Patent Publication Number: US-2003226857-A1

Title: Systems for forming sterile fluid connections and methods of use

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims priority to U.S. Provisional patent application Ser. No. 60/372,162, filed Apr. 12, 2002, which application is incorporated herein by specific reference. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. The Field of the Invention  
       [0003] The present invention relates to systems for forming sterile fluid connections and methods for using such systems.  
       [0004] 2. The Relevant Technology  
       [0005] Culture media, buffers, reagents and other biological materials (hereinafter “base materials”) are used extensively by biotech companies in research and development, creating vaccines, producing and purifying proteins, and developing other biologicals. To be safe and effective for their intended use, these base materials must be pure and sterile. As such, base materials are typically made by specialized manufacturers or end-users that have made large investments in sophisticated equipment and facilities. Such equipment and facilities are operated under highly controlled procedures that are regulated by the Food and Drug Administration (FDA) and other related agencies.  
       [0006] For example, most of the base materials are hydrated in large stainless steel tanks where purified water is combined with a precise amount of a desired base material in its powdered form. Some supplements may be added in liquid form as well. A special mixer is then used to mix the components into the desired end solution. Once the solution is prepared, the solution is filtered and may be directly used or dispensed and sealed into sterile containers for shipment or storage. The entire system is typically operated in some form of clean room.  
       [0007] Between the production of different batches of materials, the mixing tanks, mixers, and all other reusable components that contact the solution must be carefully cleaned to avoid any cross contamination. The cleaning of the structural components is labor intensive, time consuming, and costly. For example, depending on the structural component and the material being produced, cleaning can require the use of chemical cleaners such as sodium hydroxide and may require steam sterilization as well. The use of chemical cleaners has the additional challenge of being relatively dangerous to use and cleaning agents can be difficult and/or expensive to dispose of once used.  
       [0008] Due to the huge expense in creating, operating, and maintaining the elaborate systems used in the manufacture of base materials, biotech companies frequently purchase the base materials in their final solution form. There are, however, certain drawbacks to this strategy. For example, the base materials in the solution form are primarily water. As such, these materials can be difficult and expensive to transport.  
       [0009] Furthermore, although the powdered base materials can be stored for an extended period of time under relatively ambient conditions, the final liquid solutions must typically be stored under refrigerated conditions and have a significantly shorter shelf life. Due to the required refrigeration, storage of significant amounts of the base materials in their solution form can be expensive.  
       [0010] Accordingly, what is needed are systems and components of such systems that enable an end user to hydrate its own base materials into solution form based on its immediate needs but which do not require the highly regulated and labor intensive cleaning and sterilization processes used by typical manufactures. Such systems would enable the end user to minimize the storage of large amounts of base material in solution form while enabling it to maximize the use of powdered base materials which are more efficient to transport and store. Manufacturers could also use such systems to simplify their manufacturing processes.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011] Various embodiments of the present invention will now be discussed with reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope.  
     [0012]FIG. 1 is an elevated front view of one embodiment of a fluid preparation system;  
     [0013]FIG. 2 is a cross sectional top view of the tank assembly taken along section lines  2 - 2  of FIG. 1;  
     [0014]FIG. 2A is an enlarged section view of the tank assembly shown in FIG. 2A;  
     [0015]FIG. 3 is a partially cut away side view of the side wall of the tank assembly shown in FIG. 1 illustrating fluid channels therein;  
     [0016]FIG. 4 is a cross sectional side view of the tank assembly taken along section lines  4 - 4  of FIG. 2;  
     [0017]FIG. 5A is a cross sectional side view of the tank assembly taken along section lines  5 - 5  of FIG. 2;  
     [0018]FIG. 5B is the same cross sectional side view shown in FIG. 5A with the floor therein being raised;  
     [0019]FIG. 6 is an elevated front view of an alternative embodiment of a tank assembly;  
     [0020]FIG. 7 is a top plan view of the tank assembly shown in FIG. 6;  
     [0021]FIG. 8 is an exploded partial perspective view of a mixing bag assembly;  
     [0022]FIG. 9 is an elevated side view of a panel of the mixing bag shown in FIG. 8;  
     [0023]FIG. 10A is a cross sectional side view of the top end of the mixing bag shown in FIG. 8;  
     [0024]FIG. 10B is a cross sectional side view of an alternative embodiment of the top end of the mixing bag shown in FIG. 8;  
     [0025]FIG. 11 is a cross sectional side view of the bottom end of the mixing bag shown in FIG. 8 with a mixer disposed therein;  
     [0026]FIG. 12 is a top plan view of the mixer shown in FIG. 11;  
     [0027]FIG. 13A is a bottom perspective view of the mixer shown in FIG. 11;  
     [0028]FIG. 13B is a bottom perspective view of the mixer shown in FIG. 13A with the flaps thereof being downwardly flexed;  
     [0029]FIG. 14A is a cross sectional side view of the bottom end of the mixing bag shown in FIG. 8 with an alternative embodiment of a mixer disposed therein;  
     [0030]FIG. 14B is a cross sectional side view of the mixer shown in FIG. 14A in a second position;  
     [0031]FIG. 15 is a top plan view of the mixer shown in FIG. 14A;  
     [0032]FIG. 16 is a bottom perspective view of the mixer shown in FIG. 14A with the flaps thereof being downwardly flexed;  
     [0033]FIG. 17 is an enlarged cross sectional side view of the hub of the mixer shown in FIG. 14A;  
     [0034]FIG. 18A is a cross sectional side view of the bottom end of the mixing bag shown in FIG. 8 with an alternative embodiment of a mixer disposed therein;  
     [0035]FIG. 18B is a cross sectional side view of the mixer shown in FIG. 18A in a second position;  
     [0036]FIG. 19 is a top plan view of the mixing bag shown in FIG. 8 in a collapsed state bounded by a harness;  
     [0037]FIG. 20 is an elevated side view of a feed bag coupled with the top end of the mixing bag shown in FIG. 8;  
     [0038]FIG. 21A is a top plan view of a regulator in an open position operable with the feed bag shown in FIG. 20;  
     [0039]FIG. 21B is a top plan view of the regulator shown in FIG. 21A in a closed position;  
     [0040]FIG. 22 is an elevated side view of an alternative embodiment of the feed bag shown in FIG. 20;  
     [0041]FIG. 23 is a perspective view of a port of the feed bag shown in FIG. 22;  
     [0042]FIG. 24 is an elevated side view of a spray nozzle disposed within a port of the mixing bag shown in FIG. 8;  
     [0043]FIG. 25 is an elevated side view of the spray nozzle shown in FIG. 24;  
     [0044]FIG. 26 is a cross sectional side view of the spray nozzle shown in FIG. 25;  
     [0045]FIG. 27 is a perspective view of a temperature probe;  
     [0046]FIG. 28 is a partial cross sectional side view of the temperature probe shown FIG. 27;  
     [0047]FIG. 29 is a top plan view of the sensor of the temperature probe shown in FIG. 28;  
     [0048]FIG. 30 is a partial cross sectional side view of the temperature probe shown FIG. 27 mounted to the floor of the tank assembly shown in FIG. 1;  
     [0049]FIG. 31 is a schematic illustration of the filter assembly of the fluid preparation system shown in FIG. 1;  
     [0050]FIG. 32 is an exploded perspective view of a pressure sensor assembly used in association with the filtration system shown in FIG. 31;  
     [0051]FIG. 33 is a cross sectional side view of the pressure sensor assembly shown in FIG. 32 in an assembled state;  
     [0052]FIG. 34 is an elevated side view of an alternative embodiment of a diaphragm of the pressure sensor assembly shown in FIG. 32;  
     [0053]FIG. 35 is an elevated side view of an alternative embodiment of the diaphragm shown in FIG. 34;  
     [0054]FIG. 36 is an elevated side view of a delivery assembly and a collector assembly operable with a sterilizer;  
     [0055]FIG. 37 is a cross sectional side view of a fill tube of the delivery assembly shown in FIG. 36;  
     [0056]FIG. 38 is an end view of the fill tube shown in FIG. 37;  
     [0057]FIG. 39 is a cross sectional side view of a cap on the fill tube shown in FIG. 37;  
     [0058]FIG. 40 is a cross sectional side view of a fill port of the collector assembly shown in FIG. 36;  
     [0059]FIG. 41 is a perspective view of a pair of adjacent sterilizers;  
     [0060]FIG. 42 is a enlarged perspective view of the internal components of the sterilizer shown in FIG. 41;  
     [0061]FIG. 43 is a partially cut away perspective view of the sterilizer shown in FIG. 42;  
     [0062]FIG. 44 is a cross sectional side view of a cap remover;  
     [0063]FIG. 45 is a perspective view of the sterilizer of FIG. 43 with the shuttles thereof moved into the housing;  
     [0064]FIG. 46 is a cross sectional side view of the fill tube of FIG. 37 disposed with the sterilizer in vertical alignment with the cap remover;  
     [0065]FIG. 47 is a cross sectional side view of the assembly shown in FIG. 46 with the cap of the fill tube being mated with the cap remover;  
     [0066]FIG. 48 is a cross sectional side view of the assembly shown in FIG. 47 with the cap being removed from the fill tube;  
     [0067]FIG. 49 is a perspective view of the sterilizer shown in FIG. 42 with the fill port being coupled therewith;  
     [0068]FIG. 50 is a cross sectional side view of the fill tube shown in FIG. 48 being aligned with the fill port; and  
     [0069]FIG. 51 is a cross sectional side view of the fill tube shown in FIG. 48 coupled with the fill port.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0070] Depicted in FIG. 1 is one embodiment of a fluid preparation system  10  incorporating features of the present invention. Fluid preparation system  10  is used for mixing two or more components, at least one of the components being liquid, so as to produce a homogeneous solution. Although each of the components can be liquid, in one typical embodiment one component is a substantially dry material such a powder, grain, granule or other form of solid while the other component is a liquid such as water. Fluid preparation system  10  can be used in producing any form of solution including those which are sterile and those which are non-sterile. In one common embodiment, fluid preparation system  10  is used in the manufacture of culture media, buffers, reagents and other biological materials that may or may not be sterile.  
     [0071] In one embodiment fluid preparation system  10  is designed so that structural components of the system that are directly in contact with the solution are disposable. Accordingly, as fluid preparation system  10  is shifted between the manufacture of different batches or types of solutions, the contaminated components are simply replaced with new components. Depending on the component and the intended solution, the new component can be sterile or non-sterile. As a result, multiple different solutions can be manufactured relatively quickly without the down time and added expense of sterilization or cleaning of the system. In other embodiments, however, select or all of the components of the system can be designed for sterilization and reuse.  
     [0072] In general, though not required or exclusive, fluid preparation system  10  comprises a tank assembly  20  mounted on a platform  12 , a mixing assembly  200  at least partially disposed within tank assembly  20 , a filtration system  500  in fluid communication with mixing assembly  200 , and a dispensing system  700  in fluid communication with filtration system  500 .  
     [0073] In the embodiment depicted in FIG. 1, fluid preparation system  10  includes movable platform  12  on which all or some of the components of fluid preparation system  10  are mounted. If desired, some or all of the system components can be mounted on platform  12  at a manufacturing facility prior to shipping and final assembly at an end user location. Fluid preparation system  10  can thus be formed as a modular unit that is relatively easily moved between different facilities. Alternatively, the various components can be mounted on and/or about platform  12  at the end user location. In another embodiment, it is appreciated that platform  12  is not required and that fluid preparation system  10  can be permanently or otherwise assembled at an end user facility.  
     [0074] I. Tank Assembly.  
     [0075] A. Side Wall.  
     [0076] Tank assembly  20  comprises a plurality of legs  22  upstanding from platform  12  and supporting an annular side wall  24 . As shown in FIGS. 1 and 2, side wall  24  has an interior surface  26  and an exterior surface  28  each extending between an upper end  30  and an opposing lower end  32 . Interior surface  26  at least partially bounds a chamber  60 . Side wall  24  has a tubular configuration so that upper end  30  and lower end  32  are open.  
