Abstract:
A valve with a flow adjustment device in the form of a valve stem travel limiter includes a removable and reversible collar having a passage therethrough to receive a valve stem having a shoulder, the passage further includes two bores having different diameters. The flow adjustment device may be assembled to a valve stem to permit two different predetermined valve stem travel limits.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The disclosure relates generally to control valves having a valve stem movable for flow rate adjustment and, more particularly, to travel limiters for such valve stems to adjust maximum available flow rate. 
       BACKGROUND 
       [0002]    Typically, a control valve includes a fluid inlet passage coupled through an orifice to a fluid outlet passage and a closure member disposed in the orifice, which controls the amount of fluid flow therethrough. The closure member may include a valve plug having a surface which engages the orifice forming a valve seat. During operation of a process control system, a process controller may issue a command signal to a control valve to move the valve plug toward or away from engagement with the valve seat to provide a desired fluid flow through the orifice and, therefore, the control valve. 
         [0003]    Control valves typically experience variable process conditions during their lifetime. A gas well, for example, may have high pressure when first drilled, but decreasing pressure over time. To maintain constant fluid flow as pressure decreases, the valve must either be disassembled to install a valve seat having a larger flow passage or must be adjusted to allow the valve plug to travel farther from the valve seat to open more port area. 
         [0004]    Thus, as a first alternative, to ensure that the valve will achieve the desired flow parameters, separate sets of valve plugs and valve seats may be installed. However, replacement of a valve plug and/or valve seat can necessitate disassembly and reassembly of the valve, which results in additional labor, and additional time the control valve is out of service. Accordingly, it is desirable to be able to achieve a plurality of desired flow parameters by using a single valve plug and a single valve seat. 
         [0005]    There are devices which work in conjunction with a valve stem to provide multiple stem travel limits, such as are shown in U.S. Pat. No. 6,905,108. However, the known devices tend to be fairly expensive and difficult to remove and install. This may be due to the tendency to require serrations or threads along the valve stem, as well as along the internal surface of the travel limiting device which engages the valve stem. Also, the devices tend to require removable bolts to fasten pieces together, which may create problems concerning adequate access for manipulation of tools to assemble and disassemble the device, as well as having to deal with multiple loose parts which require care in handling so as not to drop them, while at the same time the difficulty of achieving proper thread alignment when installing bolts, etc. 
         [0006]    The more difficult and time consuming manipulation involved with the prior art devices can be particularly challenging when an operator is wearing gloves, such as may be necessary in a cold environment. Given that control valves often are directly mounted on a well head and must cycle, making a change with the prior art devices also tends to require that the system be shut down to avoid the normal movement of the valve stem when the control valve cycles. The time required to remove the prior art devices also is important when an operator needs to completely remove the device, such as to allow the valve to be flushed. Thus, it would be preferable if each maximum flow rate change and flushing operation could be accomplished with less downtime of the control valve, resulting in greater productivity. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with one example, an apparatus for limiting the travel of a valve stem is provided in a valve having a housing that has a fluid inlet passage and a fluid outlet passage, with an orifice disposed between the fluid inlet passage and the fluid outlet passage. The apparatus further includes a valve plug adapted to move with respect to the orifice to vary the flow of fluid between the fluid inlet passage and the fluid outlet passage, a valve stem connected to the valve plug, with the valve stem having a shoulder disposed along a length of the valve stem that is disposed outside of the housing. The apparatus also includes a valve flow adjustment device having concentric first and second bores having respective different diameters, the valve flow adjustment device being removably connected to the valve stem and engageable with the shoulder, such that the valve flow adjustment device provides two preselected positions that limit the valve stem travel and correspond to two different maximum flow capacities of the valve. 
         [0008]    In accordance with another example, a valve flow adjustment device includes a valve stem having a shoulder and a portion of the valve stem extending above the shoulder. The device further includes a removable collar having a passage therethrough formed by concentric first and second bores, the first bore having a first diameter and the second bore having a relatively larger second diameter. The collar also slidably engages the portion of the valve stem extending above the shoulder, and has two preselected positions for engagement with the shoulder with the two preselected positions being adapted to limit movement of the valve stem to two different maximum travel positions. 
