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below describes various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the subject technology. Accordingly, dimensions may be provided in regard to certain aspects as non-limiting examples. However, it will be apparent to those skilled in the art that the subject technology may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject technology. 
     It is to be understood that the present disclosure includes examples of the subject technology and does not limit the scope of the appended claims. Various aspects of the subject technology will now be disclosed according to particular but non-limiting examples. Various embodiments described in the present disclosure may be carried out in different ways and variations, and in accordance with a desired application or implementation. 
     The present description relates in general to check valves, and more particularly, for example and without limitation, to more particularly to valve members of check valves having geometries capable of minimizing sticking together of the valve members during bulk packing or during assembly of the check valves. 
     In accordance with some embodiments, the valve member may include a valve body and a valve stem portion extending axially through a central axis of the valve body. The valve members of the various embodiments described herein are advantageous in that the valve body and the valve stem portion may define a “jack” shape geometry that will reduce the exposed surface area available for sticking of the valve members during assembly. In particular, the presence of the valve stem portion limits the exposed surface area of the valve bodies available for sticking or “shingling.” In some embodiments, the exposed surface area of the valve members available for sticking is reduced by up to 69%. The valve members can then be fed along an assembly line or track with reduced surface area for sticking and/or friction. 
     In accordance with some embodiments, the valve member either including or excluding the stem portion may additionally include plurality of feet at an outer circumferential perimeter of the valve body. The feet may each extend longitudinally from the outer circumferential perimeter of the valve body. The feet may be spaced apart from each other so as to form a castle-like shape around the perimeter of the valve body, and thus may be referred to as castellated feet. As depicted, the castellated feet may be oriented substantially perpendicularly with respect to the outer circumferential perimeter of the valve body. Benefits are realized in the geometry of the valve members with the castellated feet in that the castellated feet further prevent or obstruct contacting of the upper and/or lower surfaces of the valve bodies during bulk packing, assembly and/or transportation. In particular, since the upper surface of each of the castellated feet protrudes and is thus raised above the upper surface of the valve body, contacting and sticking together of the exposed surface areas of the upper surfaces of the valve body is limited. Similarly, since the lower surface of each of the castellated feet protrudes below the lower surface of the valve body, contacting and sticking together of the exposed surface areas of the lower surfaces of the valve body is limited. Additional benefits are realized in that due to the longitudinally protruding structure of the castellated feet, the valve member is capable of being maintained concentrically in a cavity of the check valve when the valve experiences a back pressure condition. Valves are symmetrical and can be assembled on either side. 
       FIG. 1A  is a perspective view of a check valve  100 , in accordance with some embodiments of the present disclosure.  FIG. 1B  is a perspective view of a valve member  35  of the check valve of  FIG. 1A , in accordance with some embodiments of the present disclosure.  FIG. 1C  illustrates an assembly line of the valve member  35  of the check valve  100  of  FIG. 1B  in accordance with some embodiments. As depicted, a top portion of the check valve  100  (i.e., an upper housing  10 ) is displayed in cross-sectional view to more clearly illustrate some of the features of the check valve  100 . Referring to  FIG. 1 , the check valve  100  includes an axially extending body  101  defining a central longitudinal axis X 1 . The body  101  may be a generally cylindrical (or tubular) structure and may include an upper housing  10  and a lower housing  15 . The upper housing  10  may include a first end portion  12  and an axially opposite second end portion  14 . As illustrated, a radial extent of the upper housing  10  at the second end portion  14  may be greater than the radial extent thereof at the first end portion  12 . The lower housing  15  may include an upstream internal surface  52 , and the second end portion  14  and the upstream internal surface  52  of the lower housing  15  may axially contact each other to co-operatively form a cavity  30  of the check valve  100 . 
     The upper housing  10  may include an inlet  20  of the check valve  100  at the first end  12 , and the lower housing  15  may include an outlet  25  of the check valve  100 . The body  101  may define an internal flow passage  85  axially extending between the inlet  20  and the outlet  25  and in fluid communication therewith. As is understood, the check valve  100  may permit fluid to flow from the inlet  20  to the outlet  25  (as indicated by arrow A), and minimize, or otherwise limit, fluid flow from the outlet  25  to the inlet  20  (as indicated by arrow B). As depicted, the upper housing  10  and the lower housing  15  may define the cavity  30  for fluidly connecting the inlet  20  and the outlet  25 . In the depicted embodiments the flexible valve member  35  may be mounted in the cavity  30  to selectively permit fluid flow in the first direction (indicated by arrow A), and prevent fluid backflow (reverse flow) in the second direction opposite to the first direction (indicated by arrow B). 
     In accordance with some embodiments, the valve member  35  may have a valve body  22  and a valve stem portion  18  extending axially through a central axis X 2  of the valve body  22 . The valve body  22  may be in the form of a disc or any other circular plate. As depicted, the valve member  35  may be mounted on a support portion  28  of the lower housing  14 . In particular, the support portion  28  may include a central aperture  44  and a plurality of axially extending slots  46  through which fluid flowing from the inlet  20  and into the cavity  30  may enter the outlet  25  in an open state of the check valve  100 . As depicted, the valve stem portion  18  of the valve member  35  may be mounted in the central aperture  44  of the support portion. The aforementioned configuration of the valve member  35  may provide several manufacturing and assembly advantages. A common issue experienced during packaging, transportation and assembly of the check valve is that when conventional valve members (e.g., disc-type check valve members) are packaged in bulk and/or transported on a conveyance line, the valve members are prone to shingling. In particular, since conventional disc-type valve members are generally flat and made of silicone which is naturally sticky, this geometry allows for the conventional disc-type valve members to stick together (during bulk packing), thereby causing the “shingling”. This makes automated assembly difficult. The valve member  35  of the various embodiments described herein is advantageous in that the valve body  22  and the valve stem portion  18  may define a “jack” shape geometry of the valve member  35  that will reduce the exposed surface area available for sticking of the valve members  35  during assembly. In particular, the presence of stem portion  18  limits the exposed surface area of the bodies  22  available for sticking or shingling. The probability for sticking of the valve members to occur is thus much lower since the stem portions will keep surfaces of the bodies apart at least in part. In some embodiments, the exposed surface area of the valve members  35  available for sticking is reduced by up to 69%. As illustrated in  FIG. 1C , the valve members  35  can now be fed along a track  70 A with reduced surface area for sticking and/or friction. Additional benefits are realized in that since the valve members  35  will be concentrically disposed in the cavity  30  of the check valve  100 , peripheral circumferential edges of the valve member  35  are prevented from contacting an internal surface, e.g., a downstream internal surface  59  (described in further detail below) of the upper housing  10 , which could hold the valve open. Furthermore, because the valve member  35  is symmetrically shaped it can be assembled on either side thereof. 