     [0077] Side wall  24  comprises a body portion  23  having a substantially C-shaped transverse cross section. Body portion  23  terminates at substantially opposingly facing end plates  54  and  56  with a doorway  57  formed therebetween. Although not required, to increase the hoop strength of body portion  23 , a support brace  58  rigidly extends between end plates  54  and  56  at lower end  32 .  
     [0078] Body portion  23  comprises an outer wall  34 , a concentrically disposed inner wall  36  and a central wall  38  concentrically disposed between outer wall  34  and inner wall  36 . Each of walls  34 ,  36 , and  38  connect with each of end plates  54  and  56 . Disposed between outer wall  34  and central wall  38  is an insulation layer  40 . In one embodiment, insulation layer  40  comprises a chloride free, ceramic fiber capable of withstanding temperatures up to 1,300° C. Other conventional types of insulation can also be used. Extending between central wall  38  and inner wall  36  are a plurality of spaced apart spacers  42 . Spacers  42  can comprise discrete members or formations projecting from central wall  38  and or inner wall  36 . Spacers  42  provide structural stability for both central wall  38  and inner wall  36  while forming fluid channels  44  which allow fluid to flow between central wall  38  and inner wall  36  and around spacers  42 .  
     [0079] More specifically, depicted in FIG. 3 is a cutaway view showing the outside face of inner wall  36  with spacers  42  projecting therefrom. Each of inner wall  36 , central wall  38 , and out wall  34  extend between and rigidly connect with a top plate  70  and an opposing bottom plate  72 . In one embodiment, support brace  58 , previously discussed, can be integrally formed with bottom plate  72 . As will be discussed below in greater detail, a plurality of vertically oriented spaced apart slots  68  extend through body portion  23  from toward bottom plate  72  to toward top plate  70 . Slots  68  generally divide body portion  23  into a plurality of sections  74 . Each of inner wall  36 , central wall  38 , and outer wall  34  also connect with side plates  76  and  78  that bound each side of each slot  68 . As a result, fluid channels  44  are sealed closed in each section  74  of body portion  23 .  
     [0080] To facilitate fluid communication between fluid channels  44  of each section  74 , a transition pipe  80  extends between each section  74  at upper end  30 . Each opposing end of transition pipe  80  is in fluid communication with a corresponding fluid channel  44 . As also depicted in FIG. 3, a plurality of spaced apart, vertically oriented channeling ribs  82  extend between inner wall  36  and central wall  38 . Channeling ribs  82  are positioned such that as fluid flows radially about body portion  23 , the fluid is also forced to flow in a sinusoidal path along the height of body portion  23 .  
     [0081] Specifically, as depicted in FIGS. 1 and 2, a fluid inlet pipe  62  is connected with body portion  23  at lower end  32  adjacent to end plate  54  while a fluid outlet pipe  64  is connected with body portion  23  at lower end  32  adjacent to end plate  56 . Each of inlet pipe  62  and outlet pipe  64  are in fluid communication with fluid channels  44 . As fluid is pumped into fluid inlet pipe  62 , the fluid enters a fluid channel  44  through an inlet port  66  in FIG. 3. As a result of being bounded between side plate  76  and end plate  54 , the fluid travels vertically upward and around spacers  42 .  
     [0082] When the fluid reaches upper end  30 , the fluid passes through transition pipe  80  into the next adjacent section  74 . As the fluid continues to travel around body portion  23  toward fluid outlet pipe  64 , the fluid continues to vertically travel up and down so as to pass around channeling ribs  82 . Once the fluid reaches and is removed from body portion  23  through fluid outlet pipe  64 , the fluid is then heated or cooled, depending on desired operating parameters, and then reintroduced back through fluid inlet pipe  62 . In one embodiment, the fluid passing through fluid channels  44  is a mixture of water and propylene glycol. In other embodiments, the fluid can be any material that can be used for heating and/or cooling.  
     [0083] In one embodiment of the present invention, means are provided for selectively heating or cooling a solution held within chamber  60  of tank assembly  20 . One example of such means comprises fluid channels  44  and related structure as discussed above. As will be discussed below in greater detail, during operation a solution is disposed within chamber  60 . By running a fluid through fluid channels  44  with the fluid at a desired temperature, the fluid acts as either a heat sink by drawing energy from the solution through inner wall  36  or as a heat source by inputting energy into the solution through inner wall  36 , thereby heating or cooling the solution.  
     [0084] In part, channeling ribs  82  function to uniformly distribute the fluid over the exterior surface of inner wall  36  so as to uniformly control the temperature of the solution within chamber  60 . In this regard, channeling ribs  82  and fluid channels  44  can be oriented to flow in a variety of different paths. Furthermore, body portion  32  can be formed without channeling ribs  82 .  
     [0085] In yet other alternative embodiments for the means for selectively heating and cooling, open fluid channels  44  can be replaced with piping that runs on the interior, exterior, and/or within inner wall  36 . The piping is configured to have the heating or cooling fluid run therethrough. Electrical heating elements can also be positioned on the interior, exterior, and/or within the inner wall  36  to facilitate heating of solutions within chamber  60 . In yet another embodiment, the solution within chamber  60  can be pumped out of chamber  60  where it is then selectively heated or cooled through conventional systems and then cycled back into chamber  60 .  
     [0086] As depicted in FIGS. 1, 2 and  2 A, side wall  24  also comprises a door  25  disposed within doorway  57  between end plates  54  and  56 . As with body portion  23 , door  25  comprises an outer wall  34  and an inner wall  36 . In this embodiment, however, door  25  does not include a central wall  38 . Rather, a layer of insulation  40  is disposed between walls  34  and  36 . In an alternative embodiment, door  25  can also include fluid channels  44  which communicate with body portion  23  through flexible hose connections.  
     [0087] A vertically oriented, elongated viewing slot  46  extends through a portion of door  25 . A window  48  is disposed within viewing slot  46  so as to seal viewing slot  46  closed but provide an unobstructed view of chamber  60 . Door  25  is mounted to body portion  23  by hinges  50 . A handle  52  is formed on door  25  to facilitate hinged movement of door  25  between an open position (not shown) wherein free access is provided to chamber  60  through open doorway  57  and a closed position wherein door  25  closes off doorway  57 .  
     [0088] In one embodiment of the present invention, means are provided for selectively locking door  25  in the closed position. By way of Example and not by limitation, as depicted in FIGS. 2A and 4, a vertically oriented, tubular housing  90  is movable mounted along end plate  56  of body portion  23 . Housing  90  has a front face with a plurality of vertically spaced apart stops  102  formed thereon. Each stop  102  has an engagement face  104  that slopes toward chamber  60 .  
     [0089] An actuation rod  92  extends through housing  90  in parallel alignment therewith. Actuation rod  92  is rigidly secured to housing  90  by bolts  94  or the like and extends between a first end  96  and an opposing second end  98 . First end  96  of actuation rod  92  projects up above tubular housing  90 . Second end  98  of actuation rod  92  is coupled with a hydraulic piston  100  disposed below support brace  58 . By selectively operating hydraulic piston  100 , actuation rod  92  is selectively raised and lowered which in turn selectively raises and lowers housing  90 .  
     [0090] Projecting from a side face  105  of door  25  are a plurality of vertically oriented and spaced apart locking flanges  106 . Each locking flange  106  is separated by a gap  108 . To facilitate locking of door  25 , actuation rod  92  is moved to a lowered position and door  25  is moved to the closed position. In this configuration, locking flanges  106  are disposed between stops  102 . Hydraulic piston  100  is then used to elevate actuation rod  92 . In so doing, housing  90  and stops  102  rise so that engagement face  104  of each stop  102  biases against a corresponding locking flange  106 . Engagement faces  104  are sloped so as to bias locking flanges  106  radially inward, thereby locking door  25  closed. To further secure this locking, a plate  108  having a hole extending therethrough projects from the upper end of door  25 . When door  25  is in the closed position the hole in plate  108  is aligned with actuation rod  92 . As actuation rod  92  rises, first end  96  of actuation rod  92  passes through the hole in plate  108 .  
     [0091] It is appreciated that the means for selectively locking door  25  can have a variety of alternative configurations. By way of example and not by limitation, hydraulic piston  100  can be replaced by a pneumatic piston, gear or belt drive, crank, jack, or other drive mechanism. Furthermore, is appreciated that locking flanges  106  and stops  102  can be switched or replaced with a variety of other conventional interlocking members. In other embodiments, a variety of shafts can be positioned so as to selectively drive from one of door  25  or body portion  23  into or against the other thereof Hand operated dead bolts and other conventional locking structures can also be used.  
     [0092] B. Floor.  
     [0093] Returning back to FIGS. 1 and 2, tank assembly  20  further comprises a floor  110  disposed within or within alignment of the interior of side wall  24 . Floor  110  comprises a substantially flat base floor  112 . In the embodiment depicted, base floor  112  is circular and extends to a perimeter edge  114 . As will be discussed below in greater detail, a plurality of open port holes  116  extend through base floor  112 . A central port hole  117  also extends through base floor  112 . Although not required, a plurality of screened spill holes  118  are also formed on base floor  112 .  
     [0094] A peripheral wall  120  upwardly and outwardly slops from perimeter edge  114  of base floor  112  to a terminal edge  122 . Outwardly projecting from terminal edge  122  is a lip  124 . Lip  124  is either biased directly against or terminates directly adjacent to interior surface  26  of side wall  24 . Except for lip  124 , the remainder of floor  110  and the walls of side wall  24  are typically made of a metal such as stainless steel. In contrast, lip  124  is typically made of polypropylene but can also be made of resilient materials such as rubber, silicone, Vitor, Teflon, and other moldable plastics.  
     [0095] In the embodiment depicted, floor  112  has a substantially frustoconical configuration. In alternative embodiments, floor  112  can be entirely flat, curved, pyramidal, conical, or any other desired configuration that can support a bag as discussed below. Furthermore, floor  112  need not be circular but can be polygonal, elliptical, irregular, or any other desired configuration.  
     [0096] In one embodiment of the present invention, means are provided for selectively raising and lowering floor  112  relative to side wall  24 . By way of example and not by limitation, rotatably mounted on the exterior of side wall  24  in vertical alignment with each slot  68  thereof is a threaded shaft  130 . In one embodiment, a driver  138  is mounted at the bottom of each shaft  130  to selectively rotate each shaft  130 . A collar  134  encircles and threaded engages each shaft  130  such that rotation of each shaft  130  causes each corresponding collar  134  to advance up or down the length of shaft  130 , depending on the direction of rotation, in a worm drive configuration. A strut  136  extends between floor  120  and each collar  134  so as to pass through a corresponding slot  68 . As a result, simultaneous rotation of each shaft  130  facilitates uniform raising and lowering of floor  112  relative to side wall  24 . By adjusting the level of floor  112 , the size of chamber  60  bounded by side wall  24  and floor  60  is selectively adjusted, i.e., the size of chamber  60  gets smaller as floor  112  rises.  
     [0097] It is appreciated that the means for selectively raising and lowering floor  112  can comprises a variety of modified and alternative configurations. For example, rather than having a separate driver  132  for each threaded shaft  130 , a single driver  132  can be used which is connected by drive lines  140  (shown in FIG. 2) to each separate threaded shaft  130 . In yet other modifications, shaft  130  and collars  134  can be replaced with one or more conventional chain drives, belt drives, gear drives, hydraulic lifts, pneumatic lifts, jacks, cranks, winches, pulley systems and/or combinations thereof and the like for selectively raising struts  136  from the exterior of side wall  24 . Furthermore, the above discussed various lifts and jacks can be placed directly below floor  112  for selectively raising and lowering floor  112 . In these embodiments, struts  136  and slots  68  are not required but may be used for stabilizing.  
