Patent Publication Number: US-2022228895-A1

Title: Dispensing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage Application of International Patent App. No. PCT/US2020/032885, filed May 14, 2020, which claims the benefit of U.S. Provisional Patent App. No. 62/848,408, filed May 15, 2019, the entire disclosures of both of which are hereby incorporated by reference as if set forth in their entirety herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to dispensing systems, and, more particularly, to a dispensing system including releasably connected first and second metering systems. 
     BACKGROUND 
     Metering and dispensing systems are used to emit a discrete amount of a particular material for dispensing on a substrate or storage in an appropriate container. Some such dispensing systems include the ability to meter and mix multiple types of materials in predetermined, accurate ratios. There are many applications for such a system, such as in the medical, automotive, or electronic fields. Typically, in systems where multiple materials must be metered and dispensed, multiple discrete metering systems are required. As a result, such dispensing systems require a greater number of parts, which requires a larger working inventory, increases servicing difficulty, and can decrease productivity. Additionally, servicing of such metering systems typically requires removing the system from the mounting position and disassembly elsewhere, further adding to operational costs and maintenance time. Also, when different material amounts are required, typically an operator of a dispensing system must replace the currently used metering system with a different metering system specially designed to dispense the desired material amount. 
     Therefore, there is a need for a dispensing system that incorporates multiple metering systems, and where portions of each of the metering system can be replaced or repaired without requiring removal of the entire metering system from the mounting location. 
     SUMMARY 
     An embodiment of the present disclosure is a dispensing system including a first metering system. The first metering system includes a first housing, a first metering rod at least partially disposed within the first housing, and a first assembly defining a first metering chamber and releasably connected to the first housing. The first metering rod is configured to linearly translate through the first metering chamber so as to dispense a discrete amount of a first material from the first metering chamber. The dispensing system also includes a second metering system including a second housing, a second metering rod at least partially disposed within the second housing, and a second assembly defining a second metering chamber and releasably connected to the second housing. The second metering rod is configured to linearly translate through the second metering chamber so as to dispense a discrete amount of a second material from the second metering chamber, and the first metering system is releasably connected to the second metering system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the appended drawings. The drawings show illustrative embodiments of the disclosure. It should be understood, however, that the application is not limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  illustrates a perspective view of a dispensing system according to an embodiment of the present disclosure; 
         FIG. 2  illustrates an alternative perspective view of the dispensing system shown in  FIG. 1 ; 
         FIG. 3  illustrates a cross-sectional view of the dispensing system shown in  FIG. 1 , taken along line  3 - 3  shown in  FIG. 2 ; 
         FIG. 4  illustrates an alternative perspective view of the dispensing system shown in  FIG. 1 ; 
         FIG. 5  illustrates an enlarged portion of the cross-sectional view of the dispensing system shown in  FIG. 3 ; 
         FIG. 6  illustrates a portion of a cross-sectional view of the dispensing system shown in  FIG. 1 , taken along line  6 - 6  shown in  FIG. 4 ; 
         FIG. 7  illustrates another portion of the cross-sectional view of the dispensing system shown in  FIG. 1 , taken along line  6 - 6  shown in  FIG. 4 ; 
         FIG. 8  illustrates a further portion of the cross-sectional view of the dispensing system shown in  FIG. 1 , taken along line  6 - 6  shown in  FIG. 4 ; 
         FIG. 9A  illustrates a cross-sectional view of the dispensing system shown in  FIG. 1 , taken along line  9 - 9  shown in  FIG. 4 , with the first and second needles in a first position; 
         FIG. 9B  illustrates a cross-sectional view of the dispensing system shown in  FIG. 1 , taken along line  9 - 9  shown in  FIG. 4 , with the first and second needles in a second position; 
         FIG. 10  illustrates a partially exploded view of a portion of the first and second metering systems of the dispensing system shown in  FIG. 1 ; 
         FIG. 11  illustrates a further partially exploded view of the first and second metering systems of the dispensing system shown in  FIG. 1 ; 
         FIG. 12  illustrates a cross-sectional view of portions of a dispensing system according to another embodiment of the present disclosure; 
         FIG. 13  illustrates a perspective view of a dispensing system according to another embodiment of the present disclosure; and 
         FIG. 14  illustrates a cross-sectional view of a portion of the dispensing system shown in  FIG. 13 , taken along line  14 - 14  shown in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Described herein is a dispensing system  10  that includes first and second metering systems  15   a ,  15   b  for metering shots of first and second materials, respectively. Certain terminology is used to describe the dispensing system  10  in the following description for convenience only and is not limiting. The words “right”, “left”, “lower,” and “upper” designate directions in the drawings to which reference is made. The words “inner” and “outer” refer to directions toward and away from, respectively, the geometric center of the description to describe the dispensing system  10  and related parts thereof. The words “upstream” and “downstream” refer to directions along the flow of material in relation to a particular component of the dispensing system  10 . The words “forward” and “rearward” refer to directions in a longitudinal direction  2  and a direction opposite the longitudinal direction  2  along the dispensing system  10  and related parts thereof. The terminology includes the above-listed words, derivatives thereof and words of similar import. 
     Unless otherwise specified herein, the terms “longitudinal,” “vertical,” and “lateral” are used to describe the orthogonal directional components of various components of the dispensing system  10 , as designated by the longitudinal direction  2 , lateral direction  4 , and vertical direction  6 . It should be appreciated that while the longitudinal and lateral directions  2 ,  4  are illustrated as extending along a horizontal plane, and the vertical direction  6  is illustrated as extending along a vertical plane, the planes that encompass the various directions may differ during use. 
     Referring to  FIGS. 1-3 , a dispensing system  10  for metering and dispensing first and second materials is shown. The dispensing system  10  can be utilized in a wide variety of applications, and as such the first and second materials can be acrylic, epoxy, silicone, grease, adhesive, urethane, PVC, varnish, etc. Though typically the first and second materials are different, the dispensing system  10  can be utilized in applications where the first and second materials are the same. The dispensing system  10  can include first and second metering systems  15   a ,  15   b , where the first and second metering systems  15   a ,  15   b  can be releasably connected to each other, as will be described below. 
     The first metering system  15   a  can include a linear actuator  20   a  configured to linearly translate a metering rod  82 , which will be described further below. The linear actuator  20   a  can include a housing  24  that extends from a first end  24   a  to a second end  24   b  opposite the first end  24   a  along the longitudinal direction  2 . The housing  24  can be substantially hollow, such that the housing  24  defines a cavity  26  configured to contain the operational components of the linear actuator  20   a . For example, an actuation module  28  of the linear actuator  20   a  can be disposed within the cavity  26  of the housing  24  at the first end  24   a . The actuation module  28  can comprise any suitable type of linear actuation device, such as a planetary ball screw, non-planetary ball screw, hydraulic cylinder, pneumatic cylinder, rack and pinion, etc. A rod  32  can extend from the actuation module  28 , such that that actuation module  28  is configured to linearly translate the rod  32  along the longitudinal direction  2 . The rod  32  can extend along the longitudinal direction  2  from a first end  32   a  to a second end  32   b  opposite the first end  32   a  along the longitudinal direction  2 . The rod  32  can be attached to the actuation module  28  at the first end  32   a , whereas the second end  32   b  of the rod  32  can be operably attached to the metering rod  82 . The second end  24   b  of the housing  24  can define a passage  36  extending therethrough, where the passage  36  can extend substantially along the longitudinal direction  2 . A bearing  40  can be disposed within the passage  36 , and the rod  32  can extend through the bearing  40 . The bearing  40  can be configured to guide the rod  32  and enable linear movement of the rod  32  along the longitudinal direction  2 . 
     Similarly, the second metering system  15   b  can include a second linear actuator  20   b  configured to linearly translate a metering rod  92 . Though the second metering system  15   b  will be described as similar to the first metering system  15   a  in many ways, it is contemplated that any number of differences can exist in operation between the first and second metering systems  15   a ,  15   b . The second linear actuator  20   b  can include a housing  54  that extends from a first end  54   a  to a second end  54   b  opposite the first end  54   a  along the longitudinal direction  2 . The housing  54  can be substantially hollow, such that the housing  54  defines a cavity  56  configured to contain the operational components of the second linear actuator  20   b . For example, an actuation module  58  of the second linear actuator  20   b  can be disposed within the cavity  56  of the housing  54  at the first end  54   a . The actuation module  58  can comprise any suitable type of linear actuation device, such as a planetary ball screw, non-planetary ball screw, hydraulic cylinder, pneumatic cylinder, rack and pinion, etc. A rod  62  can extend from the actuation module  58 , such that the actuation module  58  is configured to linearly translate the rod  62  along the longitudinal direction  2 . The rod  62  can extend along the longitudinal direction  2  from a first end  62   a  to a second end  62   b  opposite the first end  62   a  along the longitudinal direction  2 . The rod  62  can be attached to the actuation module  58  at the first end  62   a , whereas the second end  62   b  of the rod  62  can be operably attached to the metering rod  92 . The second end  54   b  of the housing  54  can define a passage  66  extending therethrough, where the passage  66  can extend substantially along the longitudinal direction  2 . A bearing  70  can be disposed within the passage  66 , and the rod  62  can extend through the bearing  70 . The bearing  70  can be configured to guide the rod  62  and enable linear movement of the rod  62  along the longitudinal direction  2 . 