     Referring back to  FIG. 1A , the support portion  28  may be centrally disposed in the cavity  30 , and a central axis X 3  of the support portion  28  may be coaxially aligned with the central longitudinal axis X 1  of the body  101 . The support portion  28  may be coupled to, integrally formed with, or otherwise protrude from the upstream internal surface  52  of the lower housing  15 , and extend into the cavity  30 . As discussed in further detail below, the cavity  30  may form a part of the internal flow passage  85 , or may be otherwise fluidly communicated with the internal flow passage  85  and therefore, fluid flowing from the inlet  20  to the outlet  25  may flow via the cavity  30 . 
       FIG. 2A  is a perspective view of a check valve  200 , in accordance with some embodiments of the present disclosure.  FIG. 2B  is a perspective view of a valve member  37  of the check valve  200  of  FIG. 2A , in accordance with some embodiments of the present disclosure.  FIG. 2C  illustrates an assembly line of the valve member  37  of the check valve  200  of  FIG. 2B  in accordance with some embodiments. As depicted, a top portion of the check valve  200  (i.e., an upper housing  11 ) is displayed in cross-sectional view to more clearly illustrate some of the features of the check valve  200 . Referring to  FIG. 2A , similar to the embodiments of  FIG. 1A , the check valve  200  includes an axially extending body  201  defining a central longitudinal axis X 1 . The body  201  may be a generally cylindrical (or tubular) structure and may include an upper housing  11  and a lower housing  16 . The upper housing  11  may include a first end portion  19  and an axially opposite second end portion  21 . As illustrated, a radial extent of the upper housing  11  at the second end portion  21  may be greater than the radial extent thereof at the first end portion  19 . The lower housing  16  may include an upstream internal surface  52 , and the second end portion  21  and the upstream internal surface  52  of the lower housing  16  may axially contact each other to co-operatively form a cavity  30  of the check valve  200 . 
     The upper housing  11  may include an inlet  20  of the check valve  200  at the first end  19 , and the lower housing  16  may include an outlet  25  of the check valve  200 . Similar to the embodiments of  FIG. 1A , the body  201  may define an internal flow passage  85  axially extending between the inlet  20  and the outlet  25  and in fluid communication therewith. As is understood, the check valve  200  may permit fluid to flow from the inlet  20  to the outlet  25 , and minimize or otherwise limit, fluid flow from the outlet  25  to the inlet  20 . As depicted, the upper housing  11  and the lower housing  16  may define the cavity  30  for fluidly connecting the inlet  20  and the outlet  25 . In the depicted embodiments the flexible valve member  37  may be mounted in the cavity  30  to selectively permit fluid flow from the inlet  20  to the outlet  25 , and prevent fluid backflow (reverse flow) from the outlet  25  to the inlet  20 . 
     In accordance with some embodiments, similar to the valve member  35 , the valve member  37  may have a valve body  22  and a valve stem portion  18  extending axially through the central axis X 2  of the valve body  22 . In the depicted embodiments, the valve member  37  additionally has a plurality of feet  24  disposed along an outer circumferential perimeter  33  of the valve body  22 . The feet  24  may each extend longitudinally from the outer circumferential perimeter  23  of the valve body  22 . As depicted, the feet  24  may be oriented substantially perpendicularly with respect to the outer circumferential perimeter  23  of the valve body  22 . In particular, the feet  24  may extend from and protrude substantially perpendicularly from an upper surface  22 A and a lower surface  22 B of the valve body  22 . As such, an upper surface  24 A of each of the feet  24  may be positioned or protrude a predetermined height above the upper surface  22 A of the valve body  22 . Similarly, a lower surface  24 B of each of the feet  24  may be positioned or protrude a predetermined height below the lower surface  22 B of the valve body  22 . In some embodiments, the feet  24  may be spaced apart from each other at regular intervals. For example, the valve member  37  may have two or more feet  24  equally spaced apart from each other. In other embodiments. However, the feet  24  may be spaced apart from each other at irregular intervals. For example, a spacing between each of the feet may vary according to the desired application. In some embodiments, adjacent pairs of the feet  24  define a recessed flow portion  29  therebetween, and through which fluid entering the cavity  30  from the upper housing may flow into the lower housing. 
     As depicted, the feet  24  may have a polygonal shape, for example a rectangular, square or any other suitable polygonal shape. In other embodiments, the feet  24  may have a curved shape, for example a circular, an oval or oblong shape. The configuration of the valve member  37  with adjacent feet  24  interposed by respective recessed flow portions  29  may yield a structure resembling that of a castle. Thus, the feet  24  may be referred to herein as castellated feet  24 . However, the various embodiments of the present disclosure are not limited the aforementioned configurations, and the shapes and spacing apart (i.e. the extent or size of the recessed flow portions  29 ) of the feet  24  from each other may be varied as desired. 
     Similar to the embodiments of  FIG. 1A , the valve member  37  may be mounted on a support portion  28  of the lower housing  16 . In particular, the support portion  28  may include a central aperture  44  and a plurality of axially extending slots  46  through which fluid flowing from the inlet  20  and into the cavity  30  may enter the outlet  25  in an open state of the check valve  200 . As depicted, the valve stem portion  18  of the valve member  35  may be mounted in the central aperture  44  of the support portion  28 . The aforementioned configuration of the valve member  37  may provide similar and additional manufacturing and assembly advantages as the valve member  35  of  FIGS. 1A -IC. In particular, due to the valve member  37  also being configured with the valve stem portion  18 , the common issues described above which are experienced during packaging, assembly, and transportation are minimized. The “jack” shape geometry of the valve member  37  reduces the exposed surface area available for sticking of the valve members  35  during assembly, thereby reducing the possibility of occurrence of “shingling” or sticking together of the surfaces of the valve bodies  22  during transportation or assembly. 