     [0098] C. Slot Cover Assembly.  
     [0099] In one embodiment of the present invention, means are provided for selectively covering and uncovering portions of slots  68  within chamber  60 . As will be discussed below in greater detail, because a bag or other form of liner is typically disposed within chamber  60  of tank assembly  20 , in one embodiment it is desired, although not required, that a cover be disposed over that portion of slots  68  that is exposed above floor  11 I so that the bag or liner does not bulge out of or catch on slots  68  and potentially fail. As depicted in FIGS. 5A and 5B, one example of such means comprises a slot cover assembly  149  that includes an elongated flexible slot cover  150  having a first end  152  and an opposing second end  154 . Slot cover  150  has a width slightly larger than slot  68  (as seen in FIG. 2) and a thickness which is typically in a range between about 2 mm to about 10 mm. Other desired thicknesses can also be used.  
     [0100] First end  152  of slot cover  150  is positioned against or adjacent to interior surface  26  of side wall  24  at or adjacent to lip  124  of floor  110 . In one embodiment, at least a portion of first end  152  of slot cover  150  is disposed between lip  124  and side wall  24 . First end  152  of slot cover  150  is held in position by a bracket  156  mounted on strut  136 . Alternatively, slot cover  150  can be mounted directly to floor  110  or strut  136 . From first end  152 , slot cover  150  freely travels upward so as to movably and substantially cover that portion of slot  68  above floor  110 . A rounded support  158  is mounted on top plate  70  of body portion  23 . Slot cover  150  passes over rounded support  158  and travels down along the exterior of side wall  24  to second end  154 .  
     [0101] Slot cover assembly  149  also includes a tensioning spring  158  and a line  160 . One end of tensioning spring  158  is connected to second end  154  of slot cover  150 . A first end  162  of line  160  is connected to the opposing end of tensioning spring  158 . Line  160  extends down through a support loop  164  mounted on base plate  72  of body portion  23 . A second end  166  of line  160  then connects back to strut  136  such as by bolting, welding, bracket, or the like. Since slot cover assembly  149  forms a continuous loop with opposing ends connecting to strut  136 , raising or lowering of floor  110  causes slot cover  150  to move along and continuously cover slot  68  above lip  124  of floor  110 . This configuration, however, also allows slot  68  below lip  124  of floor  110  to be open so as to allow the free travel of strut  136  therein.  
     [0102] Line  160  of slot cover assembly  149  can be wire, cable, rope or the like. In an alternative embodiment, line  160  can be replaced with the same material as slot cover  150 . Line  160  is simply used so as to be less obstructive. In yet other embodiments of the means, a spring tensioned coil, electrical winch, or the like can be disposed on the top or outside of side wall  23  so as to selectively gather and release slot cover  150  as floor  110  is selectively raised and lowered.  
     [0103] D. Mixer Drivers.  
     [0104] As depicted in FIG. 1, extending through central port hole  117  of floor  110  (FIG. 2) is a mixing shaft  208 . As will be discussed and depicted below in greater detail, a mixer is mounted on the first end of mixing shaft  208  within chamber  60 . In one embodiment of the present invention, means are provided for selectively raising and lowering mixing shaft  208 . By way of example and not by limitation, a frame  168  is mounted to and extends below floor  110 . Mounted to frame  168  is a hydraulic piston  170  which operates an actuation rod  172 . In turn, a coupler  176  removably connects actuation rod  172  to mixing shaft  208 . Flexible hydraulic hoses  174  provide hydraulic fluid to hydraulic piston  170  for raising and lowering actuation rod  172  and thus mixing shaft  208 . As a result of hydraulic piston  170  being mounted to floor  110  by way of frame  168 , hydraulic piston  170  raises and lowers with floor  110 .  
     [0105] It is appreciated that there are a number of alternative embodiments of the means for selectively raising and lowering mixing shaft  208 . By way of example and not by limitation. Hydraulic piston  170  can be mounted on platform  12  or a ground surface. This embodiment is more practical where floor  110  is fixed. Furthermore, hydraulic piston  170  can be replaced with a number of other forms of drivers such as a pneumatic piston, rotating crank, various forms of belt drivers, chain drivers, or gear drivers, or other well known mechanisms that enable repeated raising and lowering of a shaft. It is also appreciated that such drivers can be directly connected to mixing shaft  208  or can be connected thereto through actuation rod  172 .  
     [0106] E. Fixed Tank Configuration  
     [0107] In alternative embodiments of tank assembly  20 , it is appreciated that floor  110  need not be adjustable nor does tank assembly  20  need to be able to heat or cool the solution disposed therein. For example, depicted in FIGS. 6 and 7 is a tank assembly  178 . Tank assembly  178  comprise a substantially frustaconical floor  180  having a plurality of support legs  182  downwardly extending therefrom. Rigidly connected to and upwardly extending from the perimeter of floor  180  is an annular side wall  184 . Floor  180  and side wall  184  bound a chamber  183 .  
     [0108] Floor  180  comprises a central base floor  185  having port holes  116  and central port hole  117  extending therethrough. Base floor  185  has a hexagonal configuration that terminates at a plurality of perimeter edges  186 . A trapezoidal shaped floor panel  187  upwardly extends at an angle from each perimeter edge  186  of base floor  185 . Each of floor panels  187  are secured, such as by welding, bolting, or the like, to the adjacent floor panels  187 . The resulting floor  185  thus has a substantially frustaconical configuration with an interior surface, an exterior surface, and a perimeter edge each having a substantially hexagonal transverse cross section.  
     [0109] Side wall  184  comprises a plurality of side panels  188  each having a substantially rectangular configuration. Each side panel  188  is rigidly connected to and upwardly extends from an outer perimeter edge of a corresponding floor panel  187 . Again, adjacent side panels  188  are connected to each other and to floor panels  187  such as by welding, bolting, or the like. Side wall  184  thus has an interior surface and an exterior surface each having a substantially hexagonal transverse cross section along the length of side wall  184   
     [0110] In contrast to tank assembly  20 , floor  180  and side wall  184  of tank assembly  178  are made of solid sheets of metal or other material and thus do not bound fluid channels  44  nor do they have slots  68  extending therethrough. Furthermore, side wall  184  does not include a door or window. Finally, floor  180  is rigidly connected to side wall  184  and thus does not raise or lower relative to side wall  184 .  
     [0111] In both tank assembly  20  and tank assembly  178 , the side wall and floor can be any desired configuration such as elliptical, polygonal, irregular, or any other desired configuration. The floor typically has a configuration complementary to the side wall. In alternative embodiments, it is appreciated that the various features of tank assemblies  20  and  178  can be mixed and matched so as to produce a variety of tank assembly configurations having different properties. For example, a tank assembly can be made to heat or cool a solution but have a fixed floor that does not raise or lower. Furthermore, tank assemblies can be made in any number of different sizes. For example, tank assemblies can be made with a chamber having a volume of 20 liters, 250 liters, 500 liters, 750 liters, 1,000 liters, 1,500 liters, 3,000 liters, 5,000 liters, 10,000 liters or other sizes. In addition, fluid preparation system  10  can comprise two or more tank assemblies of the same or different size, shape, and/or properties that are mounted on or off of platform  12 .  
     [0112] II. Mixing Assembly.  
     [0113] Depicted in FIG. 8 is one embodiment of a mixing assembly  200 . In general, though not required or exclusive, mixing assembly  200  comprises a mixing bag  202 , a mixer  204  configured to be disposed within mixing bag  202 , and an expandable tubular seal  206  configured to provide a fluid sealed connection between mixing bag  202  and mixer  204 . In alternative embodiments, mixing shaft  208 , as previously discussed, can either be part of or separate from mixing assembly  200 .  
     [0114] A. Mixing Bag.  
     [0115] As depicted in FIG. 8, mixing bag  202  comprises an elongated, bag-like body  203  having an interior surface  210  and an exterior surface  212 . Interior surface  210  bounds a compartment  220 . More specifically, body  203  comprises a side wall  213  that, when body  203  is inflated, has a substantially circular or rounded polygonal transverse cross section that extends between an upper end  214  and an opposing lower end  216 . Upper end  214  terminates at a top end wall  215  while lower end  216  terminates at a bottom end wall  217 .  
     [0116] Body  203  is comprised of a flexible, water impermeable material such as polyethylene, polyurethane or other polymeric sheets having a thickness in a range between about 0.1 mm to about 5 mm with about 0.2 mm to about 2 mm being more common. Other thicknesses can also be used. In one embodiment, the material is approved for direct contact with living cells and is capable of maintaining a solution sterile. In such an embodiment, the material should also be sterilizable such as by ionizing radiation. Examples of materials that can be used are disclosed in U.S. Pat. No. 6,083,587 which issued on Jul. 4, 2000 and U.S. patent application Ser. No. 10/044,636, filed Oct. 19, 2001 which are hereby incorporated by specific reference.  
     [0117] Body  203  can be comprised of a single ply material or can comprise two or more layers which are either sealed together or separated to form a double wall container. In one embodiment, body  203  comprises a two dimensional bag wherein two sheets of material are placed in overlapping relation and the two sheets are bounded together at their peripheries to form internal compartment  220 . In the embodiment depicted, however, body  203  comprises a three dimensional bag which not only has an annular side wall  213  but also a two dimensional top end wall  215  and a two dimensional bottom end wall  217 .  
     [0118] Three dimensional body  203  comprises a plurality, i.e., typically three or more, discrete panels  228  as shown in FIG. 9. Each panel  228  is substantially identical and comprises a portion of the side wall  213   a , top end wall  215   a , and bottom end wall  217   a . Corresponding perimeter edges of each panel  228  are seamed together to form seams  230  as shown in FIG. 8. Seams  230  are formed using methods known in the art such as heat energies, RF energies, sonics, or other sealing energies.  
     [0119] In alternative embodiments, panels  228  can be formed in a variety of different patterns. Further disclosure with regard to one method of manufacturing three-dimensional bags is disclosed in U.S. patent application Ser. No. 09/813,351, filed on Mar. 19, 2001 of which the drawings and Detailed Description are hereby incorporated by reference.  
     [0120] By using discrete panels  228 , it is appreciated that body  203 , and thus mixing bag  202 , can be manufactured to have virtually any desired size, shape, and configuration. For example, mixing bag  202  can be formed having compartment  220  sized to hold 20 liters, 250 liters, 500 liters, 750 liters, 1,000 liters, 1,500 liters, 3,000 liters, 5,000 liters, 10,000 liters, or other desired amounts. Body  203  is often made of four or six panels  228  depending on the intended volume of mixing bag  202 . Mixing bag  202  simply conforms to the configuration of tank assembly  20  as it is filled with solution. In one embodiment, however, mixing bag  202  can be specifically configured to be complementary to the interior surface of tank assembly  20  bounding chamber  60 . For example, when interior surface of side wall  24  has a hexagonal configuration, mixing bag  202  can be made of six panels  228  so as to have a substantially hexagonal transverse cross section.  
     [0121] In either event, when mixing bag  202  is received within chamber  60 , body  203  is uniformly supported by floor  110  and side wall  24  of tank assembly  20 . This substantially uniform support of body  203  by tank assembly  20  helps to preclude failure of any mixing bag  202  by hydraulic forces applied to body  203  when mixing bag  202  is filled with a solution.  
     [0122] Depicted in FIG. 10A, mixing bag  202  further comprises a feeding port  222 , a barbed fluid port  224 , and an barbed pressure port  226  each mounted on top end wall  215  of body  203  so as to outwardly project therefrom. An annular flange  223  encircles and outwardly projects from the free end of feeding port  222 . A channel  227  extends through each of ports  222 ,  224 , and  226  so as to provide fluid communication between compartment  220  and the exterior.  
