Patent Publication Number: US-11391272-B2

Title: Mechanical tubular diaphragm pump having a housing with upstream and downstream check valves fixed thereto at either end of a resilient tube forming a fluid pathway wherein the tube is depressed by a depressor configured to be moved by a motorized reciprocating unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 62/349,304 filed Jun. 13, 2016, entitled “MECHANICAL TUBULAR DIAPHRAGM PUMP”, the disclosure of which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Diaphragm pumps can be useful for pumping fluids and gasses, particularly where versatility and contamination control are of concern and/or to move otherwise difficult to pump fluids. Many conventional diaphragm pumps are large and intended for permanent installation. Moreover, many conventional diaphragm pumps are not easily reconfigurable or serviceable, the conventional diaphragm discs being difficult to access and replace. These limitations can restrict the number of practical applications for diaphragm pumps. There is a need for diaphragm pumps which are portable, reconfigurable, and serviceable while maintaining high performance. 
     SUMMARY 
     Several embodiments demonstrating mechanical tubular diaphragm pump features are presented herein. A first embodiment includes a tube cyclically depressed and released by mechanical reciprocation. A pair of check valves located along the same fluid pathway as the tube limits flow of fluid to an upstream-to-downstream direction. Depression of the tube forces fluid downstream from the tube while release of the tube draws in upstream fluid. Such a pump can utilize any feature or aspect, or combination of the same, disclosed herein. 
     A second embodiment includes a resilient tube having a lumen and a pair of upstream and downstream check valves located along the same fluid pathway as the lumen. The tubular pump further includes a motorized reciprocating unit and a depressor configured to be moved by the motorized reciprocating unit to cyclically depress and release the resilient tube. The resilient tube forces fluid within the lumen downstream past the downstream check valve as the resilient tube is depressed by the depressor, and further pulls upstream fluid past the upstream check valve and into the lumen as the resilient tube returns upon release by the depressor. Multiple resilient tubes may be used in the same pump. The tube(s), depressor, and valves may be attached to a housing that is modularly removable from the motorized reciprocating unit. Such a pump can utilize any feature or aspect, or combination of the same, disclosed herein. 
     The scope of this disclosure is not limited to this summary. Further inventive aspects are presented in the drawings and elsewhere in this specification and in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a tubular diaphragm pump system. 
         FIG. 2  is a cross sectional view of the tubular diaphragm pump system of  FIG. 1 . 
         FIG. 3  is an isometric view of the modular pump of the system of  FIG. 1 . 
         FIG. 4  is a sectional view of the modular pump of the system of  FIG. 1 . 
         FIG. 5  is an isometric view of a tube and associated compressing components of the modular pump of the system of  FIG. 1 . 
         FIG. 6  is a cross sectional view of an over-under tubular diaphragm pump. 
         FIG. 7  is a schematic fluid circuit diagram of the over-under tubular diaphragm pump of  FIG. 6 . 
         FIG. 8  is a cross sectional view of a side-by side tubular diaphragm pump. 
         FIG. 9  is a schematic fluid circuit diagram of the side by side tubular diaphragm pump of  FIG. 8 . 
     
    
    
     This disclosure makes use of multiple embodiments and examples to demonstrate various inventive aspects. The presentation of the featured embodiments and examples should be understood as demonstrating a number of open-ended combinable options and not restricted embodiments. Changes can be made in form and detail to the various embodiments and features without departing from the spirit and scope of the invention. 
     DETAILED DESCRIPTION 
     Pumps of the present disclosure can be used to pump various fluids, such as liquids or gasses, including fluids containing solid matter. The pumps of the present disclosure can be used, for example, in fluid transfer, metering, and spraying applications. Various pump embodiments according to the present disclosure can include at least one resilient tube and a pair of upstream and downstream check valves integrated in a housing. The pump operates by repeatedly compressing at least one resilient tube to cause the fluid to flow through the pump and further downstream. The flow of the fluid is managed by the pair of upstream and downstream check valves. When multiple tubes are used, the tubes can be arrayed in parallel with each other. The tube(s) can be circular in cross sectional profile and linearly extend along a longitudinal dimension. Each tube can be easily replaced when the tube is worn and/or when a clean tube is desired. These and other aspects are further discussed herein. 
       FIG. 1  is a perspective view of a fluid pump system  2 . The fluid pump system  2  includes a motorized reciprocating unit  4 . The motorized reciprocating unit  4  includes an electric, gas, pneumatic, or hydraulic powered motor, each of which is well known in the art. The particular motorized reciprocating unit  4  embodiment shown in  FIG. 1  utilizes a conventional brushless direct current rotor stator, as is well known in the art, which outputs rotational motion. The motorized reciprocating unit  4  can further include a mechanism for converting rotational motion output from the motor into a linear reciprocating motion, as further discussed herein. The motorized reciprocating unit  4  is mounted on a frame  8 . The frame  8  is shown in this embodiment as a tubular structure which supports the motorized reciprocating unit  4  and the rest of the fluid pump system  2 . The frame  8  in this embodiment is shown to include legs for standing the motorized reciprocating unit  4  on the ground. The frame  8  can be formed from metal. 