     In some embodiments, the exposed surface area of the valve members  37  available for sticking is reduced by up to 69%. As illustrated in  FIG. 2C , the valve members  37  can now be fed along a track  70 B with reduced surface area for sticking and/or friction. Benefits are realized in the geometry of the valve members  37  in that the castellated feet  24  further prevent or obstruct contacting of the upper and/or lower surfaces  22 A,  22 B of the valve bodies  22  during assembly and/or transportation. In particular, the configuration of the valve members  37  in which the upper surface  24 A of each of the castellated feet  24  protrudes and is thus raised above the upper surface  22 A of the valve body  22  further limits the exposed surface area of the lower surfaces  22 A from contacting and sticking to each other. Similarly, the configuration of the valve members  37  in which the lower surface  24 B of each of the castellated feet  24  protrudes below the lower surface  22 B of the valve body  22  further limits the exposed surface area of the lower surfaces  22 B from contacting and sticking to each other. Thus, the probability for sticking of the valve members  37  to occur is much lower than conventional valve members as the castellated feet  24  will keep surfaces of the bodies  22  apart at least in part. In some embodiments, the exposed surface area of the valve members  37  available for sticking is reduced by up to 69%. As can be appreciated, the degree of reduction of the exposed surface area of the valve members  37  that is available for sticking may vary accordingly based on the size and geometry of the castellated feet  24 . Additional benefits are realized in that due to the longitudinally protruding structure of the castellated feet  24 , the valve member  37  is capable of being maintained concentrically in the cavity  30  of the check valve  200  when the valve member  37  experiences a back pressure condition. Furthermore, because the valve member  37  is symmetrically shaped it can be assembled on either side thereof. In all other respects, the valve member  37  may be identical to the valve member  35  described above with respect to  FIG. 1B . 
     In accordance with some embodiments, the check valve  200  may further include a filter member  26  coupled, attached or otherwise bonded to an internal surface, e.g., surface  55  of the upper housing  11 . For example, the filter member  26  may be coupled, attached or otherwise bonded to a ledge  53  of the internal surface  55  through any appropriate methods including, but not limited to ultrasonic welding, heat sealing, insert molding, gluing or other attachment methods. The filter member  26  may be disposed upstream of, and spaced apart from the valve member  37 . As such, when the valve member  37  is subjected to an excessive reverse flow (flow from the outlet  25  to the inlet  20 ) causing the valve member  37  to bow or deflect upwards, a gap remains between the filter member  26  and the valve member  37  to prevent the valve member  37  from stretching the filter member  26  past its elastic limit. Thus integrity of the filter member  26  is maintained even in the excessive backflow condition. The filter member  26  may be configured to restrict and minimize passage of undesirable matter in the fluid flowing through the check valve  200 . 
     The filter member  26  may be formed of a porous material capable of preventing particulate matter of a particular size from passing through and potentially reaching and causing failure of the valve member  37 . For example, the filter member  26  may be formed of a porous plastic material. Alternatively, the filter member  26  may be made of a non-woven cast material, a cork material, or any other porous fabric or material. The filter member  26  may be formed with a plurality of small holes or it may be woven, to provide pores of about 20 to 200 microns in size. In some embodiments, filter member  26  may be a flexible material such as a metal or polymeric material. In some embodiments, the filter member  40  may be formed of a material capable of withstanding or filtering flow rates of between 3 to 8 liters per hour. Additionally, the filter member  26  may be formed of a porous material capable of withstanding backpressures resulting from reverse flow of up to 200 KPa. Advantageously, the latter configuration may minimize the possibility of the filter member  26  collapsing under the backpressure resulting from reverse fluid flow. 
       FIG. 3  is a perspective view of a check valve  300 , in accordance with some embodiments of the present disclosure.  FIG. 4A  is an exploded perspective view of the check valve  300  of  FIG. 3 , in accordance with some embodiments of the present disclosure.  FIG. 4B  is an exploded cross-sectional view of the check  300  valve of  FIG. 3 , in accordance with some embodiments of the present disclosure.  FIG. 4C  illustrates an assembly line of the valve member  39  of the check valve of  FIG. 4  in accordance with some embodiments. 
     Referring to  FIG. 3 , a top portion of the check valve  300  (i.e., an upper housing  13 ) is displayed in cross-sectional view to more clearly illustrate some of the features of the check valve  300 . Referring to  FIGS. 3-4B , similar to the embodiments of  FIGS. 1A and 2A , the check valve  300  includes an axially extending body  301  defining a central longitudinal axis X 1 . The body  301  may be a generally cylindrical (or tubular) structure and may include an upper housing  13  and a lower housing  17 . The upper housing  13  may include a first end portion  29  and an axially opposite second end portion  31 . As illustrated, a radial extent of the upper housing  11  at the second end portion  31  may be greater than the radial extent thereof at the first end portion  29 . The lower housing  17  may include an upstream internal surface  52 , and the second end portion  31  and the upstream internal surface  52  of the lower housing  17  may axially contact each other to co-operatively form a cavity  30  of the check valve  300 . 
     The upper housing  13  may include an inlet  20  of the check valve  300  at the first end  19 , and the lower housing  17  may include an outlet  25  of the check valve  300 . Similar to the embodiments of  FIG. 1A , the body  201  may define an internal flow passage  85  axially extending between the inlet  20  and the outlet  25  and in fluid communication therewith. As is understood, the check valve  300  may permit fluid to flow from the inlet  20  to the outlet  25 , and minimize or otherwise limit, fluid flow from the outlet  25  to the inlet  20 . As depicted, the upper housing  13  and the lower housing  17  may define the cavity  30  for fluidly connecting the inlet  20  and the outlet  25 . In the depicted embodiments the flexible valve member  39  may be mounted in the cavity  30  to selectively permit fluid flow from the inlet  20  to the outlet  25 , and prevent fluid backflow (reverse flow) from the outlet  25  to the inlet  20 . 