     Each of the first and second metering systems  15   a ,  15   b , and specifically the linear actuators  20   a ,  20   b  of the first and second metering systems  15   a ,  15   b , can be in wired and/or wireless communication with a controller  72 . The controller  72  can be configured to control operation of the first and second linear actuators  20   a ,  20   b , based on predetermined operations or input provided by an operator of the dispensing system  10 . The controller  72  can comprise any suitable computing device configured to host a software application for monitoring and controlling various operations of the dispensing system  10  as described herein. It will be understood that the controller  72  can include any appropriate computing device, examples of which include a processor, a desktop computing device, a server computing device, or a portable computing device, such as a laptop, tablet, or smart phone. Specifically, the controller  72  can include a memory and a human-machine interface (HMI) device. The memory can be volatile (such as some types of RAM), non-volatile (such as ROM, flash memory, etc.), or a combination thereof. The controller  72  can include additional storage (e.g., removable storage and/or non-removable storage) including, but not limited to, tape, flash memory, smart cards, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, universal serial bus (USB) compatible memory, or any other medium which can be used to store information and which can be accessed by the controller  72 . The memory of the controller  72  can be configured to store and recall on demand various metering operations to be performed by the first and second metering systems  15   a ,  15   b.    
     The HMI device can include inputs that provide the ability to control the controller  72 , via, for example, buttons, soft keys, a mouse, voice actuated controls, a touch screen, movement of the controller  72 , visual cues (e.g., moving a hand in front of a camera on the controller  72 ), or the like. The HMI device can provide outputs via a graphical user interface, including visual information, such as the visual indication of the current conditions within the dispensing system  10 , as well as acceptable ranges for these parameters via a display. Other outputs can include audio information (e.g., via speaker), mechanically (e.g., via a vibrating mechanism), or a combination thereof. In various configurations, the HMI device can include a display, a touch screen, a keyboard, a mouse, a motion detector, a speaker, a microphone, a camera, or any combination thereof. The HMI device can further include any suitable device for inputting biometric information, such as, for example, fingerprint information, retinal information, voice information, and/or facial characteristic information, for instance, so as to require specific biometric information for accessing the controller  72 . 
     Continuing with  FIGS. 1-3 , the first metering system  15   a  includes a housing  80  attached to the housing  24 . The housing  80 , like the housing  24 , can define a hollow interior space  80   a . In the depicted embodiment, the housing  80  defines a solid body having a plurality of gaps extending therethrough, such that the components of the first metering system  15   a  located within the interior space  80   a  can be readily viewed. However, in some embodiments the housing  80  defines a substantially continuous body obscuring the components contained within the interior space  80   a . Further, the dispensing system  10  can include a cover  75  attached to the exterior of the housing  80  so as to obscure the components contained within the interior space  80   a , thus protecting these components from exterior forces or environmental contaminants. The cover  75  can be attached to the housing  80  via a plurality of fasteners  78 . However, the cover  75  can be attached to the housing  80  through other means, such as snap-fit, interference fit, etc. 
     The first metering system  15   a  can include a metering rod  82  at least partially disposed within the housing  80 . The metering rod  82  can have substantially elongate, cylindrical body that extends from a first end  82   a  to a second end  82   b  opposite the first end  82   a  along the longitudinal direction  2 . In one example, the metering rod  82  can be coated with a hard, low friction plating such as Scoreguard by Nordson Corporation, although alternative examples of the disclosure are not so limited. In one example, the metering rod  82  can be formed from carbide, although the metering rod  82  can be formed from any suitable alternative material. The first end  82   a  of the metering rod  82  can be attached to the rod  32 , such that the linear actuator  20   a  is configured to selectively linearly translate the metering rod  82  along the longitudinal direction  2 . To attach the metering rod  82  to the rod  32 , the first metering system  15   a  can include a coupling  84 . The coupling  84  can define a substantially cylindrical, hollow shell, though other embodiments of the coupling  84  are contemplated. A fastener  86  can be at least partially disposed within the coupling  84 , where the fastener  86  extends from the coupling  84  and engages the second end  32   b  of the rod  32 . The fastener  86  can threadedly engage the second end  32   b  of the rod  32 , though the fastener  86  can engage the rod  32  through other means as desired. At the opposite end, a pin  87  can extend through the coupling  84  along the vertical direction  6 . The pin  87  can also extend through the first end  82   a  of the metering rod  82  so as to couple the metering rod  82  to the coupling  84 , and thus the rod  32 . Though depicted as extending along the vertical direction  6 , the pin  87  can extend along any direction within a plane defined by the lateral and vertical directions  4 ,  6 , or along any direction including a longitudinal component. To secure the pin  87  to the coupling  84  and the metering rod  82 , a band  88  can be disposed around the coupling  84  and the opposing ends of the pin  87  after the pin  87  has connected the coupling  84  and metering rod  82 . The band  88  can comprise a substantially flexible and elastic material, such as rubber, though other materials are contemplated. Though a specific structure has been described for coupling the metering rod  82  to the rod  32 , other embodiments are contemplated. For example, the metering rod  82  and the rod  32  can be monolithic or integral with each other. 
     Like the first metering system  15   a , the second metering system  15   b  includes a housing  90  attached to the housing  24 . The housing  80 , like the housing  54 , can define a hollow interior space  90   a . In the depicted embodiment, the housing  90  defines a solid body having a plurality of gaps extending therethrough, such that the components of the second metering system  15   b  located within the interior space  90   a  can be readily viewed. However, in some embodiments the housing  90  defines a substantially continuous body obscuring the components contained within the interior space  90   a . Further, the cover  75  can be attached to the exterior of the housing  90  so as to obscure the components contained within the interior space  90   a , thus protecting these components from exterior forces or environmental contaminants. The cover  75  can be attached to the housing  90  via a plurality of fasteners  78 . However, the cover  75  can be attached to the housing  90  through other means, such as snap-fit, interference fit, etc. 
     The second metering system  15   b  can include a metering rod  92  at least partially disposed within the housing  90 . The metering rod  92  can have substantially elongate, cylindrical body that extends from a first end  92   a  to a second end  92   b  opposite the first end  92   a  along the longitudinal direction  2 . In one example, the metering rod  92  can be coated with a hard, low friction plating such as Scoreguard by Nordson Corporation, although alternative examples of the disclosure are not so limited. In one example, the metering rod  92  can be formed from carbide, although the metering rod  92  can be formed from any suitable alternative material. The first end  92   a  of the metering rod  92  can be attached to the rod  62 , such that the second linear actuator  20   b  is configured to selectively linearly translate the metering rod  92  along the longitudinal direction  2 . To attach the metering rod  92  to the rod  62 , the second metering system  15   b  can include a coupling  94 . The coupling  94  can define a substantially cylindrical, hollow shell, though other embodiments of the coupling  94  are contemplated. A fastener  96  can be at least partially disposed within the coupling  94 , where the fastener  96  extends from the coupling  94  and engages the second end  62   b  of the rod  62 . The fastener  96  can threadedly engage the second end  62   b  of the rod  62 , though the fastener  96  can engage the rod  62  through other means as desired. At the opposite end, a pin  97  can extend through the coupling  94  along the vertical direction  6 . The pin  97  can also extend through the first end  92   a  of the metering rod  92  so as to couple the metering rod  92  to the coupling  94 , and thus the rod  62 . Though depicted as extending along the vertical direction  6 , the pin  97  can extend along any direction within a plane defined by the lateral and vertical directions  4 ,  6 , or along any direction including a longitudinal component. To secure the pin  97  to the coupling  94  and the metering rod  92 , a band  98  can be disposed around the coupling  94  and the longitudinal ends of the pin  97  after the pin  97  has connected the coupling  94  and metering rod  92 . The band  98  can comprise a substantially flexible and elastic material, such as rubber, though other materials are contemplated. Though a specific structure has been described for coupling the metering rod  92  to the rod  62 , other embodiments are contemplated. For example, the metering rod  92  and the rod  62  can be monolithic or integral with each other. 
     Referring to  FIGS. 4-5 , the first metering system  15   a  can include an assembly  100  that defines the wetted components of the first metering system  15   a , i.e., the components of the first metering system  15   a  that receive a flow of the first material. The assembly  100  can include a housing  104  and a cap  108  configured to be releasably coupled to the housing  104  so as to secure components disposed within the housing  104 . The cap  108  can be engaged with the housing  104  through threaded attachment, though other means of attachment are contemplated, such as snap-fit, interference fit, etc. The housing  104  can define a flange  106  extending outwards from the housing  104 , particularly at the end adjacent the housing  24 . The flange  106  can be substantially square-shaped, though other shapes of the housing are contemplated. The flange  106  can define a plurality of bores  174  extending therethrough along the longitudinal direction  2 . In operation, the flange  106  can be utilized to couple the assembly  100  to the housing  24 . To couple the housing  104 , and thus the assembly  100 , to the housing  24 , the flange  106  can be placed into contact with the housing  24  and a plurality of fasteners  170  can be disposed through at least some of the bores  174  of the flange  106  so as to releasably couple the housing  104  to the housing  24 . Though it is contemplated that each of the bores  174  of the housing  104  can receive one of the fasteners  170 , it is contemplated that not all of the bores  174  can receive a fastener  170 , for reasons that will be discussed further below. Further, though a flange  106 , bores  174 , and a plurality of fasteners  170  are described as the devices utilized to couple the housing  104  to the housing  24 , it is contemplated that other devices can be utilized to couple the housing  104  to the housing  24  in other embodiments. 