     [0123] A flexible extension sleeve  239  is received over feeding port  222  and is connected thereto by a tie  241 . A tubular coupling  243  is mounted at the opposing end of sleeve  239  and is also secured thereto by a tie  241 . A removable clamp  245  is closed across extension sleeve  239  so as to close off fluid communication between compartment  220  and the exterior. Extension tubes  249  and  251  are coupled to ports  224  and  226 , respectively. A tie  241  can also be used to secure each of these connections. A removable clamp  244  is also closed across each tube  249  and  251  so as to seal off fluid communication between compartment  220  and the exterior.  
     [0124] Depicted in FIG. 10B is an alternative embodiment wherein like elements are identified by like reference characters. In this embodiment, extension sleeve  239  and clamp  244  have been replaced with a cover plate  232 . Cover plate  232  is disposed within compartment  220  and is rotatably mounted to or adjacent to feeding port  222  by way of a knob  234 . Selective rotation of a free end of knob  234  projecting outside of bag  202  facilitates rotation of cover plate  232  within compartment  220 . Cover plate  232  can be rotated to selectively cover or expose channel  227  extending through feeding port  232 .  
     [0125] Depicted in FIG. 11, mounted on bottom end wall  217  of body  203  so as to outwardly project therefrom is a barbed inflation port  236 , a barbed outlet port  238 , and a barbed inlet port  240 . A barbed mounting port  242  is centrally disposed on bottom end wall  217  and projects into compartment  220 . A channel  227  also extends through each of ports  236 ,  238 ,  240 , and  242  so as to provide fluid communication between compartment  220  and the exterior. If desired, extension tubes with clamps thereon can be mounted on ports  236 ,  238  and  240 , such as discussed with ports  224  and  226 , so as to close communication with chamber  220  prior to use of mixing bag  202 .  
     [0126] Although in the above discussed embodiments mixing bag  202  has a flexible, bag-like configuration, in alternative embodiments it is appreciated that mixing bag  202  can comprise any form of collapsible container or rigid container.  
     [0127] B. Mixer.  
     [0128] In one embodiment of the present invention means are provided for mechanically mixing a liquid solution with compartment  220  of mixing bag  202 . By way of example and not by limitation, mixer  204  is disposed within compartment  220  of mixing bag  202 . As depicted in FIG. 11, mixer  204  comprises a base  205  having flaps  264  mounted thereagainst. More specifically, base  205  comprises a central hub  246  having an exterior surface  247  extending between a first end  248  and an opposing second end  250 . Second end  250  terminates at an end face having a threaded recess  252  formed thereon. Barbs  254  encircle and radially outwardly project from hub  246  at second end  250 .  
     [0129] As depicted in FIG. 12, base  205  further includes a plurality of spaced apart struts  256  that radially outwardly project from the exterior of hub  246  at first end  248  to an annular rim  258 . A retention screen  260 , supported on or by struts  256 , extends between hub  246  and rim  258 . Retention screen  260  bounds a plurality of fluid openings  259  formed between hub  246  and rim  258 . In the embodiment depicted, retention screen  260  is comprised of wire or other line that is strung between struts  256 . In alternative embodiments, retention screen  260  can comprise various forms of mesh, matting, conventional screen, plates having slots, holes, or other types of openings extending therethrough, or other similar types of structures that can support flaps  264 , as discussed below, but which enable fluid to pass therethrough.  
     [0130] As depicted in FIGS. 1I and 13A, a plurality of spaced apart spokes  262  also extend between hub  246  and rim  258 . Each spoke  262  is aligned with a corresponding strut  256  on a side thereof closer to second end  250  of hub  246 . Positioned between each spoke  262  and retention screen  260  is a flexible wedge shaped flap  264 . Each flap  264  has a pointed lead end  266  disposed against or adjacent to hub  246  and a flared tail end  268  disposed adjacent to rim  258 . Each flap  264  also comprises opposing diverging sides  270  and  272  that extend from lead end  266  to tail end  268 . Each flap  264  is positioned so that a corresponding spoke  262  extends between lead end  266  and tail end  268  centrally between sides  270  and  272 . Flaps  264  are configured to completely or at least substantially cover fluid openings  259  formed between hub  246  and rim  258  when flaps  264  rest against retention screen  260 . In one embodiment, flaps  264  are comprised of a sheet of silicone having a thickness in a range between about 1 mm to about 10 mm. Other flexible sheets of material, such as polyethylene or polyurethane, having a variety of different thicknesses can also be used.  
     [0131] As shown in FIG. 11, mixer  204  is supported within compartment  220  of mixing bag  202  by mixing shaft  208 . Specifically, mixing shaft  208  has a threaded first end  278  and an opposing second end  280 . First end  278  of mixing shaft  208  slidably passes through channel  227  of mounting port  242  and then screws into threaded recess  252  of hub  246 . Second end  280  of mixing shaft  208  is disposed outside of mixing bag  202 .  
     [0132] In one embodiment of the present invention means are provided for raising and lowering mixer  204  within compartment  220  of mixing bag  202  so as to mix the solution within compartment  220 . One embodiment of such means comprises mixing shaft  208  as discussed above. Alternative embodiments of such means include alternative mixing shafts as disclosed herein.  
     [0133] The present invention also includes means for enabling mixing shaft  208  to raise and lower mixer  204  within compartment  220  of bag  202  while preventing leaking of liquid from compartment  220  of mixing bag  202 . By way of example and not by limitation, tubular seal  206  has a first end  284 , an opposing second end  286 , and an expandable bellow section  288  extending therebetween. First end  284  of seal  206  encircles second end  250  of hub  246 . A surrounding tie  290  is used to secure the connection in a liquid tight fashion. Similarly, second end  286  of seal  206  encircles mounting port  242 . A tie  292  is also used to secure this connection in a liquid tight fashion.  
     [0134] In the assembled configuration shown in FIG. 11, mixing shaft  208  can freely slide within channel  227  of mounting port  242  such that by selectively raising and lowering mixing shaft  208  from outside of mixing bag  202 , mixer  204  is correspondingly raised and lowered within compartment  202  relative to mixing bag  202 . Bellow section  288  of seal  206  selectively expands and contracts as mixing shaft  208  is raised and lowered relative to mixing bag  202 , thereby maintaining the sealed communication between mixer  204  and mounting port  242 .  
     [0135] As will be discussed below in greater detail, mixing of a solution within compartment  220  of mixing bag  202  is accomplished by repeatedly raising and lowering mixer  204  within compartment  220 . As shown in FIG. 13B, as mixer  204  is raised, fluid within compartment  220  passes through retention screen  260  and pushes against flaps  264  causing sides  270  and  272  of flaps  264  on opposing sides of spokes  262  to downwardly flex, thereby allowing mixer  204  to travel through the fluid without substantial disturbance. As mixer  204  begins to travel downward, as shown in FIG. 13A, the fluid pushes flaps  264  against retention screen  260  so as to preclude the passage of the fluid through fluid openings  259  of mixer  204 . As such, downward movement of mixer  204  causes the fluid within compartment  220  to flow down, out, up, and around as shown by arrow  294  in FIG. 11. As the process of raising and lowering mixer  204  is repeated, swirling motion of the solution caused by mixer  204  mixes the solution.  
     [0136] Mixing parameters can be varied based on the amount and type of solution being prepared. For example, the stroke length, i.e., the vertical distance that mixer  204  travels, and the frequency, i.e., the number of times mixer  204  travels the stroke length per unit of time, and the acceleration and deceleration, i.e., the rate at which mixer  204  starts and stops, can each be selectively regulated. The stroke length and frequency can not only be changed between different batches but can also be changed at different times during the mixing of a single batch. Furthermore, if desired, one or more of the variables can be continually changed during mixing.  
     [0137] In one embodiment, the parameters are set so as to enable rapid and thorough mixing of the components and yet be gentle enough to maintain suspensions for extended period of time without inducing excess foaming. By way of example and not by limitation, in one embodiment the stroke length is in a range between about 0.1 cm to about 30 cm with about 5 cm to about 20 cm being more common while the frequency is in a range between about 0.1 Hz to about 4 Hz with about 0.5 HHz to about 2 Hz being more common. Other parameter settings, however, can also be used based on the configuration of the mixer and the amount and type of solution being prepared.  
     [0138] It is appreciated that the means for mechanically mixing a liquid solution with compartment  220  of mixing bag  202  can comprise a variety of modifications or alternative embodiments of mixer  204 . For example, in one embodiment mixer  204  can be flipped so that swirling is produced in an opposite direction. Furthermore, flaps  264  are simply functioning as a one-way valve. It is appreciated that there are a variety of alternative ways to form one-way valves on mixer  204 . For example, rather than having flexible flaps  264 , rigid flaps can be hingedly mounted on mixer  204 . Furthermore, pneumatic, hydraulic, or electrical switches can be coupled with mixer  204  which selectively open and close one-way valves on mixer  204 . In this embodiment, the oneway valves may simply comprise plates which selectively slide to open or close one or more holes extending through mixer  204 .  
     [0139] In another alternative embodiment, it is appreciated that mixer  204  can be formed without one-way valves. For example, mixer  204  can comprise a rigid or flexible plate with no openings. In this embodiment, the plate swirls or otherwise mixes the solution as the plate moves in both directions. In yet another embodiments, the plate can have fixed holes or slots therein to direct movement of the fluid. Likewise, mixer  204  can simply comprise a plurality of fixed fins or vanes which can be configured to either rotate and/or move up and down within mixing bag  202  for mixing the solution. In still other embodiments, two or more mixers  204  can be mounted on mixing shaft  208 . For example, the mixers  204  can be longitudinally spaced apart along shaft  208 .  
     [0140] In other embodiments of the means for mixing, mixers can be used that do not operate by being raised and lowered. For example, shaft driven blades and magnetically operated stir bars that rotate within mixing bag  202  can be used.  
     [0141] Depicted in FIG. 14A is one alternative embodiment of a mixer  310 . Mixer  310  comprises a base  312  having flaps  314  connected thereto. Base  312  has a substantially circular plate-like configuration having a top surface  316  and an opposing bottom surface  318 . As depicted in FIG. 15, base  312  includes an integrally formed central hub  322  and integrally formed struts  324  that radially outwardly project from hub  322  to an outer edge  326 . Struts  324  divide base  312  into a plurality of wedge shaped sections  328 . Formed within each section  328  so as to extend between top surface  316  and bottom surface  318  are a plurality of fluid openings  330 .  
     [0142] Base  312  is typically made of a polymeric material, such as high density polyurethane or polyethylene, but can also be made of metal, composite, or other desired materials. Base  312  can be molded having fluid openings  330  formed thereon. Alternatively, base  312  and/or fluid openings  330  can be cut. In one embodiment, base  312  has a thickness between surfaces  316  and  318  in a range between about 1 cm to about 6 cm with about 2 cm to about 4 cm being more common. Other dimensions can also be used depending on size and use parameters.  
     [0143] As depicted in FIG. 16, flaps  314  are mounted on bottom surface  318  of base  312 . Flaps  314  have substantially the same configuration as flaps  264 . In this embodiment flaps  314  are comprised of polyethylene sheets having a thickness in a range between about 0.1 mm to about 5 mm with about 0.2 mm to about 2 mm being more common. Again, other materials and thicknesses can be used. In contrast to thin ¢ mixer  204  where flaps  264  are held in place by spokes  262 , flaps  314  are directly welded to base  312 . That is, each flap  314  is welded, such as by heat, sonic, chemical welding or the like, along a central axis  332  to a corresponding strut  324 . Each flap  314  is configured to overlay half of each adjacent section  328  with the side edges of each flap  314  being free to flex. Flaps  314  can thus operate in the same fashion as previously discussed with regard to flaps  264 .  
     [0144] As depicted in FIG. 17, a blind hole  336  is formed on bottom surface  318  of hub  322  of base  312 . Blind hole  336  has a frustaconical configuration that tapers outwardly toward top surface  316 . The taper is typically in a range between 1° to about 10° although other angles can also be used. A tubular connector  340  has a first end disposed on bottom surface  318  so as to encircle blind hole  336  and has a barbed annular second end downwardly projecting therefrom. Tubular connector  340  can be integrally formed with or connected to base  312 .  