     In accordance with some embodiments, the valve member  39  may be similar in structure to the valve member  37 , with the exception that the valve member  39  excludes the valve stem portion  18 . Thus, similar to the valve member  37 , the valve member  39  may have a plurality of longitudinally extending feet  24  at an outer circumferential perimeter  23  of the valve body  22 . As described above, the feet  24  may be disposed around the outer circumferential perimeter  23  of the valve body  22  in manner resembling that of a castle, and therefore may be referred to herein as castellated feet  42 . The castellated feet  24  may each extend longitudinally from the outer circumferential perimeter  23  of the valve body  22 . Since the castellated feet  24  of the valve member  37  are identical to the castellated feet  24  of the valve member  39  and a detailed description of the castellated feet  24  was provided with respect to the valve member  37 , a detailed description thereof shall be omitted with respect to the valve member  39 . 
     In the depicted embodiments, the valve member  39  may be mounted on a support portion  34  of the lower housing  17 . The configuration of the valve member  39  with the plurality of castellated teeth  24  may provide similar manufacturing and assembly advantages as the valve member  37  of  FIGS. 2A-2C . In particular, benefits are realized in the geometry of the valve members  39  in that the castellated feet  24  prevent or obstruct contacting of the upper and/or lower surfaces  22 A,  22 B of the valve bodies  22  during bulk packaging, assembly and/or transportation. For example, as illustrated in  FIG. 4C , the valve members  39  can now be fed along a track  70 C with reduced surface area for sticking and/or friction. In particular, as described above with respect to the valve member  37 , the configuration of the valve members  39  in which the upper surface  24 A of each of the castellated feet  24  protrudes and is thus raised above the upper surface  22 A of the valve body  22  further limits the exposed surface area of the lower surfaces  22 A from contacting and sticking to each other. Similarly, the configuration of the valve members  39  in which the lower surface  24 B of each of the castellated feet  24  protrudes below the lower surface  22 B of the valve body  22  further limits the exposed surface area of the lower surfaces  22 B from contacting and sticking to each other. Thus, the probability for sticking of the valve members  39  to occur is much lower than conventional valve members as the castellated feet will keep surfaces of the bodies  22  apart at least in part. In some embodiments, the exposed surface area of the valve members  39  available for sticking is reduced by up to 69%. As can be appreciated, the degree of reduction of the exposed surface area of the valve members  39  that is available for sticking may vary accordingly based on the size and geometry of the castellated feet  24 . 
     Additional benefits are realized in that due to the longitudinally protruding structure of the castellated feet  24 , the valve member  39  is capable of being maintained concentrically in the cavity  30  of the check valve  300  when the valve member  39  experiences a back pressure condition. Furthermore, because the valve member  39  is symmetrically shaped it can be assembled on either side thereof. In all other respects, the valve member  39  may be identical to the valve member  37  described above with respect to  FIG. 2B . 
     In accordance with some embodiments, the check valve  300  may further include a filter member  26  coupled, attached or otherwise bonded to an inner surface, e.g., surface  59  of the upper housing  13 . For example, the filter member  26  may be coupled, attached or otherwise bonded through any appropriate methods including, but not limited to ultrasonic welding, heat sealing, insert molding, gluing or other attachment methods. The filter member  26  may be disposed upstream of, and spaced apart from the valve member  37 . As depicted, the filter member  26  may be coupled or otherwise attached to a ledge  53  of an internal surface  55  of the upper housing  13 . The filter member  26  may be configured to restrict and minimize passage of undesirable matter in the fluid flowing through the check valve  300 . 
     The filter member  26  may be formed of a porous material capable of preventing particulate matter of a particular size from passing through and potentially reaching and causing failure of the valve member  37 . For example, the filter member  26  may be formed of a porous plastic material. Alternatively, the filter member  26  may be made of a non-woven cast material, a cork material, or any other porous fabric or material. The filter member  26  may be formed with a plurality of small holes or it may be woven, to provide pores of about 20 to 200 microns in size. In some embodiments, filter member  26  may be a flexible material such as a metal or polymeric material. In some embodiments, the filter member  40  may be formed of a material capable of withstanding or filtering flow rates of between 3 to 8 liters per hour. Additionally, the filter member  26  may be formed of a porous material capable of withstanding backpressures resulting from reverse flow of up to 200 KPa. Advantageously, the latter configuration may minimize the possibility of the filter member  26  collapsing under the backpressure resulting from reverse fluid flow. 
     In accordance with some embodiments, the upper housing  13  may include at least one longitudinally extending rib  45  that protrudes radially inward from the upstream internal surface  57 . The at least one longitudinally extending rib  45  may be configured as a protruding surface which is disposed directly above or upstream of the filter member  26 . In some embodiments, the filter member  26  may be disposed between the plurality of longitudinally extending ribs  45  and the flexible valve member  39 . As depicted, the filter member  26  is positioned spaced apart from and disposed with a gap G between the filter member  26  and distal ends  51  of the plurality of ribs  45 . The aforementioned configuration is advantageous to maximize surface area for fluid flow from the inlet into the cavity and to minimize obstruction of fluid flow from the inlet  20  to the outlet  25 . 
       FIGS. 5-8  are cross-sectional views of check valve  300 , in accordance with some embodiments of the present disclosure.  FIG. 5  is a cross-sectional view of the check valve of  FIG. 3  in the closed state, wherein the check valve restricts fluid flow in the reverse directions, in accordance with some embodiments of the present disclosure. As depicted, the upper housing  13  may include the internal surface  55  extending along the length of the interior of the upper housing  13  and defining the flow passage  85 . The internal surface  55  may include the upstream internal surface  57  and the downstream internal surface  59 . The cavity  30  may be at least partially defined by the downstream internal surface  59  of the upper housing  13 . In the depicted embodiments, the downstream internal surface  59  extends radially outward from the upstream internal surface  57 . The downstream internal surface  59  may include a projection  40  which extends circularly about the central longitudinal axis X 1  of the body  301  and into the cavity  30 . In some embodiments, the projection  40  defines a sealing surface  42  at a distal end thereof. The projection  40  and therefore the sealing surface  42  may be disposed like a ring above the valve member  39 . As illustrated in  FIGS. 5 and 6 , in the normally-closed state of the check valve  300 , the valve member  39  contacts the sealing surface  42 . Because the valve member  39  contacts the sealing surface  42 , reverse flow (backflow) of fluid from the outlet  25  to the inlet  20  is prevented. 