         [0009]    In yet another example, a valve flow adjustment device includes a valve stem having a shoulder and a portion of the valve stem extending above the shoulder. The device further includes a collar having at least two portions that when joined form a longitudinal passage therethrough having concentric first and second bores, the first bore having a first diameter and the second bore having a relatively larger second diameter, and a radially extending transition wall where the first and second bores meet within the collar. The device also includes a connector adapted to join the at least two collar portions to slidably engage the portion of the valve stem extending above the shoulder. 
         [0010]    With the example constructions, a flow adjustment device is provided that limits the travel of a valve stem. The device may include one or more pieces that form a removable, reversible collar around the valve stem. The collar has a passage therethrough having two different bore sizes, with each open to a respective end of the collar. The bores can be formed by having their features cast, molded or machined into the one or more pieces that form the collar. In accordance with the valve flow adjustment device, the flow adjustment device may be assembled to the valve stem to permit two different predetermined stem travel limits. 
         [0011]    The valve stem requires a shoulder to engage the removable collar, but no special machining or formation of threads or concentric grooves. Thus, the shoulder may be formed in a variety of ways such as, for example, by a change in valve stem diameter, by a press fit pin at least partially protruding from the valve stem, or by a stop ring inserted in a groove around the valve stem. 
         [0012]    Having a shoulder on the valve stem permits the collar to simply be installed in two different end-to-end configurations to vary the valve stem travel between two different predetermined settings. Depending on the orientation of the collar, if the relatively smaller bore is oriented toward the shoulder, it will contact the shoulder and limit the valve stem travel based on the full height of the collar. Alternatively, if the larger bore is oriented toward the shoulder, the shoulder will contact a transition wall formed where the passage changes from the first bore diameter to the second bore diameter, thus limiting the travel by less than the full height of the collar. Thus, the collar may be flipped end-to-end, or inverted, and reinstalled to adjust between the two predetermined valve stem travel limits. 
         [0013]    The collar may be held in place via a snap fit, or via other means, such as a spring clip, a latch mechanism, or other fasteners, such as a holding screw or the like. Advantageously, the fastening mechanism(s) may be conveniently made to remain attached to the collar at all times, thereby eliminating the need for loose bolts or screws, and some of the special machining and assembly techniques associated therewith. In turn, the device can be quite small and compact, allowing for shorter, lighter and less expensive valve assemblies having fewer parts. Such devices will require less time to change and, therefore, are more likely to permit rapid changes during normal system operation, between strokes of the valve stem. 
         [0014]    Thus, a flow adjustment device is provided that limits the travel of a valve stem. The device provides two different travel limits, which correspond to two different predetermined positions that may be achieved with respect to a maximum valve stem travel and thereby two different maximum flow characteristics for the valve. 
         [0015]    The device minimizes the drawbacks of the prior art while permitting a user to quickly change the maximum flow capacity of a valve or to decouple the flow adjustment device entirely via action taken outside of, or external to, the valve housing. Indeed, the operator may be able to make a flow adjustment between strokes of the valve stem, depending on the cycle time. This not only improves productivity by not having to shut down the fluid system, but also reduces operator time and effort, which can have a significant impact financially, as well as to the comfort of an operator working in inclement weather. 
         [0016]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and provided for purposes of explanation only, and are not restrictive of the invention, as claimed. Further features and objects of the present invention will become more fully apparent from the following description of the preferred embodiments and from the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a front view of a valve including a flow adjustment device. 
           [0018]      FIG. 2  is a cross-sectional view the valve of  FIG. 1 . 
           [0019]      FIG. 3  is a perspective view of a flow adjustment device mounted to a valve stem, in accordance with the example shown in  FIGS. 1 and 2 . 
           [0020]      FIG. 4  is a cross-sectional view of a collar of a flow adjustment device in accordance with the example shown in  FIGS. 1 and 2 , in a first travel limiting orientation. 
           [0021]      FIG. 5  is a cross-sectional view of a collar of a flow adjustment device in accordance with the example shown in  FIGS. 1 and 2 , in a second travel limiting orientation. 
           [0022]      FIG. 6  is a cross-sectional view of a first alternative collar of a flow adjustment device with an integral hinge and a captive screw fastener. 
           [0023]      FIG. 7  is a cross-sectional view of a second alternative collar of a flow adjustment device with a separable hinge and a captive screw fastener. 
           [0024]      FIG. 8  is a cross-sectional view of a third alternative collar of a flow adjustment device with an integral hinge and an integral fastener. 