     [0145] Returning to FIG. 14A, a tubular port  344  has a flanged first end  346  that is welded or otherwise secured to mixing bag  202  and has a barbed second end  348  that outwardly projects from mixing bag  202 . A tubular seal  350  has a first end  352  and an opposing second end  354 . First end  352  is received over the second end of tubular connector  340  so as to form a sealed connection therewith. Second end  354  of seal  350  is passed through tubular port  344  and then turned inside-out so as to enclose barbed second end  348  of tubular port  344  and form a sealed connection therewith. Tubular seal  350  is typically made of a polymeric material, such as polyethylene, having a thickness in a range between about 0.5 mm to about 10 mm with about 0.75 mm to about 3 mm being more common. Other flexible materials and thicknesses can also be  
     [0146] A mixing shaft  358  is shown removably connected to mixer  310 . Mixing shaft  358  has a first end  360  and an opposing second end  362 . Returning to FIG. 17, a tubular collet  363  projects from first end  360  of shaft  358 . Collet  363  has an exterior surface  364  with threads formed thereon and an interior surface  365  that bound a socket  366 . A plurality of radially spaced apart slot  376  extend between surfaces  364  and  365  along the length thereof. Disposed within socket  336  is a frustaconical wedge  368  having a first end  369  and an opposing second end  370 .  
     [0147] Prior to coupling mixing shaft  358  to mixer  310 , collet  363  has a substantially cylindrical configuration with socket  366  being sized only to receive the smaller second end  370  of wedge  368 . During assembly, first end  360  of mixing shaft  358  having wedge  368  partially received within socket  366  is passed through tubular seal  350  and into blind hole  336  of base  312 . As collet  363  is further pressed into blind hole  336 , first end  369  of wedge  368  biases against the bottom of blind hole  336 . In turn, wedge  368  is pressed further into socket  366  causing collet  363  to radially outwardly expand so that the threaded exterior surface  364  of collet  363  engages against the interior surface of blind hole  336 . By further pressing wedge  368  within collet  363 , first end  360  of mixing shaft  358  becomes securely connected to base  312 . However, once use of mixing bag  202  is completed, mixing shaft  358  can be rotated so that collet  363  unscrews from base  312 , thereby enabling reuse of mixing shaft  358 .  
     [0148] The above embodiment enables relatively easy attachment of mixing shaft  358  to mixer  310  positioned within mixing bag  202  without fear of cross threading. In alternative embodiments, however, it is appreciated that mixing shaft  358  can be connected to mixer  310  using conventional connections, such as threaded engagement, or can be permanently secured to mixer  310 .  
     [0149] Returning to FIG. 14A, once mixing shaft  358  is secured to mixer  310 , mixing shaft  358  can be used for selectively raising and lower mixer  310  for mixing the solution within compartment  202 . In contrast to expansion and contraction of bellow section  288  of tubular seal  206  (FIG. 9), tubular seal  350 , as shown in FIGS. 14A and  14 B progressively turns inside-out and then turns back rightside-in as shaft  358  is raised and lowered. Tubular seal  350  is thus another example of a means for enabling a mixing shaft to raise and lower a mixer within compartment  220  of bag  202  while preventing leaking of liquid from compartment  220  of mixing bag  202 .  
     [0150] Depicted in FIG. 18A is another alternative embodiment of a mixer  374  having a mixing shaft  376  attached thereto. Like elements between mixer  374  and mixer  310  are identified by like reference characters. Mixer  374  is substantially identical to mixer  310  except that base  378  of mixer  374  does not include blind hole  336  or tubular connector  340 . Rather, base  378  has a through hole  380  formed through hub  322 . A bolt  381  is disposed on top surface  316  of base  378  such that a threaded shaft  382  thereof is received within through hole  380 . Mixing shaft  376  has a first end  383  and an opposing second end  384 . A threaded socket is recessed within first end  383  of mixing shaft  376 . First end  383  of mixing shaft  376  is positioned within through hole  380  and threadedly engaged with bolt  381 . An annular flange  385  outwardly projects from mixing shaft  376  and biases against bottom surface of base  378 , thereby preventing mixing shaft  376  from passing through base  378 . In this embodiment, mixing shaft  376  is designed to be permanently attached to mixer  374 . Again, mixing shaft  376  can be connected to mixer  374  using any conventional attachment mechanisms such as welding, integrally forming, screwing, clipping, and the like.  
     [0151] Mounted on or toward second end  384  of mixing shaft  376  is a flexible diaphragm  388 . In one embodiment diaphragm  388  is molded from polyurethane. Other flexible materials can also be used. Diaphragm  388  has a hollow semi-spherical configuration that includes an outer annular base  389  with an annular flange  390  radially outwardly projecting therefrom. Flange  390  is sealed, such as by welding or other conventional techniques, to mixing bag  202  so that diaphragm  388  communicates with compartment  220  of mixing bag  202 . Diaphragm  388  also includes a central portion  391  having a tubular sleeve  392  projecting therefrom. A plurality of ribs  393  encircle and radially outwardly project on mixing shaft  376  at or toward second end  384  thereof. Sleeve  392  of diaphragm  388  is passed over ribs  393  so that a sealed connection is formed between mixing shaft  376  and diaphragm  388 . A tie  394  can be secured around sleeve  392  to ensure the sealed connection.  
     [0152] In this configuration, diaphragm  388  is another example of the means for enabling a mixing shaft to raise and lower a mixer within compartment  220  of mixing bag  202  while preventing leaking of liquid from compartment  220  of mixing bag  202 . Specifically, as depicted in FIGS. 18A and 18B, as mixing shaft  376  is selectively raised and lowered so as to raise and lower mixer  374 , diaphragm  388  freely flexes in and out so as to allow free movement of mixing shaft  376 .  
     [0153] It is appreciated that the various mixers, shafts, and/or seals and components thereof can be mixed and matched to create a variety of other alternative embodiments. It is also noted that the first end of seals  206  and  350  can be coupled in a sealed connection directly to mixing shafts  208  and  358 , respectively, as opposed to the corresponding mixers.  
     [0154] III. Positioning Mixing Assembly in Tank Assembly.  
     [0155] In one embodiment, mixing assembly  200  is manufactured and sold as a disposable unit. During manufacture, a portion of panels  228  are seamed together as previously discussed. Prior to complete sealing of panels  228 , however, mixer  204  is positioned within compartment  220 . Seal  206  is then coupled between mixer  204  and mounting port  242  as previously discussed. Once seal  206  is appropriately attached, the remainder of panels  228  are seamed together to complete the production.  
     [0156] As shown in FIG. 19, mixing bag  202  is then collapsed in an accordion fashion and bounded by a harness  296 . Once complete, mixing assembly  200  can be sterilized such as by ionizing radiation or other conventional methods. Depending on the desired solution and the method of manufacture, however, it may not be necessary to sterilize mixing assembly  200 .  
     [0157] Mixing shaft  208  can be mounted to mixer  204  either before mixer  204  is disposed within compartment  220  of mixing bag  202  or at any time after mixer  204  is sealed within compartment  220 . As depicted in FIG. 11, this latter attachment is accomplished by simply passing first end  278  of mixing shaft  208  from exterior of mixing bag  202  up through mixing port  242  and tubular seal  206  and then screwing mixing shaft  208  into mixer  204 . In this embodiment, mixing shaft  208  can either be disposed of after use or removed and reused.  
     [0158] In the embodiments where mixing shaft  208  is considered to be disposable, mixing shaft  208  can be connected to mixer  204  in any conventional manner such as by adhesion, welding, press fit, or can be integrally formed as a portion of hub  246 . Where the first end of seal  206  is coupled with mixing shaft  208  rather then mixer  204 , mixing shaft  208  is coupled with mixer  204  prior to being sealed within compartment  220 . The second end of mixing shaft  208  is then passed down through seal  206  to the exterior of mixing bag  202 .  
     [0159] Mixers  310  and  374  are also position within compartment  220  of mixing bag  202  prior to complete seaming of panels  228 . Likewise, mixing shafts  358  and  376  can also be coupled with corresponding mixers either before or after the mixers are sealed within compartment  220 .  
     [0160] As previously discussed, mixing bag  202  can be manufactured to hold any desired volume of fluid. During use, a manufacturer initially determines how much solution is desired to be manufactured. Based on that determination, a mixing assembly  200  corresponding to the desired volume is selected. Based on the size of the selected mixing assembly  200 , floor  110  of tank assembly  20  is either raised or lowered so that when mixing bag  202  is completely inflated or filled within chamber  60  of tank assembly  20 , top end wall  215  of mixing bag  202  is positioned within upper end  30  of tank assembly  20 .  
     [0161] Once floor  110  is moved to the desired position, mixing assembly  200  is inserted within chamber  60  of tank assembly  20  through open doorway  57 . More specifically, in one embodiment fluid preparation system  10 , as depicted in FIG. 1, further comprises a lift  400  mounted on platform  12 . Lift  400  comprises a tower  402  having an arm  404  mounted thereon. Tower  402  has a longitudinal axis  406  and is configured to rotate about such axis. Similarly, arm  404  is configured to selectively raise and lower along the length of tower  402 . Mounted on arm  404  is a winch  408  operable with a cable  410 . Mounted at the end of cable  410  is a connecter  412 .  
     [0162] To position mixing assembly  200  within chamber  60 , arm  404  and/or cable  408  is lowered so that connecter  412  is attached to harness  296  on mixing assembly  200 . Lift  400  is then used to guide mixing assembly  200  into chamber  60  through doorway  57 . Mixing assembly  200  is lowered within chamber  60  so that as bottom end wall  217  of mixing bag  202  comes to rest on base floor  112  of floor  110 , ports  236 ,  238 , and  240  are aligned with port holes  116 . Likewise, mixing shaft  208  is aligned with and passed through central port hole  117  so as to couple with actuation rod  172  by coupler  176  as previously discussed. Once mixing assembly  200  is seated within chamber  60 , harness  296  is removed and door  25  is closed and locked.  
     [0163] Next, the ports extending through ports holes  116  are coupled with various tubes. For example, a delivery tube  420  is coupled with outlet port  238 . Delivery tube  420  passes through or couples with a first value  422 , a pump  424 , a second valve  426 , and then couples with filtration system  500  which will be discussed below in great detail. Coupled with first valve  422  is a sample tube  428 . A return tube  430  extends between second valve  426  and inlet port  240 .  
     [0164] The term “tube” as used in the specification and appended claims is intended to include conventional flexible hose and tubing which is relatively inexpensive and can be easily replaced, if desired, between the manufacture of different batches or types of solution. The term “tube”, however, is also intended to include rigid piping and other forms of conduits which may be fixed and require sterilization between the manufacture of different batches or types of solution.  
     [0165] Furthermore, the term “valve” as used in the specification and appended claims is broadly intended to include any type or combination of mechanisms which enables selective closing of a fluid or gas path. For example, first valve  422  can comprise a tee joint coupled with two sections of delivery tube  420  and sample tube  428  acting in combination with an external clamp, such as a conventional hose clamp, which can be of manually or otherwise selectively closed around either delivery tube  420  or sample tube  428 . Alternatively, there are a variety of other conventional types of electrical or manual valves that can be used. The use of external clamps or other forms of valves which do not contact the solution have the benefit in that they can be reused without sterilization. However, valves that contact the solution can also be used and then discarded or sterilized. In this regard pump  424  can comprises a peristaltic pump wherein deliver tube  420  passes therethrough without the solution ever contacting the pump. Conventional pumps can also be used, however, where the solution directly contacts the pump.  