     A modular pump  10  is mounted on the motorized reciprocating unit  4  by a pump coupling  6 . The pump coupling  6  securely fixes the modular pump  10  to the motorized reciprocating unit  4  while also allowing reciprocating motion output from the motorized reciprocating unit  4  to be directed into the modular pump  10 , as further discussed herein. 
     The modular pump  10  includes an inlet  12  through which fluid moves into the modular pump  10  and an outlet  14  through which the fluid moves out of the modular pump  10  under pressure. Pipes, tubes, manifolds, connectors, and the like, which are not illustrated but are known in the art, can be connected to the inlet  12  and the outlet  14  to manage fluid flow to and from the modular pump  10 . For example, a first hose can supply fluid from a reservoir to the inlet  12  while a second hose can route fluid, under pressure, from the outlet  14  to a dispensing element, such as a nozzle, or as working fluid for actuation in another motor. The inlet  12  and outlet  14  are shown to include flanges to facilitate connection with hoses, however various embodiments may not include flanges. 
     The modular pump  10  may only be attached to the motorized reciprocating unit  4  via the pump coupling  6 . In this way, the modular pump  10  may not be attached to the frame  8  or other structural element of the fluid pump system  2  except via the pump coupling  6 . This single area of attachment between the modular pump  10  and the fluid pump system  2  facilitates modular removal of the modular pump  10  from the motorized reciprocating unit  4  as further discussed herein. A cover or door may be placed over the pump coupling  6  to cover moving components, however such a cover or door is not shown in  FIG. 1 . 
       FIG. 2  is a cross sectional view of the pumping system  2 . As shown in  FIG. 2 , the modular pump  10  includes pump housing  24 . The housing  24  fully encloses, and defines, a chamber  52  inside of which pump components are located. The pump housing  24  in this embodiment appears as a rectangular box, however different housing shapes are within the scope of this disclosure, such as square and tubular housings. The pump housing  24  can be formed from metal and/or polymer. The pump housing  24  includes a cover  26  on a top side and a bottom  28  on a bottom side. The pump housing  24  further includes four sidewalls  30  connecting the bottom  28  to the cover  26 . The cover  26 , bottom  28 , and side walls  30  may be joined by fasteners (e.g., bolts) and/or welding, amongst other connecting options. Release of the fastener(s) allows the cover  26 , a side wall  30 , or the bottom  28  to be removed from the rest of the pump housing  24  (e.g., in the manner of a door) to allow access to the interior of the pump housing  24  for servicing. 
     The particular modular pump  10  shown includes a pump neck  16 . The pump neck  16  is cylindrical. The pump neck  16  extends upwards from the pump housing  24 . The pump neck  16  can be directly attached, or integral and continuous with, the pump housing  24 , such as the cover  26 .  FIG. 2  shows that the modular pump  10  can include a rib  18  or other peripheral protrusion. The rib  18  is located around the pump neck  16 . The rib  18  can be part of the pump neck  16  or otherwise be fixed with the pump neck  16 .  FIG. 2  shows that the modular pump  10  can include a retaining nut  36 . The retaining nut  36  is located around the pump neck  16 . The retaining nut  36  includes inner threading that engages outer threading on the pump neck  16 . The retaining nut  36  can be moved up and down along the pump neck  16  by rotation of the retaining nut  36  relative to the pump neck  16  due to the threading. 
     The particular modular pump  10  shown includes a drive rod  20 . The drive rod  20  includes a head  22  at its top. The head  22  facilitates attachment to the motorized reciprocating unit  4 . The drive rod  20  moves within the pump neck  16  and protrudes out from the top of the pump neck  16  to expose the head  22 . The pump neck  16  may brace the pump housing  24  relative to the motorized reciprocating unit  4  while the motorized reciprocating unit  4  moves the drive rod  20  relative to the pump neck  16  and the pump housing  24 . One or more annular guides  44  surround a portion of the drive rod  20 . The annular guides  44  can guide the drive rod  20  along a linear reciprocal path. The annular guides  44  can also seal the inside of the modular pump  10  about the reciprocating drive rod  20  to prevent escape of gas or fluid along the drive rod  20  toward the mechanics of the motorized reciprocating unit  4 . Various embodiments may not include annular guide  44 . The annular guides  44  can be formed from polymer, for example. 