     The housing  104  can define a metering chamber  130  extending along the longitudinal direction  2 , where the metering chamber  130  defines the area of the assembly  100  where the discrete amount of the first material will be received prior to being dispensed. The housing  104  can further define an inlet passage  146  configured to provide the first material to the metering chamber  130 , as well as an outlet passage  150  configured to receive the first material from the metering chamber  130 . Specifically, the inlet passage  146  can receive the first material from an input valve  300 , and the outlet passage  150  can receive the first material from the metering chamber  130  and provide the first material to an output manifold  500 , as will be described further below. The housing  104  can also define a flush passage  154  extending from the metering chamber  130  to the exterior of the housing  104 , thus providing an operator access to the metering chamber  130 , inlet passage  146 , and outlet passage  150  during a cleaning operation. During normal dispensing operations, a plug  158  can be disposed within the flush passage  154  to prevent the first material from escaping the assembly  100 . To perform a cleaning operation, an operator can unscrew or otherwise remove the plug  158  from the flush passage  154 , either by hand or through use of a tool. 
     The metering chamber  130  can be specifically defined by a sleeve  128  received within the housing  104 . The sleeve  128  can define a substantially elongate, hollow body extending along the longitudinal direction  2 , though other embodiments are contemplated. The assembly  100  can also include a seal retainer  112  received within the housing  104  and positioned between the sleeve  128  and the cap  108 . The seal retainer  112  can extend from a first end  112   a  to a second end  112   b  opposite the first end  112   a  along the longitudinal direction  2 . In particular, the seal retainer  112  can be in direct contact with the cap  108  at the first end  112   a  and the sleeve  128  the second end  112   b . As a result, the cap  108  and sleeve  128  can prevent the seal retainer  112  from moving within the housing  104  once the cap  108  has been securely attached to the housing  104 . When disposed within the housing  104 , the metering chamber  130  can extend from the seal retainer  112  to the outlet passage  150 . 
     The seal retainer  112  can define a central passage  114  configured to allow the metering rod  82  to extend therethrough, such that the metering rod  82  can extend through the housing  24 , through the seal retainer  112 , and into the metering chamber  130 . The central passage  114  can be sized such that the metering rod  82  is permitted to freely move linearly through the seal retainer  112  along the longitudinal direction  2 . At the first end  112   a , the seal retainer  112  can be configured to receive a seal  116  that extends around the metering rod  82  so as to create a fluid seal with the metering rod  82 . The seal  116  can prevent air from the housing  24  from entering the metering chamber  130  through and/or around the seal retainer  112 . At the opposite end, the second end  112   b  of the seal retainer  112  can be configured to receive two seals  124  that, like the seal  116 , extend around the metering rod  82  so as to create a fluid seal with the metering rod  82 . The seals  124  can prevent the first material from exiting the metering chamber  130  through the central passage  114  of the seal retainer  112  or around the seal retainer  112 . Though shown as receiving a single seal  116  at the first end  112   a  and two seals  124  at the second end  112   b , each of the first and second ends  112   a ,  112   b  of the seal retainer  112  can receive more or less seals than shown. In the depicted embodiment, the seal retainer  112  can define a first length L 1  measured along the longitudinal direction  2 . The length of the seal retainer  112  can be instrumental in dictating the size of the metering chamber  130 , as will be discussed further below. 
     The housing  104  can including at least one bore extending through its body from the metering chamber  130 . In the depicted embodiment, the housing  104  defines a rearward bore  138   a  and a forward bore  138   b  positioned between the rearward bore  138   a  and the outlet passage  150  along the longitudinal direction  2 . One of the forward and rearward bores  138   a ,  138   b  can receive a bleed valve  142 , while the other can receive a plug  144 . In the depicted embodiment, the rearward bore  138   a  receives the bleed valve  142 , while the forward bore  138   b  receives the plug  144 , though the opposite can be true in other embodiments. The plug  144  is configured to seal the forward bore  138   b  so as to prevent the first material from escaping the housing  104 . The bleed valve  142 , which can be positioned adjacent the second end  112   b  of the seal retainer  112 , can be configured to allow the first material to escape the housing  104  in the event of a component failure, such as leaking of one of the seals  124 . 
     Continuing with  FIGS. 4-5 , the second metering system  15   b  can include an assembly  200  that defines the wetted components of the second metering system  15   b , i.e., the components of the second metering system  15   b  that receive a flow of the second material. Though described as being substantially similar to the assembly  100 , the assembly  200  can have various differences in operation. The assembly  200  can include a housing  204  and a cap  208  configured to be releasably coupled to the housing  204  so as to secure components disposed within the housing  204 . The cap  208  can be engaged with the housing  204  through threaded attachment, though other means of attachment are contemplated, such as snap-fit, interference fit, etc. The housing  204  can define a flange  206  extending outwards from the housing  204 , particularly at the end adjacent the housing  54 . The flange  206  can be substantially square-shaped, though other shapes of the housing are contemplated. The flange  206  can define a plurality of bores  274  extending therethrough along the longitudinal direction  2 . In operation, the flange  206  can be utilized to couple the assembly  200  to the housing  54 . To couple the housing  204 , and thus the assembly  200 , to the housing  54 , the flange  206  can be placed into contact with the housing  54  and a plurality of fasteners  270  can be disposed through at least some of the bores  274  of the flange  206  so as to couple the housing  204  to the housing  54 . Though it is contemplated that each of the bores  274  of the housing  204  can receive one of the fasteners  270 , it is contemplated that not all of the bores  274  can receive a fastener  270 , for reasons that will be discussed further below. Further, though a flange  206 , bores  274 , and a plurality of fasteners  270  are described as the devices utilized to releasably couple the housing  204  to the housing  54 , it is contemplated that other devices can be utilized to couple the housing  204  to the housing  54  in other embodiments. 
     The housing  204  can define a metering chamber  230  extending along the longitudinal direction  2 , where the metering chamber  230  defines the area of the assembly  200  where the discrete amount of the second material will be received prior to being dispensed. The housing  204  can further define an inlet passage  246  configured to provide the second material to the metering chamber  230 , as well as an outlet passage  250  configured to receive the second material from the metering chamber  230 . Specifically, the inlet passage  246  can receive the second material from an input valve  400 , and the outlet passage  250  can receive the second material from the metering chamber  230  and provide the second material to the output manifold  500 , as will be described further below. The housing  204  can also define a flush passage  254  extending from the metering chamber  230  to the exterior of the housing  204 , thus providing an operator access to the metering chamber  230 , inlet passage  246 , and outlet passage  250  during a cleaning operation. During normal dispensing operations, a plug  258  can be disposed within the flush passage  254  to prevent the second material from escaping the assembly  200 . To perform a cleaning operation, an operator can unscrew or otherwise remove the plug  258  from the flush passage  254 , either by hand or through use of a tool. 
     The metering chamber  230  can be specifically defined by a sleeve  228  received within the housing  204 . The sleeve  228  can define a substantially elongate, hollow body extending along the longitudinal direction  2 , though other embodiments are contemplated. The assembly  200  can also include a seal retainer  212  received within the housing  204  and positioned between the sleeve  228  and the cap  208 . The seal retainer  212  can extend from a first end  212   a  to a second end  212   b  opposite the first end  212   a  along the longitudinal direction  2 . In particular, the seal retainer  212  can be in direct contact with the cap  208  at the first end  212   a  and the sleeve  228  at the second end  212   b . As a result, the cap  208  and sleeve  228  can prevent the seal retainer  212  from moving within the housing  204  once the cap  208  has been securely attached to the housing  204 . When disposed within the housing  204 , the metering chamber  230  can extend from the seal retainer  212  to the outlet passage  250 . 
     The seal retainer  212  can define a central passage  214  configured to allow the metering rod  92  to extend therethrough, such that the metering rod  92  can extend through the housing  54 , through the seal retainer  212 , and into the metering chamber  230 . The central passage  214  can be sized such that the metering rod  92  is permitted to freely move linearly through the seal retainer  212  along the longitudinal direction  2 . At the first end  212   a , the seal retainer  212  can be configured to receive a seal  216  that extends around the metering rod  92  so as to create a fluid seal with the metering rod  92 . The seal  216  can prevent air from the housing  54  from entering the metering chamber  230  through and/or around the seal retainer  212 . At the opposite end, the second end  212   b  of the seal retainer  212  can be configured to receive two seals  224  that, like the seal  216 , extend around the metering rod  92  so as to create a fluid seal with the metering rod  92 . The seals  224  can prevent the second material from exiting the metering chamber  230  through the central passage  214  of the seal retainer  212  or around the seal retainer  212 . Though shown as receiving a single seal  216  at the first end  212   a  and two seals  224  at the second end  212   b , each of the first and second ends  212   a ,  212   b  of the seal retainer  212  can receive more or less seals than shown. In the depicted embodiment, the seal retainer  212  can define a first length L 1  measured along the longitudinal direction  2 . As depicted, both the first and second seal retainers  112 ,  212  can define the first length L 1 , and as such the first and second metering chambers  130 ,  230  can be equally sized. However, in operation the first and second metering chambers  130 ,  230  can be differently sized, as will be described further below. 