     During operation, when a downstream pressure (i.e., a pressure applied by a fluid flowing from the outlet  25  to the inlet  20  is applied to the valve member  39 , the valve member  39  may deflect towards the sealing surface  42  to block the fluid communication between the inlet  20  and the cavity  30 , thereby restricting backflow of the fluid from the outlet  25  to the inlet  20 . Preventing backflow of the fluid is advantageous in that it restricts undesirable particulate matter, for example, contained in a drug dispensed from a secondary path from flowing back through the check valve  300 , thereby preventing the patient from receiving the proper drug dosage concentration or from timely delivery of the drug. 
       FIG. 6  is an enlarged partial cross-sectional view of the check valve of  FIG. 3  in the closed state, wherein the check valve is subjected to an excessive backpressure, in accordance with some embodiments of the present disclosure. For example, an excessive back pressure exerted on the valve member  39  may cause the valve member to deflect or bend to such an extent that it abuts the filter member  26 , and exerts an upward force on the filter member  26 . When the valve member  39  is subjected to an excessive backpressure as illustrated in  FIG. 6 , the plurality of longitudinally extending ribs  45  are advantageously configured to support the valve member  39  and limit the extent to which the valve member  39  stretches the filter member  26  when the valve member  39  is subjected to excessive back pressure. To this effect, the plurality of longitudinally extending ribs  45  prevent the valve member  39  from bowing to an extent where the valve member  39  overstretches and plastically deforms or otherwise damages the filter member  26 . The plurality of longitudinally extending ribs  45  thus act as a support member for the valve member  39  in the case of an excessive backflow so that it is not necessary for the filter member  26  to support the valve member  39  during excessive backflow. Thus, the plurality of longitudinally extending ribs also function advantageously to prevent the filter member  39  from being displaced upwards into the inlet  20  when excessive back pressures are experienced in the check valve  300 . Due to the presence of the longitudinally extending ribs  45 , the filter member  26  is prevented from being displaced upwards and into the inlet  20  as a result of the force exerted by the deflected valve member  39 . 
       FIG. 7  is a cross-sectional view of the check valve  300  of  FIG. 3  in the open state when subjected to an upstream pressure, where the check valve  300  permits fluid flow in the forward direction, in accordance with some embodiments of the present disclosure.  FIG. 8  is an enlarged partial cross-sectional view of the check valve  300  of  FIG. 3  in the open state when subjected to an upstream pressure, where the check valve  300  permits fluid flow in the forward direction, in accordance with some embodiments of the present disclosure. 
     As depicted, during operation, fluid may enter the check valve  300  via the inlet  20 , and flow through the filter member  26  where it is filtered to trap the undesirable particulate matter, and into the cavity  30 . Any grit or other undesirable particulate matter larger in size than the pores of the filter member  26  may be trapped in the filter member  40 , and prevented from passing downstream to the valve member  39 . The upstream pressure (i.e., pressure applied by fluid flowing from the inlet  20  to the outlet  25 ) applied to the valve member  39  causes the valve member  39  to bow or bend downwards at the outer edges thereof and deflect away from the sealing surface  42 . Thus, the check valve is shifted from the closed state to an open state where the inlet  20 , the cavity  30 , and the outlet  25  are fluidly communicated. In the open state, a gap may be created between the sealing surface  42  and the upper surface  22 A of the valve member  35  to allow the filtered fluid to flow therethrough. The filtered fluid may then flow through the gap, into the cavity  30 , and exit the check valve  100  via the outlet  25  in the lower housing  17 . 
     The configuration in which the filter member  40  is positioned upstream of the valve member is advantageous in that it prevents passage of undesirable particulate matter to the valve member  35  which could otherwise cause damage or wear to the valve member. The aforementioned configuration also prevents the undesirable particulate matter from potentially becoming lodged between the valve member  40  and the sealing surface  70 , thereby preventing the valve member  35  from fully closing and sealing against reverse flow (backflow). 
     In contrast, in a conventional check valve configuration which does not include an integrated filter member, during low flow conditions, pressure exerted on the check valve as a result of the fluid flow may not be sufficient to fully open the check valve (e.g., to deflect the valve member  35 ) such that grit (or other undesirable particulate matter) may pass through the gap. In such conditions, the grit may get lodged in the gap and the valve may not completely close. This undesirably causes the check valve to “weep,” and allow fluid to flow through the valve in the reverse direction, thereby making the check valve ineffective. 
       FIG. 9A  is a perspective view of a check valve  400 , in accordance with some embodiments of the present disclosure. As depicted, a top portion of the check valve  400  (i.e., an upper housing  13 ) is displayed in cross-sectional view to more clearly illustrate some of the features of the check valve  400 . Similar to the check valve  300  of  FIGS. 3 and 5 , the check valve  400  includes an axially extending body  401  defining a central longitudinal axis X 1 . The body  401  may be a generally cylindrical (or tubular) structure and may include an upper housing  13  and a lower housing  17 . In accordance with some embodiments, the upper and lower housings  13  and  17  are similar in structure to the upper and lower housings  13  and  17  of the check valve  300 , thus a detailed description thereof shall be omitted with respect to the check valve  400 . 
     In accordance with some embodiments, the valve member  41  may be similar in structure to the valve member  39 , with the exception that the valve member  41  includes an additional friction rib  43  not present in valve member  39 . Thus, similar to the valve member  39 , the valve member  41  may have a plurality of longitudinally extending feet  24  at an outer circumferential perimeter  23  of the valve body  22 . As described above, the feet  24  may be disposed around the outer circumferential perimeter  23  of the valve body  22  in manner resembling that of a castle, and therefore may be referred to herein as castellated feet  24 . The castellated feet  24  may each extend longitudinally from the outer circumferential perimeter  23  of the valve body  22 . Since a detailed description of the castellated feet  24  was provided with respect to the valve member  37 , a detailed description thereof shall be omitted with respect to the valve member  41 . 