     The view of  FIG. 2  shows the modular pump  10 , pump coupling  6 , and motorized reciprocating unit  4  of the fluid pump system  2 . The motorized reciprocating unit  4  generates rotational motion, as previously described, which is converted by a drive mechanism into linear reciprocal motion. The drive mechanism includes eccentric  38  and connecting arm  40  connected as a crank mechanism. The eccentric  38  is turned by a motor onboard the motorized reciprocating unit  4  behind the eccentric  38 . The top of the connecting arm  40  is connected to the eccentric  38  while the bottom of the connecting arm  40  is attached to the collar  42 . Rotation of the eccentric  38  moves the connecting arm  40  which in turn moves the collar  42  in an up-and-down linear reciprocating manner. As an alternative drive mechanism, a scotch yoke could convert rotation motion of the eccentric  38  into linear reciprocating motion of the collar  42 . The head  22  of the drive rod  20  is cradled in the slot of the collar  42  to couple the movement of the drive rod  20  with that of the collar  42 . The head  22 , and the rest of the drive rod  20 , moves up and down in a linear reciprocating manner with the movement of the collar  42 . 
     As shown in  FIGS. 1 and 2 , the neck  16  of the modular pump  10  fits within a recess of the pump coupling  6  when the modular pump  10  is mounted on the motorized reciprocating unit  4 . In the illustrated embodiment, the motorized reciprocating unit  4  includes a shelf  46 . The shelf  46  can be formed from metal and can be rigidly attached to the frame  8  and/or main structure of the motorized reciprocating unit  4 . The modular pump  10  clamps onto the shelf  46  to rigidly mount the modular pump  10  to the motorized reciprocating unit  4 . The rib  18  sits above, and rests on, the shelf  46  with the neck  16  extending below the shelf  46 . The nut  36  can be moved upwards by rotation to tighten against the bottom of the shelf  46  to clamp the shelf  46  between the nut  36  and the rib  18  to secure the modular pump  10  to the motorized reciprocating unit  4 . Such fixation prevents movement of the pump neck  16  (and the rest of the pump housing  24  and the mounts  32 ,  34 ) relative to the drive rod  20  when the drive rod  20  is reciprocated by the motorized reciprocating unit  4 . 
     The interface between the rib  18 , shelf  46 , and nut  36  (or other type of mount connection) forms a static connection. When the static connection is made, the pump neck  16 , as well as the rest of the housing  24  and the mounts  32 ,  34  of the modular pump  10 , will not move relative to the motorized reciprocating unit  4 , despite the collar  42  moving the drive rod  20  of the modular pump  10 . The interface of the drive rod  20  with the collar  42  forms a dynamic connection whereby the drive rod  20  and the collar  42  move together. 
     The modular pump  10  may be loosened by moving the nut  36  downwards by rotation to back the nut  36  off of the bottom of the shelf  46 . Once loosened, the modular pump  10  can be dismounted from the motorized reciprocating unit  4  by sliding the modular pump  10  forward, in a single motion, away from the motorized reciprocating unit  4 . The sliding motion removes the pump neck  16  from the motorized reciprocating unit  4  and also removes the head  22  of the drive rod  20  from the slot of the collar  42 . This single sliding motion simultaneously disengages both the static and dynamic connections, assuming any clamps are loosened. It is noted that the illustrated mechanical components forming the pump coupling  6  demonstrate one example of mechanical components which can form static and dynamic mechanical connections which are easily breakable, and that different components having the same function are within the scope of this disclosure. 
     The dismounting of the modular pump  10  allows the modular pump  10  to be cleaned and serviced. Alternatively, the modular pump  10  can be removed for replacement by a newer, cleaner, or alternatively configured modular pump  10  (e.g., a larger, smaller, or adapted for different fluids, pressures, viscosities, and/or chemical resistances). 
     After servicing and/or modification, the modular pump  10  (or a different modular pump) can be remounted on the motorized reciprocating unit  4 . The modular pump  10  is slid in a single linear motion to simultaneously engage (or reengage) the static and dynamic connections. The modular pump  10  is slid so that the rib  18  is above the shelf  46  and the nut  36  is below the shelf  46 . Simultaneously, the head  22  is slid into the slot of the collar  42 . After sliding, the nut  36  is moved upward and tightened against the shelf  46  to secure the modular pump  10  to the motorized reciprocating unit  4 . 
     The mechanics of the modular pump  10  will be further discussed herein in reference to  FIGS. 2-5 .  FIG. 3  is an isometric view of the modular pump  10  in isolation. In this view, the modular pump  10  has been removed from the motorized reciprocating unit  4  by disengagement at the pump coupling  6  as previously described.  FIG. 4  shows a sectional view of the modular pump  10 .  FIG. 5  shows the pump  10  without the pump housing  24 . 
     Within the housing  24  is a chamber  52 . The chamber  52  is typically filled with air and open to the atmosphere via one or more holes through the housing  24 . Entirely within the chamber  52  of the housing  24  is a tube  50 . The tube  50  has a lumen  54  and defines part of a fluid pathway that extends from the inlet port  12  to the outlet port  14 . The tube  50  is mounted an upstream mount  32  and a downstream mount  34 . 