           [0025]      FIG. 9  is a cross-sectional view of a fourth alternative collar of a flow adjustment device with a pair of identical portions, each having an integral fastener. 
           [0026]      FIG. 10  is an example of a first alternative valve stem shaft configuration with a perpendicular shoulder formed at a change in diameter along the valve stem shaft. 
           [0027]      FIGS. 11A and 11B  show an example of a second alternative valve stem shaft configuration with a shoulder formed via a pin through the shaft. 
           [0028]      FIGS. 12A and 12B  show an example of third alternative valve stem shaft configuration with a shoulder formed via a ring disposed in a groove. 
       
    
    
       [0029]    It should be understood that the drawings are not necessarily to scale. 
         [0030]    While other plan and section views are not included, the details such views would show are considered to be adequately shown in the present views or well within the comprehension of those skilled in the art in light of the present disclosure. It also should be understood that the present invention is not limited to the examples illustrated. 
       DETAILED DESCRIPTION 
       [0031]    Referring now to the drawings,  FIGS. 1 and 2  show an example of a control valve assembly  10  that includes a valve body  12  connected to a bonnet  14 . The bonnet  14 , in turn, is connected to a diaphragm casing  16 . The diaphragm casing  16  houses a sliding stem actuator, which may take other forms. The sliding stem actuator can be of any suitable type for use with control valves. The control valve assembly  10  may be joined by conventional methods, such as flange mounting, to fluid piping components within a larger process control system. 
         [0032]    Passing through the bonnet  14  is a valve stem  40 . Valve stem  40  is to be coupled to and driven by the sliding stem actuator at its proximal or upper end  42 . The valve stem  40  passes through the bonnet  14  and downward into the valve body  12 . In this example, coupled to the lower end  44  of the valve stem  40  is a valve plug  46 . The valve plug  46  includes a seating surface on its lower side. It will be appreciated that the valve stem  40  and valve plug  46  may be machined from a single piece, or may be formed in separate pieces for connection by common fastening methods. 
         [0033]    The valve body  12  includes an inlet passage  20  and an outlet passage  21 . A valve flow path  22  is formed between the inlet passage  20  and the outlet passage  21 . Disposed between the inlet passage  20  and outlet passage  21  is an orifice  24 . In this example, the orifice  24  receives a removable valve seat  26 , although it will be appreciated that a valve seat may be integrally formed in the valve body  12  at the orifice  24 . In this example, the valve plug  46  is shaped and sized to permit sealing engagement with the valve seat  26 . The valve plug  46  cooperates with the valve seat  26  in the orifice  24  to control the port area through which fluid may flow from the inlet passage  20  to the outlet passage  21 . Thus, the flow rate permitted through the control valve assembly  10  is controlled by the position of the valve stem  40  and, therefore, the position of the valve plug  46  relative to the valve seat  26 . In  FIG. 2 , the valve plug  46  is shown in a closed position, with the seating surface of the valve plug  46  fully engaging the valve seat  26 . 
         [0034]    In this example, the diaphragm casing  16  houses a common diaphragm control unit  30  having a diaphragm  32  that responds to control pressures to raise or lower a central mounting hub  34 , forming a sliding stem actuator in a manner well known in the art. It will be appreciated that alternative actuator units may be used. Also, the example flow adjustment device would be applicable to many types of valves having a valve stem, whether they are control valves, throttling valves or on/off valves. 
         [0035]    By virtue of the vertical movement of the central mounting hub  34  and its coupling to upper end  42  of the valve stem  40 , the valve stem  40  and valve plug  46  may move through a range of longitudinal travel in the control valve assembly  10 . This range of travel includes, at one extreme, being in a closed position when the valve plug  46  is in sealing engagement with the valve seat  26 , and at another extreme, being in a fully open, preselected maximum flow rate position when the valve stem  40  is moved to the full extent of its permitted travel. 
         [0036]    In this example, the bonnet  14  has an opening  50  by which an intermediate portion  52  of the valve stem  40  is accessible from outside of the control valve assembly  10 . In turn, the exposed intermediate portion  52  of the valve stem  40  has a shoulder  54  formed by an angled transition between a lower larger diameter portion  56  and an upper relatively smaller diameter portion  58 . Alternative shoulder formations will be discussed below with respect to examples shown in  FIGS. 10 ,  11 A and  11 B, and  12 A and  12 . To selectively limit the maximum upward travel of valve stem  40 , and thereby preselect a maximum flow rate position for the valve plug  46  relative to the valve seat  26 , a flow adjustment device  60  may be removably connected to valve stem  40  within the opening  50  in the bonnet  14 . 