     [0166] Coupled with inflation port  236  is an air tube  432 . Air tube  432  is coupled with an air source. In one embodiment, the air source comprises a compressor or some form of tank wherein compressed air is already stored. In the embodiment depicted, a portion of platform  12  is hollow and forms a large storage tank for compressed air. One benefit of using a large storage tank for holding compressed air is that it enables quick inflation of mixing bag  202 . By using platform  12  as the storage tank, the use of space is optimized. Air tube  432  is coupled with platform  12  by way of a valve  434 .  
     [0167] Once air tube  432  is coupled, air or some other form of gas is fed through tube  432  into compartment  220  so as to completely or substantially inflate mixing bag  202  within chamber  60 . As previously discussed, clamps  244  are used in association with ports  222 ,  224 , and  226  so as to seal the ports, thereby enabling inflation of mixing bag  202 . Alternatively, various forms of caps, seals or other forms of stops can be used to temporarily seal the ports. As depicted in FIG. 20, a support rack  436  is mounted to or positioned on upper end  30  of side wall  24  of tank assembly  20  so as to extend at least partially across side wall  24 . A removable clamp  438  is used to secure feeding port  222  (FIG. 10A) to support rack  436 .  
     [0168] Once mixing bag  202  is inflated and secured to support rack  436 , a fluid line  440  is coupled with fluid port  224  either directly or through extension tube  249 . Fluid line  440  is configured for selectively delivering fluid, such as various forms of water, into mixing bag  202 . A pressure regulator  442  is coupled with pressure port  226 , such as through extension tube  251 , so as to selectively control the air pressure within mixing bag  202  within a desired range. In this regard, pressure regulator  442  operates with an air inlet line  444 , which is coupled with a pump or pressurized gas source, for delivering air or other gases into mixing bag  202  and an air outlet line  446  for allowing air to escape from mixing bag  202 . A filter  447  is coupled with outlet line  446  to prevent particulate feed component within mixing bag  202  from escaping with the exiting air.  
     [0169] The above described process is typical for placement of a relatively large mixing bag within a tank assembly having a movable floor. For tank assembly  178  shown in FIGS. 6 and 7 where the floor is fixed to the side wall, mixing bag  202  is typically sized so as to have a volume corresponding to the volume of the chamber of tank assembly. In general, such systems can efficiently mix fluid volumes down to  1 / 5  the volume of the mixing bag. For example, a tank assembly  178  having a chamber with a volume of 100 liters would typically receive a mixing bag having a compartment with a volume of 100 liters. In turn, such an arrangement could be used to efficiently mix a volume of solution ranging from about 20 liters to about 100 liters.  
     [0170] Mixing bag  202  is inserted into the chamber of tank assembly  178  by being lowered through the top opening thereof. This can be accomplished either manually or through the use of lift  400 . If desired, feeding port  222  (FIG. 10A) can be secured to support rack  436  (FIG. 20) mounted on top of tank assembly  178 . For small mixing bags, however, the mixing bag need not be supported within the tank assembly.  
     [0171] The inflation of mixing bag  202  is in part helpful for the proper positioning of mixing bag  202  within the tank assembly, for accessing and connecting various structures to the top of mixing bag  202 , and, as will be discussed below in greater detail, for creating a positive gas pressure that helps the dry material component to feed into mixing bag  202 . It is not necessary, however, especially for small mixing bags, to inflate the mixing bag. Furthermore, for small mixing bags, air tube  432  (FIG. 1) can be eliminated and the mixing bag inflated solely through air inlet line  444  (FIG. 20).  
     [0172] IV. Feed Bag.  
     [0173] Depicted in FIG. 20, coupled with mixing bag  202  is a feed bag  450 . Feed bag  450  comprises a body  452  that extends from an upper end  451  to a lower end  453 . Body  452  has an interior surface  448  bounding a compartment  449 . Compartment  449  is at least partially filled with a feed component which is typically in the form of a powder, grain, or other substantially dry material that is flowable. The feed component can also be in a liquid form. Although the feed component can be any desired material, in one embodiment the feed component comprises culture media, buffers, or reagents in a powder form.  
     [0174] Lower end  453  of body  452  tapers down to a tubular spout  454 . Tubular spout  454  bounds an outlet  455  that is selectively and removably coupled with tubular coupling  243 . (Tubular coupling  243  was previously discussed with regard to Figure 10A.) This connection enables the feed component to pass from feed bag  450  to mixing bag  202  and can be secured through the use of a tie, band, clamp or the like. A removable clamp  456  is clamped across spout  454  to prevent unwanted passage of the feed component through spout  454 .  
     [0175] Feed bag  450  further comprises a handle  455  that is positioned at upper end  451  of body  452  for supporting feed bag  450 . Formed on upper end  451  of body  452  so as to communicate with compartment  449  is a fluid port  457  and a spaced apart vent port  459 . In one embodiment, ports  457  and  459  comprise conventional barbed ports outwardly projection from body  452 . Other conventional types of ports can also be used. Coupled with ports  457  and  459  is a fluid tube  458  and a vent tube  462 , respectively. Furthermore, a clamp  461 , such as a conventional hose clamp, is positioned on each of tubes  458  and  462 .  
     [0176] Fluid tube  458  is selectively and removably coupled with a delivery line  460  which communicates with a fluid source for delivering a rinsing fluid, such as water, into compartment  449 . Vent tube  462  is coupled with a filter  464 . Filter  464  can be mounted directly on vent port  459  or at any point along vent tube  462 . Filter  464  allows air and/or other gases to enter and/or escape from compartment  449  while preventing the escape of the feed component therethrough. In alternative embodiments, it is appreciated that feed bag  450  can be formed with a single port which can be used for either or both of the above functions.  
     [0177] Body  452  of feed bag  450  can be made of the same materials, such as polyethylene, and layers as previously discussed with regard to body  203  of mixing bag  202 . Furthermore, body  452  and thus feed bag  450  can be any desired shape or configuration and can be either a two or three dimensional bag. It is also appreciated that feed bag  450  can be any form of collapsible container or a rigid reusable container.  
     [0178] Returning to FIG. 1, lift  400  further includes an L-shape support  466  having a connector  468  mounted on the end thereof. Support  466  is selectively rotatable about the longitudinal axis of arm  404  to facilitate connecting connector  468  to handle  455  of feed bag  450 . Feed bag  450  is secured to connector  468  so as to suspend therefrom. Support  466  can also be configured to weigh feed bag  450  when connected thereto.  
     [0179] Although not required, in one embodiment a regulator  470  is mounted to arm  404  for selectively dispensing the feed component from feed bag  450 . As depicted in FIG. 21A, regulator  470  comprises a base frame  472  having a central channel  474  formed thereon. Tubular spout  454  of feed bag  450  is positioned so as to pass through channel  474 . A control plate  476  is slidably mounted to base frame  472  and is controlled by a push rod  475  to selectively slide within channel  474 . Mounted on control plate  476  is a vibrator  478 . During operation, control plate  476 , operable under electrical control of push rod  475 , is advanced within channel  474  so as to compress tubular spout  454  against base frame  472 , thereby preventing the unwanted passage of the feed component therethrough.  
     [0180] For controlled dispensing of the feed component, control plate  476  is retracted an incremental amount, thereby allowing the feed component to flow through the now only partially constricted tubular spout  454 . To help facilitate the passage of the feed component through tubular spout  454 , vibrator  478  can be activated which vibrates the feed component and assists it in passing through tubular spout  454 , coupling  243 , extension sleeve  239  and into compartment  220 . Dispensing of the feed component can be determined through the change of weight of feed bag  450  as measured by support  466 . It is appreciated that regulator  470  may or may not be required when all of the contents of feed bag  450  is to be dispensed within mixing bag  202 .  
     [0181] In one method of use as depicted in FIG. 20, once mixing bag  202  is inflated, air tube  432  (FIG. 1) is sealed closed and clamps  244  are removed from association with fluid port  224  and pressure port  226 . Compartment  220  of mixing bag  202  is now at least partially filled with a liquid component entering through fluid line  440  and fluid port  224 . In one embodiment, mixing bag  202  is initially filled with the liquid component to an amount between about 50% to 80% by volume. As the liquid component enters compartment  220 , the air within compartment  220  bleeds out through pressure port  226  so that the pressure range is maintained within compartment  220 . Either before, during, or after initial fluid filing of compartment  220 , feed bag  450  is coupled with mixing bag  202  as discussed above.  
     [0182] Once mixing bag  202  is filled with the liquid component to the initial capacity, clamps  245  and  456  are removed such that the feed component is free to feed into compartment  202  from feed bag  450 . The feed component can be fed as a dump or regulated through the use of regulator  470  as previously discussed. In alternative embodiments, the feed component can be feed into compartment  202  at any time during the process.  
     [0183] It has been discovered that the free and continuous flow of the powdered feed component from body  452  of feed bag  450  through tubular spout  454  and extension sleeve  239  is improved if feed bag  450  is operated under a positive air pressure. For example, the powdered feed component has improved flow properties if feed bag  450  is at least partially inflated by air flowing from mixing bag  202  up through extension sleeve  239  and tubular spout  454 . As such, pressure regulator  442  maintains the air pressure within compartment  220  of mixing bag  202  so that when clamps  245  and  456  are removed, feed bag  450  is subject to a positive air pressure. That is, air or other gases can be added or removed from mixing bag  202  through air inlet line  444  and air outlet line  446 , respectively, which are controlled by pressure regulator  442 .  
     [0184] Maintaining mixing bag  202  under a positive gas pressure also helps to ensure that unwanted gases or particulates do not unintentionally enter mixing bag  202  and contaminate the solution. In one embodiment, pressure regulator  442  maintains a positive pressure within compartment  220  in a range between about 0.5 KPa to about 14 KPa with about 3.5 KPa to about 10 KPa being more common. Other pressures can also be used depending on the system parameters.  
     [0185] Once feed bag  452  is empty, clamp  461  on fluid tube  458  is opened and a rinsing fluid, such as water or other compatible liquids for the solution, is fed through line  460  and fluid tube  458  into feed bag  450 . The rinsing fluid is used to help flush suspended particles and other residue of the feed component within feed bag  450 , coupling  243 , and extension sleeve  239  into compartment  220 . Once feed bag  452  is empty and flushed, clamp  461  is closed and line  460  disconnected. Furthermore, clamps  244  and  456  are closed about extension sleeve  239  and spout  454 , respectively. In this configuration, feed bag  450  remains inflated through air delivered from mixing bag  202 .  
     [0186] To deflate feed bag  450 , clamp  463  is opened on vent tube  462 . The venting air passes through filter  464  so as to capture any residue feed component. Vent tube  462  is also used to deflate feed bags  450  which are only partially emptied of the feed component. Feed bag  450  is uncoupled from coupling  243  either before or after deflating. If required, a new feed bag  450  can then be connected to coupling  243 . It is appreciated that in some embodiments it may be necessary to empty several feed bags  450  into mixing bag  202  for the production of the solution while in other embodiments it may be necessary only to empty a portion of a single feed bag  450 .  
     [0187] In some methods of use, vent tube  462  can remain open during dispensing of the feed component so that air continually passes out therethrough. Furthermore, in embodiments where mixing bag  202  is not under a positive pressure, vent tube  462  can be opened to allow filtered air to freely pass into mixing bag  202  to enhance the free flow of the feed component. Air or other gases can also be forced through vent tube  462  into feed bag  450 .  
     [0188] Depicted in FIG. 22 is an alternative embodiment of a feed bag  562 . Like elements between feed bag  562  and feed bag  450  are identified by like reference characters. In contrast to feed bag  450  where spout  454  removably connects with coupling  243 , spout  454  of feed bag  562  is welded or otherwise fixed to an outlet port  561 . As shown in FIG. 23, outlet port  561  has a diamond shaped base  563  having a plurality of ribs  564  extending along the length thereof. A tubular stem  565  is integrally formed with and extends through base  563 . Stem  565  bounds an opening  566  extending therethrough and terminates at an outwardly projecting flange  567 .  