     The tube  50  extends straight between the mounts  32 ,  34  without bending in a nominal (i.e. undepressed) state. In this way, the tube  50  has a straight profile. The tube  50  has a circular cross section in its nominal state. Specifically, along its length, the tube  50  has a circular inner diameter and outer diameter. While tube  50  has a circular cross sectional profile in its nominal state as shown, the tube  50  may take a different nominal shape, such as elliptical or square. The tube  50  is resilient such that the tube  50  resists deformation by mechanical compression (but still collapses), and after release of the mechanical compression the tube  50  intrinsically returns to its nominal shape due to the spring properties of the material forming the tube  50 . The tube  50  can be formed from various polymers, such as PTFE, silicone, or rubber, amongst other options. 
     The tube  50  has opposite upstream and downstream ends mounted on ends of an upstream mount  32  and a downstream mount  34 , respectively. In the embodiment shown, the downstream end of the upstream mount  32  includes a narrowed circular end over and around which the upstream end of the tube  50  fits to seal the upstream end of the tube  50  with the upstream mount  32 . Also, the upstream end of the downstream mount  34  includes a narrowed circular end over and around which the downstream end of the tube  50  fits to seal the downstream end of the tube  50  with the downstream mount  34 . In other words, respective ends of the mounts  32 ,  34  are received within opposite ends of the tube  50 . Alternatively, the opposite ends of the tube  50  could be received in larger diameter ends of the mounts  32 ,  34 . No fluid is leaked into the pump housing  24  from the tube  50  or elsewhere. 
     The modular pump  10  is shown to include an upstream mount  32  and a downstream mount  34 . The upstream mount  32  defines the inlet port  12  and the downstream mount  34  defines the outlet port  14 , however the ports  12 ,  14  may be defined by different structures in various alternative embodiments. The mounts  32 ,  34  can extend through apertures formed in opposite side walls  30 . The mounts  32 ,  34  can be attached to the side walls  30 . As shown, the mounts  32 ,  34  are attached to opposite sides of the side walls  30  and project from the housing  24  in opposite directions. One or both mounts  32 ,  34  may have exterior threading that interfaces with interior threading in the apertures of the side walls  30  through which the mounts  32 ,  34  extend. The threaded interface(s) can allow the position of the mounts  32 ,  34  (along a horizontal left-right axis) to be changed relative to the rest of the housing  24  by relative rotation resulting in moving further inward or outward from the chamber  52 . Moreover, rotation of one or both of the mounts  32 ,  34  relative to the housing  24  changes the spacing between the inner, opposed ends on the mounts  32 ,  34  on which the ends of the tube  50  are mounted. Adjusting the spacing in this way can help appropriately position the tube  50  as well as accommodate shorter and longer tubes. The mounts  32 ,  34  may alternatively be welded to the side walls  30  and therefore fixed. In another embodiment, the mounts  32 ,  34  are formed from the same material as, and are contiguous with, the side walls  30 . The mounts  32 ,  34  can be formed from metal and/or polymer. 
     Fastener bands  66  are wrapped around the ends of the tube  50 , over the upstream and downstream mounts  32 ,  34 , respectively, to secure the tube  50  and seal the interior of the tube  50  to create a no-loss fluid pathway between the inlet  12  and the outlet  14 . A portion of the upstream end of the tube  50  is positioned over a portion of the upstream mount  32  and a band fastener  66  is located around the portion of the upstream end of the tube  50  to squeeze and seal the portion of the upstream end of the tube  50  against the portion of the upstream mount  32 . A portion of the downstream end of the tube  50  is positioned over a portion of the downstream mount  34  and another band fastener  66  is located around the portion of the downstream end of the tube  50  to squeeze and seal the portion of the downstream end of the tube  50  against the portion of the downstream mount  34 . The fastener bands  66  may be tightened or loosened, such as by a screw driver, the fastener bands  66  being loosened to allow remove of the ends of the tube  50  from over the inner, opposing ends of the upstream and downstream mounts  32 ,  34 . 
     The flow of fluid through the lumen  54  of the tube  50  is managed by valves  62 ,  64  located upstream and downstream, respectively, about the tube  50 . Valve  62  is a check valve which allows fluid to flow from inlet port  12  into the lumen  54  but not in the reverse direction. Valve  65  is also a check valve which allows fluid to flow from within the lumen  54  through the outlet port  14 , but not in the reverse direction. Together, the valves  62 ,  64  manage flow only in an upstream-to-downstream direction, which in the orientation of the view of  FIG. 2  is right-to-left from the inlet  12  to the outlet  14 , by preventing retrograde downstream-to-upstream flow. In this manner, the fluid passes through the inlet valve  62 , through the upstream mount  52 , through the lumen  54  within the tube  50 , through the downstream mount  53 , and past the outlet valve  64 . 