         [0037]    The flow adjustment device  60  shown in the example in  FIGS. 1-5  includes a collar  62  and a clip  64  that may be combined to achieve two alternative valve stem travel limits. The collar  62  may be formed of one or more pieces and is shown as a two-piece assembly having a first collar portion  66  and a second collar portion  68 . First collar portion  66  and second collar portion  68  may be formed of a variety of materials, such as plastics, metals or the like, and may be molded or formed by other conventional means. The collar portions  66  and  68  also are configured to be joined to form the collar  62  which encircles the valve stem  40 . 
         [0038]    In the example shown, each of the collar portions  66  and  68  has an outer wall  70  having a groove or channel  72  formed therein, and has stepped inner walls  74  and  76  formed as semi-circular arcuate reliefs, with a wall  78  at the transition therebetween. The clip  64  is preferably formed of spring metal and in this example has a band shape that is complimentary to the channel  72  of the collar portions  66  and  68 . With this example configuration, the collar  62  may be formed by joining collar portions  66  and  68  when the clip  64  is installed in the channel  72  around both portions, as shown in  FIGS. 1 and 3 . For clearer viewing of the structure of the collar  62 , the clip  64  is removed in  FIGS. 2 ,  4  and  5 . 
         [0039]    When the collar portions  66  and  68  are held together to form the collar  62 , the semi-circular arcuate inner walls  74  and  76  of each of the collar portions  66  and  68  collectively form a passage  80  through collar  62  having a first bore  74   a  and a second bore  76   a . The inner diameter of first bore  74   a  is slightly larger than the outer diameter of the smaller diameter portion  58  of the valve stem  40 , but is smaller than the outer diameter of the larger diameter portion  56  of the valve stem  40 . The inner diameter of the second bore  76   a  is larger than the lager diameter portion  56  of the valve stem  40 . 
         [0040]    As can be best seen in  FIGS. 4 and 5 , the collar  62  may be installed on valve stem  40  in a first orientation wherein the smaller first bore  74   a  is open to a first end  82  of the collar  62 . In this orientation, due to the smaller first bore  74   a  being smaller than the larger diameter portion  56  of the valve stem  40 , the first end  82  of the collar  62  will engage the shoulder  54  on the valve stem  40 . As the valve stem  40  is moved upward its maximum travel will be limited when a second end  84  of the collar  62  engages an upper surface  86  of the opening  50  in the bonnet  14 . This is shown in  FIG. 4  and corresponds to a first preselected maximum travel of the valve stem  40 , and thereby to a first preselected maximum flow rate of the control valve assembly  10 . 
         [0041]    As shown in  FIG. 5 , a second preselected maximum travel of the valve stem  40 , and thereby a second preselected maximum flow rate may be selected if the clip  64  is removed and the collar portions  66  and  68  are temporarily removed, inverted and then reinstalled on the valve stem  40 . By effectively flipping over or inverting the collar  64  on the valve stem  40 , the relatively larger second bore  76   a  that is open to the second end  84  of the collar will allow the collar  62  to move downward on the valve stem  40  until the wall  78  in the collar  62  engages the shoulder  54 . In this second orientation, the valve stem  40  is permitted to move further upward until the first end  82  of the collar  62  engages the upper surface  86  of the opening  50  in the bonnet  14 . The further permitted movement in this second orientation allows the valve plug  46  to move further from the valve seat  26 , so as to open more port area, and thereby corresponds to a second preselected maximum flow rate of the control valve assembly  10 . 