     The housing  204  can including at least one bore extending through its body from the metering chamber  230 . In the depicted embodiment, the housing  204  defines a rearward bore  238   a  and a forward bore  238   b  positioned between the rearward bore  248   a  and the outlet passage  250  along the longitudinal direction  2 . One of the forward and rearward bores  248   a ,  248   b  can receive a bleed valve  242 , while the other can receive a plug  244 . In the depicted embodiment, the rearward bore  238   a  receives the bleed valve  242 , while the forward bore  248   b  receives the plug  244 , though the opposite can be true in other embodiments. The plug  244  is configured to seal the forward bore  238   b  so as to prevent the second material from escaping the housing  204 . The bleed valve  242 , which can be positioned adjacent the second end  212   b  of the seal retainer  212 , can be configured to allow the second material to escape the housing  204  in the event of a component failure, such as leaking of one of the seals  224 . 
     Continuing with  FIG. 6 , the input valve  300  will be described in greater detail. The input valve  300  can be releasably attached to the housing  104 , such as through a plurality of fasteners  306 , and configured to selectively provide the first material to the inlet passage  146 . However, other methods of releasably attaching the input valve  300  to the housing  104  are contemplated. Further, it is also contemplated that in other embodiments the input valve  300  can be integral with the housing  104 . The input valve  300  can comprise a body  304  and a cap  308  attached to an upper end of the body  304 . The cap  308  can be engaged with the body  304  through threaded attachment, though other means of attachment are contemplated, such as snap-fit, interference fit, etc. The body  304  and the cap  308  can define an actuation chamber  316  therebetween, where the actuation chamber  316  is configured to receive a piston  320 . The piston  320  can divide the actuation chamber  316  into an upper portion  316   a  above the piston  320  and between the piston  320  and the cap  308 , as well as a lower portion  316   b  below the piston  320  and between the piston  320  and the body  304 . A needle  336  can be attached to the piston  320  and extend through the lower portion  316   b  of the actuation chamber  316  and through the body  304  of the input valve  300 , as will be discussed further below. A seal  324  can be disposed around the piston  320  between the piston  320  and the body  304  so as to prevent air from leaking between the upper and lower portions  316   a ,  316   b  of the actuation chamber  316 . 
     The piston  320  can be configured to translate within the actuation chamber  316  along the vertical direction  6 . Translation of the piston  320  likewise causes upward and downward translation of the needle  336  along the vertical direction  6 . To move the piston  320 , and thus the needle  336  upwards, pressurized air can be provided to the lower portion  316   b  of the actuation chamber  316  through an air input  332  in fluid communication with the actuation chamber  316 . Specifically, the air input  332  can extend through the body  304  from the actuation chamber  316  to the outer surface of the body  304 , where the air input  332  can be connected to and receive pressurized air from a pressurized air source (not shown). The input valve  300  can include a seal  312 , such as an elastomeric O-ring, that is disposed between the body  304  and the cap  308 , so as to prevent pressurized air from leaking out of the lower portion  316   b  of the actuation chamber  316 . To move the piston  320 , and thus the needle  336  downwards, the input valve  300  can include a spring  328  disposed in the upper portion  316   a  of the actuation chamber  316 . The spring  328  can be biased between the upper surface of the piston  320  and the inner surface of the cap  308 , such that the spring  328  is in a constant state of compression and constantly exerting a downward force on the piston  320 . To move the piston  320  upwards, pressurized air must be provided to the lower portion  316   b  of the actuation chamber  316  to an extent that overcomes the downward force applied to the piston  320  by the spring  328 . However, when no pressurized air is provided to the lower portion  316   b  of the actuation chamber  316  or pressurized air is provided at an insufficient pressure, the spring  328  will force the piston  320  and needle  336  downwards. The cap  308  can function to limit the upward movement of the piston  320 , while the body  304  can function to limit the downward movement of the piston  320 . Though upward movement of the piston  320  in the depicted embodiment occurs due to pressurized air and downward movement occurs due to force applied by the spring  328 , in other embodiments upward force can be applied by a spring and downward force applied by pressurized air, or both upward and downward forces can be applied to the piston by pressurized air. 
     Opposite the actuation chamber  316 , the body  304  of the input valve  300  can define a material chamber  340 . A passage  342  can extend from the actuation chamber  316  to the material chamber  340 , where the needle  336  is configured to extend from the piston  320 , through the lower portion  316   b  of the actuation chamber  316 , through the passage  342 , and into the material chamber  340 . A seal  348  can be disposed around the needle  336  at the upper end of the passage  342 , where the seal  348  creates a fluid seal between the needle  336  and the body  304  while still allowing relative movement between the needle  336  and the seal  348 . The seal  348  can prevent pressurized air from leaking out of the lower portion  316   b  of the actuation chamber  316  and into the passage  342 . Two seals  344  can be positioned within the lower end of the passage  342  and around the needle  336  so as to create a fluid seal around the needle  336  to prevent the first material from leaking from the material chamber  340  through the passage  342 , while still allowing relative movement between the seals  344  and the needle  336 . 
     The material chamber  340  can define the portion of the input valve  300  configured to receive the first material from a first material source (not shown). The material chamber  340  can be defined by the body  304  of the input valve  300  and a nozzle cap  350  attached to the lower end of the body  304 . The nozzle cap  350  can be engaged with the body  304  through threaded attachment, though other means of attachment are contemplated, such as snap-fit, interference fit, etc. A seal  351  can be positioned between the nozzle cap  350  and the body  304  so as to prevent material from leaking out of the material chamber  340  between the nozzle cap  350  and the body  304 . A connector  360  can be attached to the nozzle cap  350 , where the connector  360  is configured to provide an interface between the nozzle cap  350  and a hose or other conveying means extending from the first material source to the nozzle cap  350 . The assembly  100  can further include a connector  162  configured to connect to both the housing  104  and the body  304  of the input valve  300 . The connector  162  can provide a fluid connection between the inlet passage  146  of the housing  104  and the material chamber  340  of the input valve  300 , as well as provide a fluid seal between the housing  104  and the input valve  300  to prevent the first material from leaking out of the assembly  100  as it flows from the input valve  300  to the housing  104 . As such, the first material enters the first metering system  15   a  through the connector  360 , and enters the housing  104  through the material chamber  340 , through the connector  162 , and into the inlet passage  146 . In one example, the connector  162  can be configured to selectively connect the input valve  300  to the housing  104  at different rotational angles about an axis that extends through the connector  162  along the lateral direction  4 . For example, the input valve  300  could be connected to the housing  104  at an angle that is rotated 90 degrees, 180 degrees, or 270 degrees about the axis relative to the position shown. 
     To control the flow of the first material into the first metering system  15   a , the input valve  300  can include a valve seat  356 , and the needle  336  can include a valve member  352 . Though one embodiment of the valve seat  356  and valve member  352  is shown, the valve seat  356  and valve member  352  can have various embodiments where contact between the valve seat  356  and the valve member  352  prevents the first material from flowing into the material chamber  340  from the connector  360 . In operation, the first needle  336  is configured to translate between a first position and a second position. To move the needle  336  into the first position, no pressurized air is provided to the lower portion  316   b  of the actuation chamber  316 , which causes the spring  328  to force the piston  320  downwards within the actuation chamber  316 . As a result, the needle  336  is forced downwards until the valve member  352  contacts the valve seat  356 . As such, in the first position, the first material is prevented from flowing from the connector  360  into the material chamber  340 , and ultimately to the metering chamber  130 . To move the needle  336  into the second position, pressurized air is provided to the lower portion  316   b  of the actuation chamber  316  to an extent so as to overcome the downward force exerted on the piston  320  by the spring  328 , which forces the piston  320  upwards within the actuation chamber  316 . As a result, the needle  336  is forced upwards until the piston  320  contacts the cap  308 , and the valve member  352  is spaced from the valve seat  356 . As such, in the second position, the first material is permitted to flow from the connector  360  into the material chamber  340 , and ultimately the metering chamber  130 . 
     Continuing with  FIG. 7 , the input valve  400  will be described in greater detail. Though the input valve  400  will be described as being very similar to the input valve  300 , in operation the input valves  300 ,  400  can differ as desired. The input valve  400  can be releasably attached to the housing  204 , such as through a plurality of fasteners  406 , and configured to selectively provide the second material to the inlet passage  246 . However, other methods of releasably attaching the input valve  400  to the housing  204  are contemplated. Further, it is also contemplated that in other embodiments the input valve  400  can be integral with the housing  204 . The input valve  400  can comprise a body  404  and a cap  408  attached to an upper end of the body  404 . The cap  408  can be engaged with the body  404  through threaded attachment, though other means of attachment are contemplated, such as snap-fit, interference fit, etc. The body  404  and the cap  408  can define an actuation chamber  416  therebetween, where the actuation chamber  416  is configured to receive a piston  420 . The piston  420  can divide the actuation chamber  416  into an upper portion  416   a  above the piston  420  and between the piston  420  and the cap  408 , as well as a lower portion  416   b  below the piston  420  and between the piston  420  and the body  404 . A needle  436  can be attached to the piston  420  and extend through the lower portion  416   b  of the actuation chamber  416  and through the body  404  of the input valve  400 , as will be discussed further below. A seal  424  can be disposed around the piston  420  between the piston  420  and the body  404  so as to prevent air from leaking between the upper and lower portions  416   a ,  416   b  of the actuation chamber  416 . 