     In the illustrated embodiment, each of the valves  62 ,  64  includes (in order from right-to-left) a seat, a ball, a cage, and a spring. The spring keeps the ball against the seat unless the spring force is overcome from the upstream direction, in which case the valve opens to allow flow only in the downstream direction. The valves  62 ,  64  are shown as ball valves, although different types of check valves can be used instead, such as flapper and poppet valves. 
     The inlet valve  62  is housed within the upstream mount  32 . Likewise, the outlet valve  64  is housed within the downstream mount  34 . In some embodiments, the valves  62 ,  64  may not be housed in the mounts  32 ,  34 , and instead can be in located within separate housings that respectively support the check valves along the same fluid pathway. The valves  62 ,  64  are shown as located outside of the interior of the housing  24 . Further, the valves  62 ,  64  are accessible from the ends of the mounts  32 ,  34  for servicing without opening the housing  24  or otherwise disassembling other parts of the modular pump  10 . Alternatively, the valves  62 ,  64  could be located within the housing  24 . In some embodiments, the valves  62 ,  64  may be located within the respective upstream and downstream ends of the tube  50 , the valves  62 ,  64  housed within the portions of the mounts  32 ,  34  that extend within the upstream and downstream ends of the tube  50 . 
     As shown in  FIGS. 2 and 4-5 , a depressor  56 , a tube  50 , and a stop  58  are located within the chamber  52  of the housing  24 . The depressor  56 , the tube  50 , and the stop  58  are entirely contained and located within the chamber  52  of the housing  24 . The tube  50  is directly between (i.e. sandwiched by) the depressor  56  and the stop  58 . Each of the depressor  56  and the stop  58  extend into the chamber  52  and are separate from the housing  24 . For example, the depressor  56  is located below, and separated from, the cover  24 . The stop  58  is located above, and separated from, the bottom  28 . 
     The depressor  56  is fixed to the drive rod  20  by fastener  48 , although the relative distance between the depressor  56  and the drive rod  20  can be adjusted (to a plurality of different relative positions) as further discussed herein. Being fixed to the drive rod  20 , the depressor  56  is reciprocated along upstrokes and downstrokes with the drive rod  20  as the drive rod  20  is reciprocated by the motorized reciprocating unit  4 . The stop  58  is mounted to the housing  24  and remains stationary during reciprocation of the depressor  56 . The position of the stop  58  is also adjustable (e.g., upwards and downwards) to a plurality of different positions, as will be explained further herein. 
     The downward motion of the depressor  56  on the downstroke squeezes the tube  50  directly between the depressor  56  and the stop  58  to cause the tube  50  to partially collapse or in some manner change in dimension to reduce the volume within the lumen  54 . Because the tube  50  is sealed with each of the mounts  32 ,  34 , a decrease in the inner volume of the lumen  54  increases the pressure within the lumen  54  and forces fluid within the lumen  54  to flow downstream past the outlet valve  64  while the inlet valve  62  closes to resist the fluid within the lumen  54  from flowing in the upstream direction. When the downstroke of the depressor  56  is complete and the depressor  56  moves upwards in an upstroke, the resiliency of the tube  50  causes the tube  50  to form its original shape (e.g., the tubular shape depicted). The recovery of the tube  50  causes the lumen  54  to expand in volume, thereby lowering the pressure within the lumen  54 . The outlet valve  64  closes in response to this reversal in flow to prevent downstream fluid from reentering the tube  50 . Meanwhile, the suction effect of the recovery of the tube  50  opens the inlet valve  62  and pulls upstream fluid past the inlet valve  62  and into the lumen  60 . The depressor  56  finishes the upstroke and begins the next downstroke, starting the reciprocation cycle over again as the tube  50  is depressed, the valves  62 ,  64  reverse their states, and the fluid drawn into the lumen  54  on the previous upstroke is expelled downstream on the downstroke. This reciprocation cycle can be performed at relatively high frequency, such as, for example, between 1 Hz. and 100 Hz, although other frequencies, lesser and greater, are possible. 
     It is noted that neither the depressor  56  nor other structure urges the tube  50  to spring back to its nominal shape. Rather, the resilient material properties of the tube  50  itself causes the tube  50  to reform its nominal shape upon release by the depressor  56 . Therefore, it is the tube  50  retaking its nominal shape that expands the lumen  54  and draws upstream fluid past the valve  62  and into the lumen  54 . 
     The depressor  56  can be formed from metal or polymer. The depressor  56  can be a plate. The depressor  56  can be a disc. The depressor  56  can be wider or narrower than what is shown in the illustrated embodiment to correspondingly increase or decrease the length of the tube  50  depressed as well as the volume of the lumen  54  that is changed in each reciprocation cycle. The depressor  56  is fixed to the drive rod  20  via fastener  48 . In the illustrated embodiment, the fastener  48  is a threaded rod that extends through, and is attached to (e.g., via welding or threading), a central aperture within the depressor  56 . The fastener  48  extends into, and threadedly engages with, a threaded hole on the bottom of the drive rod  20 . The threading interface fixes the position of the depressor  56  with respect to the drive rod  20  during pumping but allows for adjustment in their relative positions during servicing. 