         [0042]    In  FIG. 6 , an example of an alternative flow adjustment device  160  is shown in cross-section. In this example, the flow adjustment device  160  includes a collar  162  having collar portions  166  and  168  connected along one side by an integrally formed hinge  163 . The collar portions  166  and  168  are connected along their other sides by a fastener  165  that passes through an opening  167  in first collar portion  166  and is received in threaded bore  169  in second collar portion  168 . The opening  167  in the first collar portion  166  is in a recessed notch  171  and has a first threaded portion  173  and a second larger diameter unthreaded portion  175 . In this example, fastener  165  is formed with threads  177  at its distal end and a smaller diameter unthreaded shaft  179  between the distal threaded end and a cap head  181 . It will be appreciated that this arrangement provides a captive threaded fastener that may be tightened to draw collar portions  166  and  168  together and may be loosened to permit the collar  162  to be opened along one side and hinged along the opposite side at integral hinge  163 , while the fastener  165  remains coupled to the first collar portion  166 . The captive fastener  165  and integral hinge  163  keep the flow adjustment device  160  together as an assembly, even when being removed, thereby eliminating the concern of dropping fasteners. 
         [0043]    As with the example shown in  FIGS. 1-5 , each collar portion  166  and  168  of the alternative collar shown in  FIG. 6  has semi-circular arcuate inner walls  174  and  176 . When collar portions  166  and  168  are brought together, as shown in  FIG. 6 , they collectively form a passage  180  through collar  162  having a first bore  174   a  and a second relatively larger bore  176   a . A wall  178  is formed at the transition between the two bores. These features allow the alternative collar  162  to be used in two flow adjustment positions, in the same manner as the above described collar  62 . Given the integral hinge  163 , the collar  162  is particularly well suited for being produced as a single molded plastic piece. The fastener  165  may be made of any suitable material, such as metal, plastic or other composite materials. 
         [0044]    Turning to  FIG. 7 , a second alternative example of a flow adjustment device  260  is shown in cross-section. In this example, the flow adjustment device  260  includes a collar  262  having collar portions  266  and  268 , configured with corresponding arcuate portions to form a hinge  263 . The flow adjustment device  260  includes a fastener  265 , and is otherwise constructed in the same manner as collar portions  166  and  168 , and respective fastener  165 . Thus, each collar portion  266  and  268  of the second alternative collar shown in  FIG. 7  has semi-circular arcuate inner walls  274  and  276 . Accordingly, when collar portions  266  and  268  are brought together, as shown in  FIG. 7 , they collectively form a passage  280  through collar  262  having a first bore  274   a  and a second relatively larger bore  276   a . A wall  278  is formed at the transition between the two bores and these features allow the alternative collar  262  to be used similarly to the above examples in two flow adjustment positions. Also, given that the collar portions  266  and  268  are separable, the collar  262  may be manufactured using metal, plastic or other composite materials. As with the prior example, the fastener  265  may be made of any suitable material. 
         [0045]    A third alternative flow adjustment device  360  is shown in cross-section in  FIG. 8 . In this example, the flow adjustment device  360  includes a collar  362  having collar portions  366  and  368  connected along one side by an integrally formed hinge  363 . The collar portions  366  and  368  are connected along their other sides by a fastener  365 . Fastener  365  includes a notch  367  in first collar portion  366  that receives a latch arm  369  extending from second collar portion  368 . The notch  367  in the first collar portion  366  provides a recess and a lip  373  that engages a lug  375  on the latch arm  369 . In this example, fastener  365  can be engaged by bringing notch  367  and latch arm  369  together with a squeezing motion. Fastener  365  may be released by prying the latch arm  369  outward, so that lug  375  rides over and is free of lip  373 . 
         [0046]    It will be appreciated that this arrangement provides an integral fastener that may be engaged without use of any tools and may be removed by merely prying latch arm  369  to permit the collar  362  to be opened along the fastener side and hinged along the opposite side at integral hinge  363 . Thus, the example in  FIG. 8  permits fabrication of the flow adjustment device  360  in one piece. In this example, the integral hinge  363  and fastener  365  make the collar  362  and fastener  365  particularly well suited for being produced as a single molded plastic piece, or the like. 
         [0047]    As with the earlier examples shown in  FIGS. 1-7 , each collar portion  366  and  368  of the third alternative collar shown in  FIG. 8  has semi-circular arcuate inner walls  374  and  376 . When collar portions  366  and  368  are brought together, as shown in  FIG. 8 , they collectively form a passage  380  through collar  362  having a first bore  374   a  and a second relatively larger bore  376   a . A wall  378  is formed at the transition between the two bores. These features allow the alternative collar  362  to be used, similarly to the above examples, as a flow adjustment device in first and second flow adjustment positions. 