     The piston  420  can be configured to translate within the actuation chamber  416  along the vertical direction  6 . Translation of the piston  420  likewise causes upward and downward translation of the needle  436  along the vertical direction  6 . To move the piston  420 , and thus the needle  436  upwards, pressurized air can be provided to the lower portion  416   b  of the actuation chamber  416  through an air input  432  in fluid communication with the actuation chamber  416 . Specifically, the air input  432  can extend through the body  404  from the actuation chamber  416  to the outer surface of the body  404 , where the air input  432  can be connected to and receive pressurized air from a pressurized air source (not shown). The input valve  400  can include a seal  412 , such as an elastomeric O-ring, that is disposed between the body  404  and the cap  408 , so as to prevent pressurized air from leaking out of the lower portion  416   b  of the actuation chamber  416 . To move the piston  420 , and thus the needle  436  downwards, the input valve  400  can include a spring  428  disposed in the upper portion  416   a  of the actuation chamber  416 . The spring  428  can be biased between the upper surface of the piston  420  and the inner surface of the cap  408 , such that the spring  428  is in a constant state of compression and constantly exerting a downward force on the piston  420 . To move the piston  420  upwards, pressurized air must be provided to the lower portion  416   b  of the actuation chamber  416  to an extent that overcomes the downward force applied to the piston  420  by the spring  428 . However, when no pressurized air is provided to the lower portion  416   b  of the actuation chamber  416  or pressurized air is provided at an insufficient pressure, the spring  428  will force the piston  420  and needle  436  downwards. The cap  408  can function to limit the upward movement of the piston  420 , while the body  404  can function to limit the downward movement of the piston  420 . Though upward movement of the piston  420  in the depicted embodiment occurs due to pressurized air and downward movement occurs due to force applied by the spring  428 , in other embodiments upward force can be applied by a spring and downward force applied by pressurized air, or both upward and downward forces can be applied to the piston by pressurized air. 
     Opposite the actuation chamber  416 , the body  404  of the input valve  400  can define a material chamber  440 . A passage  442  can extend from the actuation chamber  416  to the material chamber  440 , where the needle  436  is configured to extend from the piston  420 , through the lower portion  416   b  of the actuation chamber  316 , through the passage  442 , and into the material chamber  440 . A seal  448  can be disposed around the needle  436  at the upper end of the passage  442 , where the seal  448  creates a fluid seal between the needle  436  and the body  404  while still allowing relative movement between the needle  436  and the seal  448 . The seal  448  can prevent pressurized air from leaking out of the lower portion  416   b  of the actuation chamber  416  and into the passage  442 . Two seals  444  can be positioned within the lower end of the passage  442  and around the needle  436  so as create a fluid seal around the needle  436  to prevent the second material from leaking from the material chamber  440  through the passage  442 , while still allowing relative movement between the seals  444  and the needle  436 . 
     The material chamber  440  can define the portion of the input valve  400  configured to receive the second material from a second material source (not shown). The material chamber  440  can be defined by the body  404  of the input valve  400  and a nozzle cap  450  attached to the lower end of the body  404 . The nozzle cap  450  can be engaged with the body  404  through threaded attachment, though other means of attachment are contemplated, such as snap-fit, interference fit, etc. A seal  451  can be positioned between the nozzle cap  450  and the body  404  so as to prevent material from leaking out of the material chamber  440  between the nozzle cap  450  and the body  404 . A connector  460  can be attached to the nozzle cap  450 , where the nozzle cap  450  is configured to provide an interface between the nozzle cap  450  and a hose or other conveying means extending from the second material source to the nozzle cap  450 . The assembly  200  can further include a connector  262  configured to connect to both the housing  204  and the body  404  of the input valve  400 . The connector  262  can provide a fluid connection between the inlet passage  246  of the housing  104  and the material chamber  440  of the input valve  400 , as well as provide a fluid seal between the housing  204  and the input valve  400  to prevent the second material from leaking out of the assembly  200  as it flows from the input valve  400  to the housing  204 . As such, the second material enters the second metering system  15   b  through the connector  460 , and enters the housing  204  through the material chamber  440 , through the connector  262 , and into the inlet passage  246 . In one example, the connector  262  can be configured to selectively connect the input valve  400  to the housing  104  at different rotational angles about an axis that extends through the connector  262  along the lateral direction  4 . For example, the input valve  400  could be connected to the housing  104  at an angle that is rotated 90 degrees, 180 degrees, or 270 degrees about the axis relative to the position shown. 
     To control the flow of the second material into the second metering system  15   b , the input valve  400  can include a valve seat  456 , and the needle  436  can include a valve member  452 . Though one embodiment of the valve seat  456  and valve member  452  is shown, the valve seat  456  and valve member  452  can have various embodiments where contact between the valve seat  456  and the valve member  452  prevents the second material from flowing into the material chamber  440  from the connector  460 . In operation, the first needle  436  is configured to translate between a first position and a second position. To move the needle  436  into the first position, no pressurized air is provided to the lower portion  416   b  of the actuation chamber  416 , which causes the spring  428  to force the piston  420  downwards within the actuation chamber  416 . As a result, the needle  436  is forced downwards until the valve member  452  contacts the valve seat  456 . As such, in the first position, the second material is prevented from flowing from the connector  460  into the material chamber  440 , and ultimately to the metering chamber  230 . To move the needle  436  into the second position, pressurized air is provided to the lower portion  416   b  of the actuation chamber  416 , pressurized air is provided to the lower portion  416   b  of the actuation chamber  416  to an extent so as to overcome the downward force exerted on the piston  420  by the spring  428 , which forces the piston  420  upwards within the actuation chamber  416 . As a result, the needle  436  is forced upwards until the piston  420  contacts the cap  408 , and the valve member  452  is spaced from the valve seat  456 . As such, in the second position, the second material is permitted to flow from the connector  460  into the material chamber  440 , and ultimately the metering chamber  230 . 
     Now referring to  FIG. 8 , each of the first and second metering systems  15   a ,  15   b , and particularly the housings  104 ,  204  of the assemblies  100 ,  200  of the first and second metering systems  15   a ,  15   b , can be releasably attached to an output manifold  500 . The output manifold  500  can include a body  504 , as well as first and second passage  508   a ,  508   b  that extend through the body. The first passage  508   a  can be configured to receive the first material from the outlet passage  150  of housing  104  through a connector  166 , while the second passage  508   b  can be configured to receive the second material from the outlet passage  250  of the housing  204  through a connector  266 . The connectors  166 ,  266  can be configured to provide an interface between the housings  104 ,  204  and the output manifold  500 , as well as create a fluid seal between the housings  104 ,  204  and the output manifold  500 . The first and second passages  508   a ,  508   b  can be configured to redirect the flows of the first and second materials such that the flows are aligned with the input channels  576   a ,  576   b  of an output valve  540 , which will be discussed further below. The output manifold  500  can further include a first flush port  520   a  in fluid communication with the first passage  508   a , where the first flush port  520   a  is configured to provide access to first passage  508   a  during a cleaning operation. During normal operation, a plug  524  can be received within the first flush port  520   a  so as to create a fluid seal within the first flush port  520   a  and prevent the first material from leaking out of the first passage  508   a . Likewise, the output manifold  500  can include a second flush port  520   b  in fluid communication with the second passage  508   b , where the second flush port  520   b  is configured to provide access to the second passage  508   b  during a cleaning operation. During normal operation, a plug  528  can be received within the second flush port  520   b  so as to create a fluid seal within the second flush port  520   b  and prevent the second material from leaking out of the second passage  508   b.    
     As shown in  FIG. 2 , the dispensing system  10  can include first and second pressure sensors  532 ,  536  attached to the output manifold  500 . The first pressure sensor  532  can be in fluid communication with the first passage  508   a  such that the first pressure sensor  532  can be configured to detect a pressure of the first material flowing through the first passage  508   a . Likewise, the second pressure sensor  536  can be in fluid communication with the second passage  508   b  such that the second pressure sensor  536  can be configured to detect a pressure of the second material flowing through the second passage  508   b . Each of the first and second pressure sensors  532 ,  536  can be in wired and/or wireless communication with the controller  72 , and can each be configured to individually transmit a signal to the controller  72  that is indicative of the pressure of the first and second materials flowing within the respective first and second passages  508   a ,  508   b . The controller  72  can, via an HMI device, display these pressure values so that an operator of the dispensing system  10  can remain apprised of flow characteristics within the dispensing system  10  and adjust operational parameters of the dispensing system  10  accordingly. 
     Now referring to  FIGS. 8-9B , the dispensing system  10  can further include an output valve  540  connected to the output manifold  500 . In the depicted embodiment, the output valve  540  is releasably connected to the output manifold  500 , though in other embodiments the output valve  540  and the output manifold  500  can be integral with each other. The output valve  540  can be configured to receive the first and second materials from the output manifold  500  and selectively provide the first and second materials to a static mixer (not shown), as will be described further below. The output valve  540  can include a body  544  and a cap  552  attached to a rearward end of the body  544 . The cap  552  can be engaged with the body  544  through threaded attachment, though other means of attachment are contemplated, such as snap-fit, interference fit, etc. The body  544  and the cap  552  can define an actuation chamber  548  therebetween, where the actuation chamber  548  is configured to receive a piston  556 . The piston  556  can divide the actuation chamber  548  into a first portion  548   a  rearward of the piston  556  and between the piston  556  and the cap  552 , as well as a second portion  548   b  forward of the piston  556  and between the piston  556  and the body  544 . A first needle  566   a  and a second needle  566   b  can be attached to the piston  556  and extend through the second portion  548   b  of the actuation chamber  548  and through the body  544  of the output valve  540 , as will be discussed further below. A seal  560  can be disposed around the piston  556  between the piston  556  and the body  544  so as to prevent air from leaking between the first and second portions  548   a ,  548   b  of the actuation chamber  548 . 