     The position of the depressor  56  can be changed relative to the position of the drive rod  20 . For example, in the illustrated embodiment, the depressor  56  is threadedly attached to the drive rod  20  such that relative rotation moves the depressor  56  up or down (closer or farther away) from drive rod  20 , depending on the direction of rotation. Other adjustable means of attachment between the depressor  56  and drive rod  20  are possible, such as indexing of overlapping holes through which a pin can be inserted. The depressor  56  can change its position relative to the drive rod  20  to change the locations of the depressor  56  at which it reaches the top of the upstroke and the bottom of the downstroke. Lowering or raising the location of the bottom of the downstroke increases or decreases, respectively, the depth of compression of the tube  50  during reciprocation cycles, thereby adjusting the change in volume of the lumen  54  in each reciprocation cycle. Greater depth of compression can result in pumping a greater volume, but typically with greater motor load. 
     It may be preferable to close or distance the relative vertical positions of the depressor  56  and the drive rod  20  so that the location of the depressor  56  at the top of the upstroke is high enough such that the depressor  56 , for at least a brief moment during the reciprocation cycle, no longer applies a force on the tube  50  to allow the tube  50  to be fully released. However, it may also be preferable to adjust the relative positions of the depressor  56  and the drive rod  20  so that no large gap, or possibly not any gap, is formed between the tube  50  and the depressor  50  during the upstroke (or other part of the reciprocation cycle) so that the entire downstroke is used for compressing the tube  50  without any unnecessary travel to reengage the tube  50 . Adjusting the relative positions of the depressor  56  and the drive rod  20  allows the user to adjust the degree to which the tube  50  is released on the upstroke. In some cases, the depressor  56  fully releases the tube  50  so that the tube  50  is allowed to spring back to its nominal shape. In some cases, the depressor  56  only moves upwards on the upstroke enough to partially releases the tube  50  so that the tube  50  is not allowed to spring back to its nominal shape, although the tube  50  is still released to expand to some degree relative to the shape of the tube  50  at the bottom of the downstroke. 
     The stop  58  can be formed from metal or polymer. The stop  58  can be a plate. The stop  58  can be a disc. In the illustrated embodiments, the depressor  56  and the stop  58  are coaxially aligned discs. The stop  58  can be wider or narrower than what is shown in the illustrated embodiment to correspondingly increase or decrease the length of tube  50  compressed as well as the volume of the lumen  54  that is changed in each reciprocation cycle. The stop  58  is attached to a support  60 . The support  60  can be a rod having exterior threading that engages inner threading of the aperture of the pump housing  24  (e.g., in the bottom  28 ) through which the support  60  extends. Rotation of the support  60  (e.g., from outside the pump housing  24 ) changes the position of the stop  58  relative to the position the pump housing  24  and the tube  50  to control the depth of compression of the tube  50  during the reciprocation cycle as well as adjusting any preload on the tube  50 . Other adjustable means of attachment between the stop  58  and support  60  are possible, such as indexing of overlapping holes through which a pin can be inserted. 
     The stop  58  can change its position relative to the support  60  to increase or decrease the depth of compression of the tube  50  during reciprocation cycles, thereby adjusting the change in volume of the lumen  54  per reciprocation cycle. For example, the stop  58  may be positioned to contact the tube  50  at all times but apply a reaction force on the tube  50  only when the depressor  56  is pushing on the tube  50 . Such an arrangement does not preload the tube  50  and maximizes the change in volume in the lumen  54  during the reciprocation cycle. The stop  58  may be positioned to depress the tube  50  even when the depressor  56  is at the top of its upstroke, such that the tube  50  is preloaded. Such an arrangement may be useful to prevent travel of the tube  50  during or between reciprocation cycles. In another example, the stop  58  may be positioned to not contact the tube  50  except for when the depressor  56  is pushing the tube  50  toward the stop  58  (e.g., when the depressor  56  is on the downstroke). Such an arrangement may be useful to decrease the amount of volumetric change in the lumen  52  during the reciprocation cycle, prevent any distortion of the tube  50  except during a reciprocation cycle, and/or to ensure that the tube  50  is free to spring back to its nominal state between reciprocation cycles. 