     In the depicted embodiments, the valve member  41  may be mounted on a support portion  34  of the lower housing  17 . The configuration of the valve member  41  with the plurality of castellated feet  24  may provide similar manufacturing and assembly advantages as the valve member  39  of  FIGS. 3-8 . In particular, as previously discussed with respect to valve members  37  and  39 , benefits are realized in the geometry of the valve members  41  in that the castellated feet  24  prevent or obstruct contacting of the upper and/or lower surfaces  22 A,  22 B of the valve bodies  22  during assembly and/or transportation. In particular, as described above with respect to the valve members  37  and  39 , the configuration of the valve members  41  in which the upper surface  24 A of each of the castellated feet  24  protrudes and is thus raised above the upper surface  22 A of the valve body  22  further limits the exposed surface area of the lower surfaces  22 A from contacting and sticking to each other. Similarly, the configuration of the valve members  41  in which the lower surface  24 B of each of the castellated feet  24  protrudes below the lower surface  22 B of the valve body  22  further limits the exposed surface area of the lower surfaces  22 B from contacting and sticking to each other. Thus, the probability for sticking of the valve members  41  to occur is much lower than conventional valve members as the castellated feet  24  will keep surfaces of the bodies  22  apart at least in part. In some embodiments, the exposed surface area of the valve members  41  available for sticking is reduced by up to 69%. As can be appreciated, the degree of reduction of the exposed surface area of the valve members  41  that is available for sticking may vary accordingly based on the size and geometry of the castellated feet  24 . 
     Additional benefits are realized in that due to the longitudinally protruding structure of the castellated feet  24 , the valve member  41  is capable of being maintained concentrically in the cavity  30  of the check valve  400  when the valve member  41  experiences a back pressure condition. Furthermore, because the valve member  41  is symmetrically shaped it can be assembled on either side thereof. In all other respects, the valve member  41  may be identical to the valve member  39  described above with respect to  FIGS. 3-8 . 
     In accordance with some embodiments, the valve members  35 ,  37 ,  39 , and  41  may be formed of a flexible, resilient material which is fluid impervious. For example, the valve members  35 ,  37 ,  39 , and  41  may be made of a silicon material. In other embodiments, however, the valve members  35 ,  37 ,  39 , and  41  may be formed of any non-sticking, resilient material such as natural or synthetic rubber or plastic. The valve members  35 ,  37 ,  39 , and  41  may be formed of a material having a shore hardness of 70 or less. 
     In some embodiments, the valve members  35 ,  37 ,  39 , and  41  are not limited to any particular shape or size. In the depicted embodiments, however, the size of the valve members  35 ,  37 ,  39 , and  41  may be limited based on desired deflection/bending characteristics of the valve members valve members  35 ,  37 ,  39 , and  41  when subjected to either of the upstream or downstream forces. For example, the valve members  35 ,  37 ,  39 , and  41  may be sized and shaped so as to flex or bend under fluid pressure to permit forward flow (from the inlet  20  to the outlet  25 ) of the fluid into the cavity  30 , and to limit fluid flow in the reverse direction. 
     In accordance with some embodiments, the check valve  400  may further include a filter member  26  coupled, attached or otherwise bonded to an inner surface, e.g., surface  59  of the upper housing  13 . Since a detailed description of the filter member  26 , how it functions, and how it may be coupled, attached or otherwise bonded to the upper housing  13  was provided with respect to the valve members  37 , a detailed description thereof shall be omitted with respect to the valve member  41 . 
       FIG. 9B  is a perspective view of a valve member  41  of the check valve  400  of  FIG. 9A , in accordance with some embodiments of the present disclosure. As depicted, at least one of the castellated feet  24  of the valve member  41  includes a curved friction rib  43  extending radially outward from an outer surface of the castellated foot  24 . The curved shape of the friction rib  43  may be advantageous over other rib shapes, for example a rib having a flatter or straighter shape because the curved shape or profile allows for reduced friction of the curved rib  43  with the downstream internal surface  59  as compared to a flat-shaped rib. The friction rib  43  may have a structure and/or be made of a may be formed of a flexible, resilient material which is capable of dampening or otherwise reducing a force, e.g., a friction force between the friction rib  43  and the downstream internal surface  59  of the upper housing  13 . For example, the friction rib  43  may be made of a silicon material. In other embodiments, however, the friction rib  43  may be formed of any non-sticking, resilient material such as natural or synthetic rubber or plastic. The aforementioned configuration of the valve member  41  with the friction ribs  43  is advantageous in that in the event that the valve member  41  becomes offset from its mounting position in the cavity  30  to the point where it contacts the downstream internal surface  59 , only the friction ribs  43  which protrude radially outward a greater extent than the castellated feet would contact downstream internal surface  59 . Thus, a surface area of the valve member  41  which contacts the downstream internal surface  59  is drastically reduced. Accordingly, a reduced surface area of the valve member  41  contacting the downstream internal surface  59  leads to reduced friction forces between the valve member and the upper housing as compared to a conventional valve member without the outward protruding friction ribs  43 . 
       FIG. 10A  is a cross-sectional view of the check valve  400  of  FIG. 9A  in a closed state, wherein a central axis X 4  of the valve member  41  of  FIG. 9B  is misaligned with a central axis X 1  of the check valve  400 , in accordance with some embodiments of the present disclosure.  FIG. 10B  is a cross-sectional view of the valve member  41  of  FIG. 9B  misaligned with the central axis of the check valve  400 , in accordance with some embodiments of the present disclosure.  FIG. O1C  is a cross-sectional view of the check valve  400  of  FIG. 9A  in an open state, wherein the central axis X 4  of the valve member  41  of  FIG. 9B  is misaligned with the central axis X 1  of the check valve  400 , in accordance with some embodiments of the present disclosure. 
     As illustrated in  FIG. 10A , in the normally-closed state of the check valve  400 , the valve member  39  contacts the sealing surface  42 . Because the valve member  41  contacts the sealing surface  42 , reverse flow (backflow) of fluid from the outlet  25  to the inlet  20  is prevented. During operation, when a downstream pressure (i.e., a pressure applied by a fluid flowing from the outlet  25  to the inlet  20 ) is applied to the valve member  41 , the valve member  41  may deflect towards the sealing surface  42  to block the fluid communication between the inlet  20  and the cavity  30 , thereby restricting backflow of the fluid from the outlet  25  to the inlet  20 . 