     The piston  556  can be configured to translate within the actuation chamber  548  along the longitudinal direction  2 . Translation of the piston  556  likewise causes forward and rearward movement of the first and second needles  566   a ,  566   b  along the longitudinal direction  2 . To move the piston  556 , and thus the first and second needles  566   a ,  566   b  rearward, pressurized air can be provided to the second portion  548   b  of the actuation chamber  548  through a second air input  564   b  in fluid communication with the second portion  548   b . Specifically, the second air input  564   b  can extend through the body  544  from the actuation chamber  548  to the outer surface of the body  544 , where the second air input  564   b  can be connected to and receive pressurized air from a pressurized air source. To move the piston  556 , and thus the first and second needles  566   a ,  566   b  forwards, pressurized air can be provided to the first portion  548   a  of the actuation chamber  548  through a first air input  564   a  in fluid communication with the first portion  548   a . Specifically, the first air input  564   a  can extend through the body  544  from the actuation chamber  548  to the outer surface of the body  544 , where the first air input  564   a  can be connected to an receive pressurized air from a pressurized air source. The cap  552  can function to limit the rearward movement of the piston  556 , while the body  544  can function to limit the forward movement of the piston  556 . Though forward and rearward movement of the piston  556  in the depicted embodiment occurs due to pressurized air, in other embodiments other mechanisms can be utilized, such as springs. 
     Opposite the actuation chamber  548 , the body  544  of the output valve  540  can define first and second material chambers  582   a ,  582   b . A first passage  568   a  can extend from the actuation chamber  548  to the first material chamber  582   a , where the first needle  566   a  is configured to extend from the piston  556 , through the second portion  548   b  of the actuation chamber  548 , through the first passage  568   a , and through the first material chamber  582   a . A seal  569   a  can be disposed around the first needle  566   a  at the rearward end of the first passage  568   a , where the seal  569   a  creates a fluid seal between the first needle  566   a  and the body  544  while still allowing relative movement between the first needle  566   a  and the seal  569   a . The seal  569   a  can prevent pressurized air from leaking out of the lower portion  548   b  of the actuation chamber  548  and into the first passage  568   a . A seal  570   a  can be disposed around the first needle  566   a  at the forward end of the first passage  568   a , where the seal  570   a  creates a fluid seal around the first needle  566   a  while still allowing relative movement between the first needle  566   a  and the seal  570   a . The seal  570   a  can prevent the first material from leaking out of the first material chamber  582   a  and into the first passage  568   a.    
     Likewise, a second passage  568   b  can extend from the actuation chamber  548  to the second material chamber  582   b , where the second needle  566   b  is configured to extend from the piston  556 , through the second portion  548   b  of the actuation chamber  548 , through the second passage  568   b , and through the second material chamber  582   b . Though depicted as extending substantially parallel to the first passage  568   a , the first and/or second passages  568   a ,  568   b , and thus the first and second needles  566   a ,  566   b , can extend in other directions as desired. A seal  569   b  can be disposed around the second needle  566   b  at the rearward end of the second passage  568   b , where the seal  569   b  creates a fluid seal between the second needle  566   b  and the body  544  while still allowing relative movement between the second needle  566   b  and the seal  569   b . The seal  569   b  can prevent pressurized air from leaking out of the lower portion  548   b  of the actuation chamber  548  and into the second passage  568   b . A seal  570   b  can be disposed around the second needle  566   b  at the forward end of the second passage  568   b , where the seal  570   b  creates a fluid seal around the second needle  566   b  while still allowing relative movement between the second needle  566   b  and the seal  570   b . The seal  570   b  can prevent the second material from leaking out of the first chamber  568   a  and into the second passage  568   b.    
     The first material chamber  582   a  can define the portion of the output valve  540  configured to receive the first material from the output manifold  500 . The output valve  540  can include a first input channel  576   a  configured to partially receive a connector  512 , which is also configured to be partially received by the first passage  508   a  of the output manifold  500 . The connector  512  can be configured to provide an interface between the first passage  508   a  and the first input channel  576   a , as well as create a fluid seal between the output manifold  500  and the output valve  540  to prevent leaking of the first material. The first input channel  576   a  can extend from the outer surface of the body  544  to the first material chamber  582   a . As such, the first material enters the output valve  540  through the connector  512  from the first passage  508   a , through the first input channel  576   a , and into the first material chamber  582   a . The first material chambers  582   a  can be selectively in fluid communication with a first outlet chamber  584   a , as well as a first outlet channel  586   a  that extends from the first outlet chamber  584   a  to a mixer connector  588  that is configured to attach a static mixer (not shown) to the output valve  540  and provide the first material to the static mixer, as will be described further below. The first material chamber  582   a  can further be in fluid communication with a flush port  578   a  that extends from the first material chamber  582   a  to the outer surface of the body  544  of the output valve  540 , where the flush port  578   a  is configured to provide direct access to the first material chamber  582   a  in a cleaning operation. During normal operation, the flush port  578   a  can be sealed by a plug  580   a.    
     Similarly, the second material chamber  582   b  can define the portion of the output valve  540  configured to receive the second material from the output manifold  500 . The output valve  540  can include a second input channel  576   b  configured to partially receive a connector  516 , which is also configured to be partially received by the second passage  508   b  of the output manifold  500 . The connector  516  can be configured to provide an interface between the second passage  508   b  and the second input channel  576   b , as well as create a fluid seal between the output manifold  500  and the output valve  540  to prevent leaking of the second material. The second output channel  576   b  can extend from the outer surface of the body  544  to the second material chamber  582   b . As such, the second material enters the output valve  540  through the connector  516  from the second passage  508   b , through the second input channel  576   b , and into the second material chamber  582   b . The second material chamber  582   b  can be selectively in fluid communication with a second outlet chamber  584   b , as well as a second outlet channel  586   b  that extends from the second outlet chamber  584   b  to a mixer connector  588  that is configured to attach a static mixer (not shown) to the output valve  540  and provide the second material to the static mixer, as will be described further below. The second material chamber  582   b  can further be in fluid communication with a flush port  578   b  that extends from the second material chamber  582   b  to the outer surface of the body  544  of the output valve  540 , where the flush port  578   b  is configured to provide direct access to the second material chamber  582   b  in a cleaning operation. During normal operation, the flush port  578   b  can be sealed by a plug  580   b.    
     To control flow of the first and second materials from the output valve  540  to the static mixer, the output valve  540  can include seals  574   a ,  574   b , where the seals  574   a ,  574   b  are positioned at the forward end of the first and second material chambers  582   a ,  582   b , respectively. The seal  574   a  can be positioned within the first material chamber  582   a  opposite the seal  570   a , and can be spaced from the seal  570   a  by a spacer  572   a , where the spacer  572   a  can function to maintain a specified distance between the seals  570   a ,  574   a . Similarly, the seal  574   b  can be positioned within the second material chambers  582   b  opposite the seal  570   b , and can be spaced from the seal  570   b  by a spacer  572   b , where the spacer  572   b  can function to maintain a specified distance between the seals  570   b ,  574   b.    
     The first and second needles  566   a ,  566   b  can be designed so as to control the flow of the first and second materials to the first and second outlet channels  586   a ,  586   b , respectively, through selective engagement with the lip seals  574   a ,  574   b . Specifically, the first needle  566   a  can define a first portion  590   a  configured to attach to the piston  556  and extend through the first passage  568   a , narrow portion  592   a  extending from the first portion  590   a , and a valve portion  594   a  extending from the narrow portion  592   a  and opposite the first portion  590   a . Likewise, the second needle  566   b  can define a first portion  590   b  configured to attach to the piston  556  and extend through the second passage  568   b , a narrow portion  592   b  extending from the first portion  590   b , and a valve portion  594   b  extending from the narrow portion  592   b  and opposite the first portion  590   b . In operation, the first and second needles  566   a ,  566   b  are configured to translate between a first position and a second position. To move the first and second needles into the first position, pressurized air is provided to the second portion  548   b  of the actuation chamber  548  through the second air input  564   b , which causes the piston  556  to move rearwards through the actuation chamber  548 . As a result, the first and second needles  566   a ,  566   b  are moved rearwards until the valve portions  594   a ,  594   b  of the first and second needles  566   a ,  566   b  engage the seals  574   a ,  574   b , respectively. As such, in the first position, the first and second materials are prevented from flowing from the first and second material chambers  582   a ,  582   b  to the static mixer. 