     [0189] Base  563  of outlet port  561  is received within outlet  455  of body  452  so that the sides of spout  454  cover ribs  564 . A conventional welding technique, such as heat or sonic welding, is then used to weld the sides of spout  454  to ribs  564  so as to form a sealed connection therebetween. As desired, a clamp  568  is then used to removably and directly connect outlet port  561  of feed bag  562  to feed port  222  of mixing bag  202 .  
     [0190] Feed bag  562  is also distinguished from feed bag  450  in that a single port  570  is formed at upper end  451 . A transition tube  572  extends between port  570  and a three-way valve  574 . Fluid tube  458  and vent tube  462 , as previously discussed, are each coupled with valve  574 . Operating valve  574  thus enables fluid tube  458  and vent tube  462  to selectively communicate with compartment  449  of feed bag  562 .  
     [0191] V. Spray Nozzle.  
     [0192] Either subsequent to and/or concurrently with dispensing of the feed component into mixing bag  202 , the remainder of the required fluid component is fed into mixing bag  202  through fluid port  224  (FIG. 20). Although not required, in one embodiment, as depicted in FIG. 24, a spray nozzle  413  is removably mounted to fluid port  224 . As depicted by arrows  415 , spray nozzle  413  facilitates a radial outward spraying of the liquid component entering compartment  220  of mixing bag  202  through fluid port  224 . The sprayed liquid component helps wash down feed component that may have collected on the side walls of mixing bag  202  and also helps remove particles of the feed component suspended or floating within mixing bag  202 .  
     [0193] As depicted in FIGS. 25 and 26, spray nozzle  413  comprises a tubular body  414  having an exterior surface  415  and an interior surface  416  each extending between a first end  417  and an opposing second end  418 . Encircling and radially outwardly projecting from exterior surface  415  at first end  417  is a stepped flanged  409 . Interior surface  416  bounds a channel  419  that radially inwardly slopes at second end  418  to an end wall  421 . Extending between interior surface  416  and exterior surface  415  so as to encircle at least a portion of second end  418  is a helical slot  411 .  
     [0194] Returning to FIG. 24, during use second end  418  of spray nozzle  413  is passed through fluid port  224  so that stepped flange  409  engages with the leading edge of fluid port  224 . In this configuration, second end  418  having helical slot  411  formed thereon is disposed within compartment  220  of mixing bag  202 . The fluid component flowing down extension tube  249  enters channel  419  of spray nozzle  413  at first end  417 . The fluid component travels down channel  419  and is radially outwardly sprayed through helical slot  411 . In turn, the sprayed fluid component functions to wash down the feed component as previously discussed. In alternative embodiments, it is appreciated that spray nozzle  413  or the end thereof can be replaced with any number of different spray heads such as those used in conventional sprinkler systems.  
     [0195] VI. Mixing and Removal of Solution.  
     [0196] During and/or subsequent to feeding of the components into compartment  220  of mixing bag  202 , mixer  204  or one of the alternatives thereto is activated so as to mix the components into a homogeneous solution. Specifically, as previously discussed, mixer  204  is repeatedly raised and lowered within compartment  220  under various operating parameters specific to the volume and type of solution being made. One of the benefits of mixers  204 ,  310 , and  374  is that they are able to efficiently mix both large and relatively small amounts of solution with minimal shearing forces and while minimizing the formation of foam. High shearing forces and the formation of foam can be detrimental to some biological solutions.  
     [0197] Although side wall  24  of tank assembly  20  can be any configuration, such as circular as shown in FIG. 2, it has been discovered that improved mixing properties are obtained if the interior configuration of the side wall has a polygonal configuration, such as the hexagonal configuration shown in FIG. 7. The polygonal configuration appears to increase turbulent flow which improves mixing.  
     [0198] As the feed component and the liquid component are mixed within compartment  220 , samples can be drawn out and tested through sample tube  428  in communication with delivery tube  420  as depicted in FIG. 1. Likewise, select additives can be added through sample tube  428  which additives then pass through pump  424  and then back into compartment  220  through return tube  430 . Examples of additives include serum, acids, bases, lipids, buffers, and trace element components. Once the feed component and liquid component are mixed to a desired amount, typically to a homogenous solution, the solution can be directly dispensed through delivery tube  420 , passed through filtration system  500  (as discussed blow), or passed through some other type of system prior to dispensing.  
     [0199] In the embodiment where upper end  214  of mixing bag  202  is secured to support rack  436  by clamp  438  as shown in FIG. 20, mixing bag  202  remains suspended within chamber  60  as the solution is removed from mixing bag  202 . In one embodiment, as the solution is removed, mixing bag  202  begins to radially inwardly collapse from upper end  214  to lower end  216 . Accordingly, when all of the solution is removed, mixing bag  202  is almost entirely supported by support rack  436 . In an alternative embodiment, as the solution is removed, air or some other gas in continually pumped into compartment  220  through air inlet line  444  so as to maintain a positive pressure within mixing bag  202 . Mixing bag  202  thus remains partially supported by the side wall of the tank assembly. Inflating mixing bag  202  also helps in removal of all solution therefrom.  
     [0200] Once all of the solution is removed, mixing bag  202  can be refilled for a new batch. Alternatively, mixing bag  202  is disconnected from the various tubes and mixing shaft  208  is disconnected from actuation rod  172 . The entire mixing assembly  200  is then removed from chamber  60  through the use of lift  400  where it is then either disposed of or recycled. A new mixing assembly can then be inserted within chamber  60  for the production of a new batch of solution without the need to sterilize or clean tank assembly  20 .  
     [0201] VII. Temperature Probe.  
     [0202] As previously discussed, fluid channels  44  in side wall  24  of tank assembly  20  are used for controlling the temperature of the solution within mixing bag  202 . Although fluid channels  44  can regulate temperature, they do not actually measure the temperature of the solution. In one embodiment, conventional temperature probes can be inserted into the solution through ports on mixing bag  202 . One downside to this embodiment, however, is that the probes must then be sterilized prior to use with a different batch or type of solution.  
     [0203] Accordingly, in one embodiment of the present invention means are provided for continuously sensing the temperature of the solution within compartment  220  of mixing bag  202  without directly contacting the solution. By way of example and not by limitation, depicted in FIG. 27 is a temperature probe  480  having an exterior surface  481  extending between a first end  482  and an opposing second end  483 . Outwardly projecting from exterior surface  481  between opposing ends  482  and  483  is a mounting flange  484 . First end  482  terminates at a substantially flat end face  485 . Projecting from second end  443  is signal wiring  486  for transmitting the signal produced by temperature probe  480 .  
     [0204] Depicted in FIG. 28, temperature probe  480  is further defined as having a cylindrical housing  488  comprising an encircling peripheral wall  489  and an end wall  490  disposed at first end  482  thereof. Housing  488  is typically comprised of metal, such as stainless steel, and typically has a thickness in a range between about 0.3 mm to about 3 mm. Other materials and thicknesses can also be used. Housing  488  has an interior surface  491  which bounds a cavity  492 . Disposed within cavity  492  so as to bias against interior surface  491  of end wall  490  is a thermal sensor  494 . In one embodiment thermal sensor  494  comprises a thermal resistor or other configurations of thermal sensitive material, such as in the form of wiring, wherein the electrical resistance of the material changes as the temperature of the material changes. Accordingly, by passing an electrical current through the thermal resistor or other material and measuring the resistance, the temperature at thermal sensor  494  can be measured.  
     [0205] In the embodiment depicted, thermal sensor  494  comprises the wiring out of a conventional linear RTD (resistance thermal device) probe. As depicted in FIG. 29, the linear wiring has been coiled into a substantially flat circular configuration. In one embodiment, sensing element  494  is comprised of platinum but can also be comprised of nickel, copper, nickel-iron or other thermal resistance materials. Extending from thermal sensor  494  within cavity  492  is signal wiring  486 . Signal wiring  486  is used for passing a current through thermal sensor  494 . The remainder of cavity  492  is filled with an insulative plug  496  which surrounds signal wiring  486 . In one embodiment, insulative plug  496  is comprised of a ceramic such as aluminum oxide (alumina). Other types of insulation can also be used. The above configuration of thermal sensor  494  and the positioning of insulative plug  496  focuses the temperature sensing path of thermal sensor  494  toward end wall  490 .  
     [0206] In one embodiment, as depicted in FIG. 30, to facilitate use of temperature probe  480  a hole  497  is formed through base floor  112  of floor  110 . A tubular collar  498  is mounted, such as by welding, to the bottom surface of base floor  112  so as to encircle hole  497 . A flange  499  outwardly projects from the free end of collar  498 . First end  482  of temperature probe  480  is advanced through tubular collar  498  so that mounting flange  484  of temperature probe  480  biases against flange  499 . A clamp  493 , such as a hinged tri-clamp or any other type of clamp, is then used to removably secure flanges  484  and  499  together. In this secure but removable configuration, at least a portion of first end  482  of temperature probe  480  projects past the interior surface of base floor  112  and into chamber  60 .  
     [0207] In one embodiment, end face  485  is spaced apart from the interior surface of base floor  112  by a distance in a range between about 1 mm to about  5  mm. Other distances can also be used. In this configuration, mixing bag  202  biases directly against end face  485  of temperature probe  480 . This biasing force increases as mixing bag  202  is filled with the solution.  
     [0208] During operation, temperature probe  480  measures the surface temperature of mixing bag  202 , and thus the temperature of the solution therein, without penetrating mixing bag  202  or being in direct contact with the solution. As such, there is no need to sterilize or clean temperature probe  480  as fluid preparation system  10  switches between the manufacture of different batches or types of solution. To accurately determine the temperature of the solution, the sensed temperature is calibrated to offset the thermal lag of mixing bag  202 . Accuracy of the measured temperature depends in part on end face  485  of temperature probe  480  being clean and being in intimate contact with mixing bag  202 . In the depicted embodiment, temperature probe  480  is mounted on base floor  112  so as to utilize the weight of the solution in maintaining intimate contact between temperature probe  480  and mixing bag  202  throughout the process.  
     [0209] In alternative embodiments, it is appreciated that end face  485  of temperature probe  480  can be positioned flush with or below the interior surface of base floor  112 . Furthermore, temperature probe  480  can be mounted on other portions of floor  102  or on side wall  24 . It is also appreciated that temperature probe  480  can be mounted in any number of fixed or removable manners to tank assembly  20 .  
     [0210] VIII. Filtration System.  
     [0211] As depicted in FIG. 31, filtration system  500  comprises a valve  502  which splits delivery tube  420  into a first leg  504  and a discrete second leg  506 . As previously discussed, valve  502  can simply comprise a tee joint coupled with delivery tube  420  and legs  504  and  506  acting in combination with external clamps which selectively close around either first leg  504  and/or second leg  506 . Alternatively, there are a variety of other conventional types of electrical and manual valves that can be used.  
     [0212] Coupled with each leg  504  and  506  is a pressure sensor  508  and one or more filters  510 . The type and number of filters  510  depends upon the material being processed and the desired properties of the end product. In one embodiment, filters  510  can comprise conventional bacterial filters to facilitate sterilization of the solution. Once the solution passes through filters  510 , legs  504  and  506  connect together as a valve  511  to reestablish delivery tube  420 . The solution then again passes by or through a pressure sensor  512  and then through a final filter  514 .  
     [0213] During operation, valves  502  and  511  are set so that the solution passes through only one of legs  504  or  506 . For example, valves  502  and  511  can initially be set so that the solution entering from delivery tube  420  passes through first leg  504 . As filters  510   a  become partially occluded by filtered material, the fluid back pressure is sensed by pressure sensor  508   a . When filters  510   a  are sufficiently occluded as determined by a preset back pressure, valves  502  and  511  are switched so that the fluid passes through leg  506 . Filters  510   a  are then replaced with clean filters. When filters  510   b  become occluded the process is repeated. Accordingly, by using this configuration of filtration system  500 , filtration of the solution can be continuous.  