     Utilizing one or both of the modular pump  10  dismounting feature and the housing  24  opening feature, the performance of the fluid pump system  2  may be changed just by changing the tube  50 . The tube  50  can be replaced by removal of the fastener bands  66  (e.g., by loosening with a screw driver) and removing the upstream and downstream ends of the tube  50  from the inner, opposing ends of the mountings  32 ,  34 . A new tube  50 , possibly having different dimensions and/or material properties, can be remounted on the inner, opposing ends of the mountings  32 ,  34  and the fastener bands  66  tightened around the ends of the new tube  50 . As an example, a first type of tube  50  made from a first type of material having particular properties and having a first set of dimensions (e.g., inner diameter and wall thickness) may be suited for a first fluid transfer project. After the first fluid transfer project is complete, the modular pump  10  can be dismounted and/or the housing opened  24  and the tube  50  replaced with a second type of tube  50  made from a second type of material having particular properties and having a second set of dimensions suited for a second fluid transfer project, the first and second types of materials and dimensions being different from one another. In this way, the mere replacement of the tube  50  allows the pumping performance characteristics of the fluid pump system  2  to be easily changed depending on the demands of the particular task, thereby expanding the versatility of the fluid pump system  2  by the mere substitution of tubes  50 . 
     The view of  FIGS. 2, 4-5  show a single tube being used, however more than one tube may be used at a time.  FIGS. 6-9  demonstrate various multi-tube embodiments. The tube arrangements shown in  FIGS. 6-9  can be implemented in the modular pump  10 , with all of the tubes fitting within the housing  24 , and further used with the motorized reciprocating unit  4  as in the pump system  2 . The mounts  32 ,  34  can have multiple fluid pathways, such as in the manner of a manifold, as well as multiple check valves, as demonstrated in the following FIGS. The pump components of  FIGS. 6-9  can replace the correspondingly numbered internal pump components of the previously illustrated embodiment. 
       FIG. 6  shows a cross sectional view of tubes  150 A-B in an over/under arrangement, the tubes  150 A-B extending parallel with one another. It is noted that components sharing the first two digits of a reference numbers (e.g.,  50 ,  150 ,  250 ;  56 ,  156 ,  256 , etc.) of different embodiments can have similar configurations amongst the various illustrated and described embodiments, except for those aspects specifically shown or described to be different. For example, the drive rod  120  can be identical in form and/or function to drive rod  20 , and can be used in a similar fluid pump system  2 , except for those particular aspects shown or described to be different. For the sake of brevity, the description of common aspects (e.g., overall fluid pump system, materials, features, functions, properties, etc.) are not repeated for different components having similar reference numbers. For all referenced embodiments, an aspect described and/or shown for one embodiment can be implemented in another embodiment unless otherwise described or shown to be incompatible. In some cases, only the differences between the embodiments are described. 
     The pump of the embodiment of  FIG. 6  includes a drive rod  120  connected to a depressor  156 . The drive rod  120  is connected to a mechanism that, similar to the reciprocation mechanism of the previous embodiment (e.g., the motorized reciprocating unit  4 ), moves the drive rod  120  linearly up and down. The depressor  156  is attached to the drive rod  120  and moves up and down through up and down strokes with the drive rod  120 . The depressor  156  is located directly between (i.e. sandwiched) tubes  150 A-B, which are further located directly between cover  126  and stop  158 . The cover  126  could instead be a stop. The stop  158  could instead be a bottom of a housing (such as bottom  28  of housing  24 ). In any case, the cover  126  and stop  158 , or other surfaces which support the tubes  150 A-B, do not move during pumping and instead brace the tubes  150 A-B while the depressor  156  moves. The cover  126 , stop  158 , and depressor  156 , and/or other tube contacting elements can be positionally adjustable in the same manner as the depressor  56  and stop  58  are positionally adjustable in the previous embodiment. The cover  126  and stop  158  form grooves  172  within which the tubes  150 A-B reside to prevent the tubes  150 A-B from moving laterally when compressed. 
     The pump of  FIG. 6  is double acting in that, on the downstroke, tube  150 B is compressed to force fluid from lumen  154 A downstream while tube  150 A is allowed to recover to pull upstream fluid into lumen  154 B. This is reversed on the upstroke when the tube  150 B is allowed to recover while tube  150 A is compressed. This increases the output of the pump and reduces pressure and flow spikes in the fluid output by the pump as fluid is sucked in and expelled from the tubes  150 A-B on each of the upstroke and downstroke. The embodiment of  FIGS. 6-7  can be used in the fluid pump system  2 , and the tubes  150 A-B can replace the single tube  50  in the housing  24 . 
       FIG. 7  is a schematic flow diagram demonstrating an option for arranging the tubes  150 A-B of the embodiment of  FIG. 6  relative to check valves  162 A-B,  164 A-B. The check valves  162 A-B,  164 A-B may be similar to check valves  62 ,  64  in configuration and orientation and by being housed on the modular pump  10  (e.g., in mountings). For example, the check valves  162 A-B,  164 A-B only allow fluid to flow in an upstream-to-downstream direction as the tubes  150 A-B are depressed and released. 