     To move the first and second needles  566   a ,  566   b  into the second position, pressurized air is provided to the first portion  548   a  of the actuation chamber  548 , which forces the piston  556  to move forwards within the actuation chamber  548 . As a result, the first and second needles  566   a ,  566   b  are moved forwards, causing the valve portions  594   a ,  594   b  of the first and second needles  566   a ,  566   b  to be positioned within the first and second outlet chambers  584   a ,  584   b , respectively, and the narrow portions  592   a ,  592   b  of the first and second needles  566   a ,  566   b  to be laterally aligned with the seals  574   a ,  574   b , respectively. This smaller relative diameter of the narrow portions  592   a ,  592   b  provides a clearance between the seals  574   a ,  574   b  and the first and second needles  566   a ,  566   b , thus allowing the first and second materials to pass therebetween. As such, in the second position, the first and second materials are permitted to flow from the first and second material chambers  582   a ,  582   b  to the static mixer. Though the depicted output valve  540  includes operatively connected first and second needles  566   a ,  566   b , such that the first and second needles  566   a ,  566   b  are configured to transition between the first and second positions simultaneously, it is contemplated that in other embodiments, the first and second needles  566   a ,  566   b  can be transitioned between the first and second positions individually, either through use of an alternatively configured output valve or through use of multiple output valves. 
     In a dispensing operation, the dispensing system  10  can be utilized to meter and dispense discrete amounts of a first and second material. Initially, the first linear actuator  20   a  can translate the first metering rod  82  through the metering chamber  130  to a retracted position, in which the second end  82   b  of the metering rod  82  is disposed within the seal retainer  112 . The second linear actuator  20   b  can similarly translate the second metering rod  92  through the metering chamber  230  to a retracted position, in which the second end  92   b  of the metering rod  92  is disposed within the seal retainer  212 . When the metering rods  82 ,  92  are in the retracted position, the metering chambers  130 ,  230  can be unobstructed so as to receive discrete amounts of the first and second materials. 
     Simultaneous with or after transitioning the metering rods  82 ,  92  into the retracted position, the input valves  300 ,  400  can be configured to allow the first and second materials to flow into the metering chambers  130 ,  230 , respectively. To accomplish this, pressurized air can be provided to the lower portion  316   b  of the actuation chamber  316  of the input valve  300  to an extent that overcomes the downward force applied to the piston  320  by the spring  328 . This moves the piston  320  upwards through the actuation chamber  316 , and the needle  336  is transitioned from the first position to the second position, such that the valve member  352  is spaced from the valve seat  356 . As a result, the first material is permitted to flow from the connector  360  into the material chamber  340 , and ultimately the metering chamber  130 . Similarly, pressurized air can be provided to the lower portion  416   b  of the actuation chamber  416  of the input valve  400  to an extent that overcomes the downward force applied to the piston  420  by the spring  428 . This moves the piston  420  upwards through the actuation chamber  416 , and the needle  436  is transitioned from the first position to the second position, such that the valve member  452  is spaced from the valve seat  456 . As a result, the second material is permitted to flow from the connector  460  into the material chamber  440 , and ultimately the metering chamber  230 . 
     Once the first metering chamber  130  is filled with the first material and the second metering chamber  230  is filled with the second material, the input valves  300 ,  400  can be actuated to prevent the first and second materials from flowing into the metering chambers  130 ,  230 , respectively. To accomplish this, the operator of the dispensing system  10  can prevent pressurized air from being provided to the lower portion  316   b  of the actuation chamber  316  of the input valve  300 . As a result, the force applied to the piston  320  by the spring  328  moves the piston  320  downwards through the actuation chamber  316 , and the needle  336  is transitioned from the second position to the first position. In the first position, the valve member  352  engages the valve seat  356 , and the first material is prevented from flowing into the material chamber  340  from the connector  360 . Similarly, the operator of the dispensing system  10  can prevent pressurized air from being provided to the lower portion  416   b  of the actuation chamber  416  of the input valve  400 . As a result, the force applied to the piston  420  by the spring  428  moves the piston  420  downwards through the actuation chamber  416 , and the needle  436  is transitioned from the second position to the first position, such that the valve member  452  engages the valve seat  456 , and the second material is prevented from flowing into the material chamber  440  from the connector  460 . 
     When the first and second metering chambers  130 ,  230  are filled with the first and second materials, respectively, the metering rods  82 ,  92  can be actuated to force the discrete amounts of the first and second materials from the first and second metering chambers  130 ,  230 . In particular, the linear actuator  20   a  can translate the metering rod  82  forwards through the metering chamber  130  so as to dispense the discrete amount of the first material from the metering chamber  130 . Similarly, the second linear actuator  20   b  can translate the metering rod  92  forwards through the metering chamber  230  so as to dispense the discrete amount of the second material from the metering chamber  230 . The first and second materials can thus be forced to flow from the first and second metering chambers  130 ,  230 , through the output manifold  500 , and to the output valve  540 . 
     Prior to the metering rods  82 ,  92  forcing the discrete amounts of the first and second materials to the output valve  540 , the first and second needles  566   a ,  566   b  of the output valve  540  may be in the first position, in which the valve portions  594   a ,  594   b  of the first and second needles  566   a ,  566   b  engage the seals  574   a ,  574   b , respectively, thus preventing the first and second materials from flowing to the static mixer. Prior to or simultaneous with the first and second materials being forced to the output valve  540 , the first and second needles  566   a ,  566   b  can be transitioned to the second position, in which the valve portions  594   a ,  594   b  of the first and second needles  566   a ,  566   b  are positioned within the first and second outlet chambers  584   a ,  584   b , respectively, and the narrow portions  592   a ,  592   b  of the first and second needles  566   a ,  566   b  are laterally aligned with the seals  574   a ,  574   b , respectively. As a result, when the first and second needles  566   a ,  566   b  are in the second position, clearance between the seals  574   a ,  574   b  and the first and second needles  566   a ,  566   b , thus allows the first and second materials to pass therebetween from the first and second material chambers  582   a ,  582   b  to the static mixer, which can mix the first and second materials into a substantially homogenous mixture and provide the mixture to a dispenser. 
     Modularity 
     By combining the first and second metering systems  15   a ,  15   b  into a single dispensing system  10 , a two-component dispensing system  10  can be utilized to dispense the first and second materials, as opposed to multiple single-component dispensing systems. This allows for an operator to more easily service the dispensing system  10 , as well as keep fewer spare parts on hand. Referring to  FIG. 10 , the first and second metering systems  15   a ,  15   b  can be releasably coupled together to define the dispensing system  10 . In particular, the housing  80  can be releasably connected to the housing  90 , though it is contemplated that other components of the first and second metering systems  15   a ,  15   b  can be coupled together as desired. The dispensing system  10  can include a plurality of fasteners  99  that are configured to at least partially extend through the housings  80 ,  90 , so as to couple the housing  80  to the housing  90 , and thus the first metering system  15   a  to the second metering system  15   b . In the depicted embodiment, the plurality of fasteners  99  includes four fasteners  99 , with two fasteners coupling each end of the housing  80  to a corresponding end of the housing  90 . However, more or less fasteners  99  can be utilized as desired. In one embodiment, each of the fasteners  99  are bolts, though other types of fasteners are contemplated, such as screws, rods, etc. Further, it is contemplated that in other embodiments the first and second metering systems  15   a ,  15   b  can be coupled to each other through alternative features. 
     In addition to releasably coupling the first and second metering systems  15   a ,  15   b  to each other, the assembly  100  can be releasably coupled to the linear actuator  20   a , while the assembly  200  can be releasably coupled to the second linear actuator  20   b . As the assemblies  100 ,  200  define the components of each of the first and second metering systems  15   a ,  15   b  through which the first and second materials flow, the ability to detach the assemblies  100 ,  200  from the linear actuators  20   a ,  20   b , individually or together, allows the operator of the dispensing system  10  to repair, replace, or otherwise service aspects of the assemblies  100 ,  200  without removing the entire dispensing system  10  from its mounting location. This decreases the complexity of a maintenance operation and the time required to perform a maintenance operation. 
     Serviceability 
     Referring to  FIG. 11 , the assembly  100  can be attached to the linear actuator  20   a  through a plurality of fasteners  170  that extend through corresponding bores  174  of the flange  106  of the housing  104  and couple the housing  104  to the housing  80 . To detach the assembly  100  from the linear actuator  20   a , the operator can simply loosen the fasteners  170  sufficiently such that the fasteners  170  no longer attach to the housing  80 . As depicted, the flange  106  can include additional bores  176  that are not configured to receive a fastener  170 . For example, the flange  106  can define at least one additional bore  176  positioned between two bores  174  that are each configured to receive a fastener  170 . Once the fasteners  170  have been detached from the housing  80 , the additional bore  176  can be configured to receive a fastener  170  so as to contact, but not couple, the fastener  170  to the housing  80 . The operator can then use the fastener  170  to push the assembly  100  away from the housing  80  to detach the assembly  100  from the housing  80 , and in particular slide the metering rod  82  out of the metering chamber  130  and seal retainer  112 . The flange  106  can include any number of additional bores  176  as desired, such as one, two, three, or more than three additional bores  174 . Further, a tool (not shown) other than one of the fasteners  170  may be used by the operator to extend through the additional bore  176  and push the assembly away from the housing  80 . 