     In some embodiments, the downstream pressure applied by the fluid flowing from the outlet  25  to the inlet  20  which places check valve  400  in the closed state may cause the valve member  41  to be displaced from its mounting position on the support portion  34 . In particular, a central axis X 4  of the valve member  41  may be misaligned with the central longitudinal axis X 1  of the check valve such that the valve member  41  contacts the downstream internal surface  59  of the upper housing  13 . The aforementioned configuration of the valve member  41  with the castellated feet  24  having the curved friction ribs  43  is advantageous in that since the friction ribs  43  protrude radially outward a greater extent than an outer surface of the castellated feet  24 , only the portion of the valve member  41  on which the friction ribs  43  are disposed contacts the downstream internal surface  59 . Thus, as illustrated in  FIG. 10B , a surface area of the valve member  41  which contacts the downstream internal surface  59  is drastically reduced as compared to a conventional valve member configuration without the friction ribs  43 . The reduced surface area of the valve member  41  contacting the downstream internal surface  59  leads to reduced friction forces between the valve member  41  and the internal surface of the upper housing as compared to a conventional valve member which does not have the outward protruding friction ribs  43 . For example, in some embodiments, as illustrated in  FIG. 10B , the surface area of the valve member  41  which contacts the downstream internal surface  59  is based on the number of friction ribs capable of contacting the downstream internal surface  59  at a time. As depicted, since a maximum of two of the friction ribs  43  contact the downstream internal surface  59  at a time, the surface area of the valve member  41  which contacts the downstream internal surface  59  is limited to the surface area of the maximum two friction ribs  43  which actually contact the downstream internal surface  59  at a given time. 
     As illustrated in  FIG. 10C , in the open state of the check valve  41 , for example when subjected to an upstream pressure (i.e., a pressure applied by a fluid flowing from the inlet  20  to the outlet  25 ), the check valve  400  permits fluid flow in the forward direction (direction of inlet port  20  to outlet port  25 ). During operation, fluid may enter the check valve  400  via the inlet  20 , and flow through the filter member  26  where it is filtered to trap the undesirable particulate matter, and into the cavity  30 . Any grit or other undesirable particulate matter larger in size than the pores of the filter member  26  may be trapped in the filter member  40 , and prevented from passing downstream to the valve member  41 . The upstream pressure (i.e., pressure applied by fluid flowing from the inlet  20  to the outlet  25 ) applied to the valve member  41  causes the valve member  41  to bow or bend downwards at the outer edges thereof and deflect away from the sealing surface  42 . 
     In some embodiments, the upstream pressure applied by the fluid flowing from the inlet  20  to the outlet which places check valve  400  in the open state may cause the valve member  41  to be displaced from its mounting position on the support portion  34 . In particular, a central axis X 4  of the valve member  41  may be misaligned with the central longitudinal axis X 1  of the check valve such that the valve member  41  contacts the downstream internal surface  59  of the upper housing  13  as discussed above. The aforementioned configuration of the valve member  41  with the castellated feet  24  having the curved friction ribs  43  is advantageous in that since the friction ribs  43  protrude radially outward a greater extent than an outer surface of the castellated feet  24 , when the check valve  100  is in the open state where fluid flows from the inlet  20  towards the outlet  25  and contacts the valve member  41 , the valve member  41  with the curved friction ribs  43  is displaced so as to follow a radial curved trajectory path away from the downstream internal surface  59  of the upper housing  13 . In this manner the curved friction ribs  43  further separate the valve member  41  from the downstream internal surface  59  of the upper housing  13 . Since contact between the valve member  41  and the downstream internal surface is minimized in this way, friction between the valve member  41  and the downstream internal surface  59  of the upper housing  13  is also minimized. 
     Various examples of aspects of the disclosure are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the subject technology. Identification of the figures and reference numbers are provided below merely as examples for illustrative purposes, and the clauses are not limited by those identifications. 
     Clause 1: A check valve, comprising: an upper housing defining an inlet of the check valve; a lower housing defining an outlet of the check valve; a cavity interposed between and defined by the upper and lower housings for fluidly connecting the inlet and the outlet; and a valve member mounted in the cavity to selectively permit fluid flow in a first direction, and prevent fluid backflow in a second direction opposite to the first direction, the valve member comprising a valve body and a valve stem portion extending axially through a central axis of the valve body. 
     Clause 2: The check valve of Clause 1, further comprising a plurality of feet extending longitudinally from an outer circumferential perimeter of the valve body. 
     Clause 3: The check valve of Clause 2, wherein adjacent pairs of the feet each define a recessed flow portion through which fluid entering the cavity flows from the upper housing into the lower housing. 
     Clause 4: The check valve of Clause 1, further comprising a filter member coupled to an inner surface of the upper housing, the filter member being disposed upstream of the valve member. 
     Clause 5: The check valve of Clause 1, wherein: the lower housing comprises a support portion disposed in the cavity at a central portion thereof, a central axis of the support portion being aligned with a central longitudinal axis of the check valve; and the valve member is configured to be mounted and supported on the support portion. 
     Clause 6: The check valve of Clause 1, wherein: the upper housing comprises an internal surface and an external surface, the internal surface including an upstream internal surface and a downstream internal surface; and the downstream internal surface of the upper housing includes a projection extending into the cavity, the projection being circularly disposed about a central axis of the valve member. 
     Clause 7: The check valve of Clause 6, wherein: a sealing surface is defined at a distal end of the projection; and in a closed state, the valve member is configured to contact the sealing surface to limit fluid flow past the sealing surface. 
     Clause 8: The check valve of Clause 7, wherein: when an upstream pressure is applied to the valve member, the valve member is configured to deflect away from the sealing surface to fluidly communicate the inlet and the cavity; and when a downstream pressure is applied to the valve member, the valve member is configured to deflect towards the sealing surface to block the fluid communication between the inlet and the cavity, and restrict backflow of the fluid from the outlet to the inlet. 
     Clause 9: A check valve, comprising: an upper housing defining an inlet of the check valve; a lower housing axially coupled to the upper housing and comprising an outlet of the check valve; a cavity interposed between and defined by the upper and lower housings for fluidly connecting the inlet and the outlet; and a flexible valve member mounted in the cavity to selectively permit fluid flow in a first direction, and prevent fluid backflow in a second direction opposite to the first direction, the flexible valve member comprising a body having a plurality of longitudinally extending feet disposed about an outer circumferential perimeter of the body. 