         [0048]    A fourth alternative flow adjustment device  460  is shown in cross-section in  FIG. 9 . In this example, the flow adjustment device  460  includes a collar  462  having collar portions  466  and  468 . Collar portions  466  and  468  are shown as being identical, and each has fastener portions  465  including a notch  467  with a lip  473  at one end, and a latch arm  469  with a lug  475  at the other end. The two collars may be snapped together or separated by prying a latch arm  469 , in a manner similar to that described with respect to the example in  FIG. 8 . It will be appreciated that this arrangement provides an integral fastener on each collar portion, making the collar portions  466  and  468  well suited for fabrication as plastic molded pieces, or the like. 
         [0049]    The collar portions  466  and  468  have arcuate inner walls  474  and  476 , similar to the examples shown in  FIGS. 1-8 , with a wall  478  formed at the transition between the two bores  474   a  and  476   a  that form a passage  480  when the collar portions  466  and  468  are coupled together. As with the above examples, these features allow this alternative collar  462  to be used in a similar manner to provide two flow adjustment positions. With respect to the above examples, it will be appreciated that the collar portion of a flow adjustment device may be formed or provided in a variety of ways. 
         [0050]      FIG. 10  presents a first alternative example of a formation of a shoulder on a valve stem for use with any of the above described collar portions of a flow adjustment device. In particular, a portion of a valve stem  140  is shown proximate a shoulder  154 . In this example, the shoulder  154  is formed as a wall at the transition from a lower larger diameter portion  156  to an upper relatively smaller diameter portion  158 . The diameters of the respective portions  156  and  158  are sized to cooperate with the example collars, as discussed with respect to the first example shown in  FIGS. 1-5 . The shoulder  154  may be made by machining or other fabrication to generate the difference in respective shaft diameters. 
         [0051]      FIGS. 11A and 11B  present a second alternative example of a formation of a shoulder on a valve stem for use with the above collar portions of a flow adjustment device. Here, the valve stem  240  has a common diameter both above and below a shoulder  254 . The shoulder  254  is formed by an aperture  255  through the valve stem  240  and a pin  257  inserted in the aperture  255 . At least one end of the pin  257  extends outward from the valve stem  240  for engagement with a collar portion. As will be appreciated by one of ordinary skill in the art, the pin  257  must be sized for retention in the aperture  255 , and of a length that is slightly less than the diameter of the inner relatively larger bore  76   a  of the collar portion, to properly provide two flow adjustment positions of the collar. The pin may be formed of a suitable relatively rigid material. 
         [0052]    A third alternative example of a formation of a shoulder on a valve stem is shown in  FIGS. 12A and 12B . In this example, a portion of a valve stem  340  is shown having a common shaft diameter, except for a groove  341 , formed such as by machining. As will be appreciated by one of ordinary skill in the art, the groove  341  receives a corresponding clip  343  to provide a shoulder  354  by means of a localized increase in diameter of the valve stem  340 . As noted with respect to the length of the pin  257  above, the clip  343  must have an outer diameter that is slightly smaller than the diameter of the inner relatively larger bore  76   a  of the collar portion. By using a clip  343 , this construction advantageously permits use of a shaft having a common diameter, except for the small groove  341 . With respect to the above examples, it will be appreciated that the shoulder on the valve stem may be formed or provided in a variety of ways. 
         [0053]    Thus, each of the above examples provides a simplified adjustment device that is external to the valve body, yet can create variable effective port sizes by adjusting the fully opened position of a valve plug relative to an orifice, via a valve stem travel limiter. This is a significant improvement over the conventional, more time consuming and, therefore, more expensive practice of having to open the control valve to replace the valve seat or valve plug to change the potential maximum port area, while also providing an improvement over other afore-mentioned more complicated and expensive valve stem and flow adjustment device combinations. 
         [0054]    Although certain example devices and articles of manufacture have been described herein, the scope of coverage is not limited thereto. It will be apparent to those skilled in the art that various modifications can be made in the design and construction of such flow adjustment devices and cooperating valve stems without departing from the scope or spirit of the present invention as claimed, and that the claims are not limited to the illustrated examples. Thus, while a flow adjustment device may be provided using any variety of suitable materials of construction, configurations, shapes and sizes for the components and methods of connecting the components, this application covers all devices and articles of manufacture fairly falling within the scope of the appended claims.