       FIG. 7  demonstrates that, after passing through the fluid inlet  112 , the flow of fluid can be divided into two parallel flow paths (or some other number equal to the number of tubes used) before passing through a corresponding number of inlet valves  162 A-B (or some other number equal to the number of tubes used), a corresponding number of tubes  150 A-B, and a corresponding number of outlet valves  146 A-B, and then being rejoined before passing through fluid output  114 . As with the previous embodiment, the flow is between fluid inlet  112  and fluid output  114 . As such, the inlet valves  162 A-B, the tubes  150 A-B, lumens  154 A-B, and outlet valves  146 A-B, are respectively located along parallel fluid pathways. 
       FIG. 8  shows a cross sectional view of tubes  250 A-C in a side-by-side arrangement, the tubes  250 A-C extending parallel with each other.  FIG. 9  is a schematic flow diagram demonstrating an option for arranging the tubes  250 A-C of the embodiment of  FIG. 8  relative to check valves  262 A-C,  264 A-C. The pump components of  FIGS. 8-9  can replace the corresponding internal pump components of the previous embodiments. For example, the embodiment of  FIGS. 8-9  can be used in the fluid pump system  2 , and the tubes  250 A-C can replace the single tube  50  in the housing  24 . The embodiment of  FIGS. 8-9  includes a drive rod  220  connected to a depressor  256 . The drive rod  220  is connected to a mechanism that, similar to the reciprocation mechanism of the previous embodiments, moves the drive rod  220  linearly up and down respectively corresponding to up and down strokes. 
     Three tubes  250 A-C are located directly between (i.e. sandwiched between) the depressor  256  and the stop  258 . The stop  258  can be similar to the stop  58  of the first embodiment, such as by being adjustable by support  60 . The stop  258  may alternatively be the bottom  28  of the housing  24 . While three tubes are shown, any number of tubes can be used, such as 1, 2, 4, or a greater number. The tubes  250 A-C are simultaneously depressed by the depressor  256  during the downstroke to expel fluid out of the lumens  254 A-C and simultaneously released on the upstroke to recover and pull in more fluid through a fluid inlet  212  and into the lumens  254 A-C. The embodiment of  FIGS. 8-9  demonstrates, among other things, that a single depressor  256  can simultaneously squeeze multiple tubes to increase the fluid output of a pump and release multiple tubes to correspondingly increase fluid intake into the pump. A groove can be formed in either of both of the depressor  256  and the stop  258 , the tubes  250 A-C residing in the groove to prevent lateral movement of the tubes  250 A-C during pumping. 
       FIG. 9  demonstrates that the flow of fluid can be divided between the three tubes  250 A-C (or some other number of tubes) after passing through inlet valve  262  and rejoined before passing through outlet valve  264 . Check valves  262 ,  264  may be similar to check valves  62 ,  64  in configuration and orientation and by being housed on the modular pump  10  (e.g., in mountings). For example, the check valves  262 ,  264  only allow fluid to flow in an upstream-to-downstream direction as the tubes  250 A-C are depressed and released. The mounts on which the tubes  250 A-C are mounted may be similar to the mounts  32 ,  34  except that the mountings of this embodiment divide the flow path upstream and then consolidate the flow paths downstream instead of having a single flow path as with the first embodiment.  FIG. 9  demonstrates that, after passing through the fluid inlet  212 , the flow of fluid can pass through inlet check valve  212  before being divided into three parallel flow paths (or some other number equal to the number of tubes used) through the tubes  250 A-B. The fluid is pulled through the inlet  212  and inlet check valve  262  and then into each of the tubes  250 A-B as the tubes  250 A-C recover during decompression on the upstroke. The fluid is expelled from the tubes  250 A-B as the tubes  250 A-C are depressed by depressor  256  on the downstroke. Specifically, the fluid is expelled through outlet check valve  264  and outlet port  214 . 
     Although “top” and “bottom”, “up” and “down”, “left” and “right”, and “upstream” and “downstream” are used herein for convenience to correspond to the orientations shown, these and other embodiment need not have such orientation. For example, for parts having “top” (cover) and “bottom” designations herein, “first” and “second” designations can alternatively be used. Likewise, for parts having “upstream” and “downstream” designations herein, “first” and “second” designations can alternatively be used. The “downstroke” of a depressor (or other component) can be referred to as movement of a depressor in a first direction, while the “upstroke” of a depressor (or other component) can be referred to as movement of a depressor in a second direction opposite the first direction. 
     The present disclosure is made using different embodiments to highlight various inventive aspects. As such, the disclosure presents the inventive aspects in an exemplar fashion and not in a limiting fashion. Modifications can be made to the embodiments presented herein without departing from the scope of the invention. For example, a feature disclosed in connection with one embodiment can be integrated into a different embodiment. As such, the scope of the invention is not limited to the embodiments disclosed herein.