     Clause 10: The check valve of Clause 9, wherein: the upper housing comprises an internal surface and an external surface, the internal surface including an upstream internal surface and a downstream internal surface; and the upstream internal surface comprises a plurality of longitudinally extending ribs, the longitudinally extending ribs being radially spaced apart on the upstream internal surface about a central longitudinal axis of the check valve, and protruding radially inward from the upstream internal surface. 
     Clause 11: The check valve of Clause 10, further comprising a filter member mounted in the upper housing and disposed between the longitudinally extending ribs and the flexible valve member. 
     Clause 12: The check valve of Clause 11, wherein the filter member is positioned spaced apart from and disposed with a gap between the filter member and distal ends of the longitudinally extending ribs to maximize surface area for fluid flow from the inlet into the cavity. 
     Clause 13: The check valve of Clause 11, wherein: the downstream internal surface of the upper housing includes a projection extending into the cavity, the projection being circularly disposed about a central axis of the flexible valve member, and a distal end of the projection defining a sealing surface; and in a closed state, the valve member is configured to contact the sealing surface to limit fluid flow past the sealing surface. 
     Clause 14: The check valve of Clause 13, wherein: when a downstream pressure is applied to the valve member, the valve member is configured to deflect towards the sealing surface to block fluid communication between the inlet and the cavity, and restrict backflow of the fluid from the outlet to the inlet; and the longitudinally extending ribs are configured to support the valve member and to limit an extent to which the valve member stretches the filter member when the valve member is subjected to excessive back pressure. 
     Clause 15: The check valve of Clause 9, wherein the valve member comprises a valve body and a stem portion extending through a central axis of the valve body for supporting the valve member in the lower housing. 
     Clause 16: The check valve of Clause 9, wherein each of the longitudinally extending feet comprises at least one curved friction rib extending radially outward from an outer surface of a respective longitudinally extending foot of the plurality of longitudinally extending feet. 
     Clause 17: The check valve of Clause 16, wherein when a central axis of the valve member is misaligned with a central longitudinal axis of the check valve such that the valve member contacts an internal surface of the upper housing and the check valve is in a closed state, a surface area of contact of the valve member with the internal surface of the upper housing is limited to a surface area of the at least one friction rib contacting the internal surface. 
     Clause 18: The check valve of Clause 17, wherein the at least one friction rib contacting the internal surface of the upper housing comprises a maximum of two friction ribs. 
     Clause 19: The check valve of Clause 16, wherein when a central axis of the valve member is misaligned with a central longitudinal axis of the check valve such that the valve member contacts an internal surface of the upper housing and the check valve is in an open state with fluid flowing from the inlet towards the outlet, the curved friction ribs are displaced to follow a radial curved trajectory path away from the internal surface of the curved rib to further separate the valve from the internal surface of the upper housing. 
     Clause 20: A flexible valve member of a check valve, the flexible valve member comprising: a valve body; and a plurality of feet disposed about and extending longitudinally from an outer circumferential perimeter of the valve body. 
     Clause 21: The check valve of Clause 20, further comprising a valve stem portion extending axially through a central axis of the valve body. 
     Clause 22: The check valve of Clause 20, further comprising each of the feet comprises a curved friction rib extending radially outward from an outer surface of the respective foot. 
     The present disclosure is provided to enable any person skilled in the art to practice the various aspects described herein. The disclosure provides various examples of the subject technology, and the subject technology is not limited to these examples. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. 
     A reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. Pronouns in the masculine (e.g., his) include the feminine and neuter gender (e.g., her and its) and vice versa. Headings and subheadings, if any, are used for convenience only and do not limit the invention. 
     The word “exemplary” is used herein to mean “serving as an example or illustration.” Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. In one aspect, various alternative configurations and operations described herein may be considered to be at least equivalent. 
     As used herein, the phrase “at least one of” preceding a series of items, with the term “or” to separate any of the items, modifies the list as a whole, rather than each item of the list. The phrase “at least one of” does not require selection of at least one item; rather, the phrase allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrase “at least one of A, B, or C” may refer to: only A, only B, or only C; or any combination of A, B, and C. 
     A phrase such as an “aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. An aspect may provide one or more examples. A phrase such as an aspect may refer to one or more aspects and vice versa. A phrase such as an “embodiment” does not imply that such embodiment is essential to the subject technology or that such embodiment applies to all configurations of the subject technology. A disclosure relating to an embodiment may apply to all embodiments, or one or more embodiments. An embodiment may provide one or more examples. A phrase such an embodiment may refer to one or more embodiments and vice versa. A phrase such as a “configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A configuration may provide one or more examples. A phrase such a configuration may refer to one or more configurations and vice versa. 
     In one aspect, unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. In one aspect, they are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain. 
     It is understood that the specific order or hierarchy of steps, or operations in the processes or methods disclosed are illustrations of exemplary approaches. Based upon implementation preferences or scenarios, it is understood that the specific order or hierarchy of steps, operations or processes may be rearranged. Some of the steps, operations or processes may be performed simultaneously. In some implementation preferences or scenarios, certain operations may or may not be performed. Some or all of the steps, operations, or processes may be performed automatically, without the intervention of a user. The accompanying method claims present elements of the various steps, operations or processes in a sample order, and are not meant to be limited to the specific order or hierarchy presented. 
     All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112 (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” Furthermore, to the extent that the term “include,” “have,” or the like is used, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim. 
     The Title, Background, Summary, Brief Description of the Drawings and Abstract of the disclosure are hereby incorporated into the disclosure and are provided as illustrative examples of the disclosure, not as restrictive descriptions. It is submitted with the understanding that they will not be used to limit the scope or meaning of the claims. In addition, in the Detailed Description, it can be seen that the description provides illustrative examples and the various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed configuration or operation. The following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter. 
     The claims are not intended to be limited to the aspects described herein, but are to be accorded the full scope consistent with the language of the claims and to encompass all legal equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of 35 U.S.C. § 101, 102, or 103, nor should they be interpreted in such a way.