     Similar to the assembly  100 , the assembly  200  can be attached to the second linear actuator  20   b  through a plurality of fasteners  270  that extend through corresponding bores  274  of the flange  206  of the housing  204  and couple the housing  204  to the housing  90 . To detach the assembly  200  from the second linear actuator  20   b , the operator can simply loosen the fasteners  270  sufficiently such that the fasteners  270  no longer attach to the housing  90 . As depicted, the flange  206  can include additional bores  276  that are not configured to receive a fastener  270 . For example, the flange  206  can define at least one additional bore  276  positioned between two bores  274  that are each configured to receive a fastener  270 . Once the fasteners  270  have been detached from the housing  90 , the additional bore  276  can be configured to receive a fastener  270  so as to contact, but not couple, the fastener  270  to the housing  90 . The operator can then use the fastener  270  to push the assembly  200  away from the housing  90  to detach the assembly  200  from the housing  90 , and in particular slide the metering rod  92  out of the metering chamber  230  and seal retainer  212 . The flange  206  can include any number of additional bores  276  as desired, such as one, two, three, or more than three additional bores  274 . Further, a tool (not shown) other than one of the fasteners  270  may be used by the operator to extend through the additional bore  276  and push the assembly away from the housing  90 . Though fasteners  170 ,  270  are specifically described as attaching the assemblies  100 ,  200  to the linear actuators  20   a ,  20   b , other features can be utilized. 
     Dual Seals 
     The ability to decouple the assemblies  100 ,  200  from the linear actuators  20   a ,  20   b , respectively, allows the operator of the dispensing system to easily replace certain components of the assemblies  100 ,  200  without removing the entire dispensing system  10  from its mounting location. One particular aspect of the assemblies  100 ,  200  that can be replaced is the seal retainers  112 ,  212 . Referring to  FIG. 12 , a seal retainer  212 ′ according to another embodiment of the present disclosure will be described. The seal retainer  212 ′ can have similar features to the seal retainer  212  as previously described, and as a result such components will be labeled similarly. The seal retainer  212 ′ can be received within the housing  204  of the assembly  200  and positioned between the sleeve  228 ′ and the cap  208 . The seal retainer  212 ′ can be disposed within the housing  204  during an initial setup of the dispensing system  10 , or during a maintenance operation in which the assembly  200  is detached from the dispensing system  10 , as described above. The seal retainer  212 ′ can extend from a first end  212   a  to a second end  212   b  opposite the first end  212   a  along the longitudinal direction  2 . In particular, the seal retainer  212 ′ can be in direct contact with the cap  208  at the first end  212   a  and the sleeve  228 ′ the second end  212   b . As a result, the cap  208  and sleeve  228 ′ can prevent the seal retainer  212 ′ from moving within the housing  204  once the cap  208  has been securely attached to the housing  204 . When disposed within the housing  204 , the metering chamber  230 ′ can extend from the seal retainer  212 ′ to the outlet passage  250 . 
     The seal retainer  212 ′ can define a central passage  214  configured to allow the metering rod  92  to extend therethrough, such that the metering rod  92  can extend through the housing  54 , through the seal retainer  212 ′, and into the metering chamber  230 ′. The central passage  214  can be sized such that the metering rod  92  is permitted to freely move linearly through the seal retainer  212 ′ along the longitudinal direction  2 . At the first end  212   a , the seal retainer  212 ′ can be configured to receive a seal  216  that extends around the metering rod  92  so as to create a fluid seal with the metering rod  92 . The seal  216  can prevent air from the housing  54  from entering the metering chamber  230 ′ through and/or around the seal retainer  212 . At the opposite end, the second end  212   b  of the seal retainer  212 ′ can be configured to receive two seals  224  that, like the seal  216 , extend around the metering rod  92  so as to create a fluid seal with the metering rod  92 . The seals  224  can prevent the first material from exiting the metering chamber  230 ′ through the central passage  214  of the seal retainer  212 ′ or around the seal retainer  212 ′. Though shown as receiving a single seal  216  at the first end  212   a  and two seals  224  at the second end  212   b , each of the first and second ends  212   a ,  212   b  of the seal retainer  212 ′ can receive more or less seals than shown. Further, in embodiments utilizing the seal retainer  212 ′, the bleed valve  242  can be disposed within the forward bore  238   b  so as to be positioned adjacent the second end  212   b  of the seal retainer  212 . 
     As shown in  FIG. 12 , in contrast with the seal retainer  212 , the seal retainer  212 ′ can define a second length L 2  measured along the longitudinal direction  2 . The first and second lengths L 1 , L 2  are different, and thus the first and second metering chambers  130 ,  230 ′ are differently sized. By using a differently sized seal retainer  112 ,  212 ′, the operator of the dispensing system  10  can adjust the size of the metering chamber  130 ,  230 ′, and thus the volume of the material received by the metering chamber  130 ,  230 ′ and forced to the output valve  540  by the metering rod  82 ,  92 . As depicted, the second length L 2  can be about double the first length L 2 , such that that the metering chamber  230 ′ is about half the size of the metering chambers  130 ,  230 . Accordingly, the discrete amount of material dispensed by an assembly utilizing the seal retainer  212 ′ can be about half of the discrete amount of the material dispensed by an assembly utilizing the seal retainers  112 ,  212 . Though seal retainers  112 ,  212  having a first length L 1  and a seal retainer having a second length L 2  are shown, a dispensing system  10  can include seal retainers having various other lengths. For example, the dispensing system  10  can include seal retainers having lengths less than the second length L 2  or greater than the second length L 2 , depending on the volume of the material required to be dispensed by the dispensing system  10 . 
     Single Linear Actuator 
     Now referring to  FIG. 13 , another embodiment of a dispensing system  10 ′ will be shown. The dispensing system  10 ′ contains may similarities to the dispensing system  10 , and as such corresponding features will be similarly labeled. The dispensing system  10 ′ can include a single linear actuator  20  configured to linearly translate both metering rods  82 ,  92 , as will be described further below. The linear actuator  20  can include a housing  24  that extends from a first end  24   a  to a second end  24   b  opposite the first end  24   a  along the longitudinal direction  2 . The housing  24  can be substantially hollow, such that the housing  24  defines a cavity  26  configured to contain the operational components of the linear actuator  20 . For example, an actuation module  28  of the linear actuator  20  can be disposed within the cavity  26  of the housing  24  at the first end  24   a . The actuation module  28  can comprise any suitable type of linear actuation device, such as a planetary ball screw, non-planetary ball screw, hydraulic cylinder, pneumatic cylinder, rack and pinion, etc. A rod  32  can extend from the actuation module  28 , such that that actuation module  28  is configured to linearly translate the rod  32  along the longitudinal direction  2 . The rod  32  can extend along the longitudinal direction  2  from a first end  32   a  to a second end  32   b  opposite the first end  32   a  along the longitudinal direction  2 . The rod  32  can be attached to the actuation module  28  at the first end  32   a , whereas the second end  32   b  of the rod  32  can be operably attached to the metering rods  82 ,  92 . The second end  24   b  of the housing  24  can define a passage  36  extending therethrough, where the passage  36  can extend substantially along the longitudinal direction  2 . A bearing  40  can be disposed within the passage  36 , and the rod  32  can extend through the bearing  40 . The bearing  40  can be configured to guide the rod  32  and enable linear movement of the rod  32  along the longitudinal direction  2 . 
     A coupling assembly  600  can be disposed at the second end  32   b  of the rod  32  and can be configured to attach the rod  32  to the first and second metering rods  82 ,  92 . The coupling assembly  600  can include a first coupling member  602  configured to attach to the first and second metering rods  82 ,  92 , and a second coupling member  604  configured to attach to the rod  32 . To attach the first coupling member  602  to the first and second metering rods  82 ,  92 , the coupling assembly  600  can include a coupling bolt  608  configured to extend laterally through the first and second metering rods  82 ,  92 , as well as the first coupling member  602 . The coupling bolt  608  can also extend through the second coupling member  604  so as to couple the first and second coupling members  602 ,  604  together. To secure the coupling bolt  608  in place, one end of the coupling bolt  608  can threadedly engage a nut  612 . The fastener  86  can be utilized to couple the second coupling member  604  to the rod  32 . By coupling the rod  32  of the linear actuator  20  using the coupling assembly  600 , the linear actuator can be configured to simultaneously translate the first and second metering rods  82 ,  92  through the first and second metering chambers  130 ,  230 , respectively. 
     While various inventive aspects, concepts and features of the inventions may be described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects, concepts and features may be used in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present inventions. Still further, while various alternative embodiments as to the various aspects, concepts, and features of the inventions—such as alternative materials, structures, configurations, methods, devices and components, alternatives as to form, fit and function, and so on—may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or later developed. Those skilled in the art may readily adopt one or more of the inventive aspects, concepts or features into additional embodiments and uses within the scope of the present inventions even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the inventions may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present disclosure; however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated. Moreover, while various aspects, features, and concepts may be expressly identified herein as being inventive or forming part of an invention, such identification is not intended to be exclusive, but rather there may be inventive aspects, concepts, and features that are fully described herein without being expressly identified as such or as part of a specific invention, the scope of the inventions instead being set forth in the appended claims or the claims of related or continuing applications. Descriptions of exemplary methods or processes are not limited to inclusion of all steps as being required in all cases, nor is the order that the steps are presented to be construed as required or necessary unless expressly so stated. 
     While the invention is described herein using a limited number of embodiments, these specific embodiments are not intended to limit the scope of the invention as otherwise described and claimed herein. The precise arrangement of various elements and order of the steps of articles and methods described herein are not to be considered limiting. For instance, although the steps of the methods are described with reference to sequential series of reference signs and progression of the blocks in the figures, the method can be implemented in a particular order as desired.