     [0214] Pressure sensor  512  is either directly or indirectly coupled with pump  424  (FIG. 1) so as to control the flow rate of solution through delivery tube  420 . That is, as the pressure drops at pressure sensor  512  due to the increased occlusion of filters  510   a  or  510   b , the speed of pump  424  can be increased so that the flow rate of solution is relatively constant. Likewise, when filtration system  500  switches to new filters causing the pressure to increase, pump  424  can be slowed. Where it is not desired to have a constant flow rate, pressure sensor  512  is not required.  
     [0215] As will be discussed below with regard to dispenser assembly  700 , filter  514  is used for final sterilization of the solution and can be considered either part of filtration system  500  or dispenser assembly  700 .  
     [0216] In alternative embodiments, it is appreciated that filtration system  500  can comprise three or more discrete legs. Alternatively, filtration system  500  need not include two or more separate legs but can simply comprise a pressure sensor and one or more filters through which deliver tube  420  passes. In this embodiment, however, it is necessary to stop the filtration process to replace the filters. In yet other embodiments, pressure sensor(s)  508  are not required. In theses embodiments, filters  510  can simply be replaced after predetermined periods of use.  
     [0217] IX. Pressure Sensor Assembly.  
     [0218] The various pressure sensors  508  and  512  depicted in FIG. 31 can comprise any conventional pressure sensor which is placed in direct communication with the solution so as to measure the fluid pressure thereof. In an alternative embodiment, however, pressure sensors can be positioned so that they are not in direct fluid communication with the solution. As a result, it is not necessary to sterilize or clean the pressure sensors as fluid preparation system  10  is switched between the manufacture of different batches or types of solution.  
     [0219] By way of example and not by limitation, depicted in FIG. 32 is one embodiment of a pressure sensor assembly  516 . Assembly  516  comprises a pressure sensor  517 , a diaphragm  518 , a sensing port  519 , and a clamp  521 . Sensing port  519  comprises a tubular stem  520  projecting from delivery tube  420 . Stem  520  bounds a passageway  523  that communicates with delivery tube  420 . Encircling and radially outwardly projecting from the free end of stem  520  is a flange  524 . Flange  524  terminates at an engagement face  526 . A continuous sealing groove  528  is recessed on engagement face  526  so as to encircle passageway  523 .  
     [0220] As depicted in FIGS. 32 and 33, diaphragm  518  has a first side  530  and an opposing second side  532 . A sealing ridge  534  and  536  outwardly projects in a continuous loop from first side  530  and second side  532 , respectively. Recessed into second side  532  within the area bounded by sealing ridge  536  is a pocket  538 . Diaphragm  518  is removably seated on engagement face  526  of sensing port  519  so that sealing ridge  536  is received within sealing groove  528 . In this configuration, diaphragm  518  covers the opening to passageway  523  with pocket  528  being aligned therewith.  
     [0221] Pressure sensor  517  is a standard “off-the-shelf” item such as a conventional digital or analog pressure transducer. One example of pressure sensor  517  comprises the Mini Pressure Transducer produced by Anderson Instrument Co. out of Fultonville, N.Y. As depicted, pressure sensor  517  comprises a body  540  having a tubular stem  542  projecting therefrom. Encircling and outwardly projecting from the free end of stem  542  is a flange  544 . An engagement face  546  is formed on one side of flange  544 . Engagement face  546  encircles an opening  548  in which a sensor  550  is movably disposed. A continuous sealing groove  552  is recessed on engagement face  546  so as to encircle opening  548 .  
     [0222] Engagement face  546  is received on first side  530  of diaphragm  518  so that sealing ridge  534  is received within sealing groove  552 . In this configuration sensor  550  is based against first side  530  of diaphragm  518  opposite of pocket  538 .  
     [0223] Clamp  521  is used to secure flanges  524  and  544  together so that diaphragm  518  seals against sensing port  519  and so that sensor  550  is held against diaphragm  518 . The seal prevents solution passing through delivery tube  420  and entering passageway  523  from leaking out between flange  524  and diaphragm  518 . In one embodiment, clamp  521  comprise a conventional hinged tri-clamp such as available from Tri-Clover out of Kenosha, Wis. Alternatively, any other type of removable clamp or securing structure can be used that produces the desired coupling.  
     [0224] During operation, the solution passing through delivery tube  420  enters passageway  523  of sensing port  519  and pushes against diaphragm  518 . In turn, diaphragm  518  pushes against sensor  550 . Pocket  538  is formed so as to decrease the thickness of diaphragm  518  at that location, thereby increasing the pressure sensitivity thereat. Readings or signals from sensor  550  are used to determine the actual or relative fluid pressure of the solution.  
     [0225] Because the solution does not directly contact clamp  521  or pressure sensor  517 , these components do not have to be sterilized or otherwise cleaned when fluid preparation system  10  is switched between the manufacture of different batches or types of solution. The remainder of pressure sensor assembly  516 , namely, diaphragm  518  and sensing port  519 , are relatively inexpensive and can simply be replaced during the manufacture of different solutions.  
     [0226] Diaphragm  518  is typically molded, such as by compression or injection molding, from a soft flexible material. Examples of materials that can be used include neoprene, silicone, EPDM, Viton, Kalrez, Teflon, polypropylene, polyethylene, polyolefin, Buna, and nitrile rubber as well as other moldable plastic compounds. The above materials can also be reinforced with glass, carbon, or other types of fibers. The portion of diaphragm  518  that pushes against sensor  550  typically has a thickness in a range between 2 mm to about 20 mm with about 3 mm to about 10 mm being more common.  
     [0227] Depicted in FIGS. 34 and 35 are alternative embodiments of diaphragm  518  wherein like elements are identified by like reference characters. Depicted in FIG. 34 is a diaphragm  554  wherein a central sensing portion  556 , i.e., the area bounded by sealing ridges  534  and  536 , has a substantially uniform thickness. This thickness can be any desired amount to produce the desired sensitivity. Depicted in FIG. 35 is a diaphragm  558  wherein a central sensing portion  560  tapers on each side from sealing ridges  534  and  536  to a central flat portion  562 . In yet other embodiments, one side of central sealing portion  560  can be flat as shown with diaphragm  554  while the other side is tapered as shown with diaphragm  558 . Other combinations and alternative configurations can also be used.  
     [0228] X. Dispensing System.  
     [0229] Once the solution passes through filtration system  500 , the solution is dispensed either directly into its end use environment or into a container. When it is not necessary that the solution be sterile, the solution can simply be dispensed from delivery tube  420  in any conventional manner. Where the solution must remain sterile after passing through the filters, it is necessary that a sterile fluid coupling be formed between delivery tube  420  and the end storage container.  
     [0230] By way of example and not by limitation, depicted in FIG. 36 is one embodiment of a sterile fluid dispensing system  700 . Dispensing system  700  comprises a delivery assembly  702 , a collector assembly  704 , and a sterilizer  706 . Delivery assembly  702  comprises filter  514 , a flexible extension tube  712 , and a rigid fill tube  714 . Filter  514  is a final sterilizing filter which is designed so that all solution passing therethrough is completely sterile or is at least filtered to the desired parameters of the end product solution. As such, the solution prior to filter  514  need not be sterile. Filter  514  has an inlet port  708  and an outlet port  710 . Inlet port  708  is configured to selectively and removeably couple with delivery tube  420  while outlet port  710  is coupled in sealed fluid communication with a first end  711  of extension tube  712 .  
     [0231] Fill tube  714  is coupled in sealed fluid communication with a second end  713  of extension tube  712 . Depicted in FIG. 37, fill tube  714  comprises a tubular, cylindrical body  715  having an interior surface  716  and an exterior surface  718  each extending between a first end  720  and an opposing second end  722 . Interior surface  716  bounds a channel  724  longitudinally extending through fill tube  714 . Encircling and radially outwardly projecting from first end  720  of body  715  is a flange  728 . Projecting from first end  720  of body  715  in longitudinal alignment therewith is a barbed port  717 . Barbed port  717  is received within second end  713  of extension tube  712  so as to affect a sealed fluid communication therewith. In alternative embodiments, any conventional form of connection can be used to fluid couple fill tube  714  to extension tube  712 .  
     [0232] Formed at second end  722  of body  715  is a tapered, substantially frustaconical nose  730 . Nose  730  bounds an outlet  732  in fluid communication with channel  724 . A locking groove  734  encircles and is recessed into exterior surface  718  of nose  730 . As depicted in FIGS. 37 and 38, mounted within outlet  732  and secured to interior surface  716  of nose  70  are a pair of crossing puncture blades  736 . Each blade  736  has a sharpened outer edge  738  that projects beyond the end of nose  730   
     [0233] As depicted in FIGS. 37 and 39, a cap  740  is removeably mounted on second end  722  of fill tube  714  so as to seal off outlet  732 . Cap  740  has an annular substantially frustaconical side wall  742  that terminates at a end plate  744 . Side wall  742  has an interior surface  746  and an exterior surface  748  that each extend between a first end  750  and an opposing second end  752 . Radially inwardly projecting from interior surface  746  at first end  750  is an annular locking ridge  754 . Encircling and radially outwardly projecting fromr exterior surface  748  at second end  752  is a barb  756 . As depicted in FIG. 37, cap  740  is received over nose  730  so that locking ridge  754  of cap  740  is received within locking groove  734 , thereby forming a sealed connection between cap  740  and fill tube  714 . In one embodiment, fill tube  714  is made of a metal, such as stainless steel, while cap  740  is formed of a molded plastic. In other embodiment, fill tube  714  can also be made of rigid plastics, composites, or other materials.  
     [0234] In its fully assembled state, as depicted in FIG. 36, delivery system  702  is sterilized as a unit such as by ionizing radiation or other conventional sterilization techniques.  
     [0235] Collector assembly  704  as shown in FIG. 36 comprises a flexible extension tube  760  having a first end  762  and an opposing second end  764 . Second end  764  of extension tube  760  is coupled in sealed fluid communication with a container  765 . Container  765  can comprise any rigid or flexible container used for holding sterile fluids. Container  765  can be disposable or recyclable. For example, in one embodiment container  765  comprises a bag made of the same materials and methods as previously discussed with regard to mixing bag  202 .  
     [0236] Mounted at first end  762  of extension tube  760  is a fill port  766 . As depicted in FIG. 40, fill port  766  comprises a tubular, substantially cylindrical body  767  having an interior surface  768  and an exterior surface  770  each extending between a first end  772  and an opposing second end  774 . Interior surface  768  bounds a channel  776  longitudinally extending through fill port  766 . Encircling and outwardly projecting from exterior surface  770  at first end  772  is an annular flange  778 . Encircling and outwardly projecting from exterior surface  770  at second end  774  is an annular barb  780 . Second end  774  of fill port  766  is received in sealed fluid communication within first end  762  of extension tube  760 . In other embodiments, other conventional connections can be used to couple fill port  766  with extension tube  760 . For example, rather than using barb  780 , fill port  766  can be heat sealed, welded, or otherwise secured to extension tube  760 .  
     [0237] Fill port  766  terminates at an end face  781  at first end  772 . Interior surface  768  of fill port  766  includes a sloping, substantially frustaconical seat  782  extending from end face  781 . Seat  782  bounds an opening  784  to channel  776 . Mounted on end face  781  so as to extend across opening  784  is a membrane  786 . In this configuration, membrane  786  seals opening  784  closed. Membrane  786  is typically made of a sheet of polymeric material that can be selectively punctured.  
     [0238] In its fully assembled state, as depicted in FIG. 36, collector assembly  704  is completely sealed. In this configuration, collector assembly  704  is sterilized such as by ionizing radiation or other conventional techniques of sterilization.  
     [0239] Depicted in FIG. 41 is one embodiment of two adjacently disposed sterilizers  706 , one of such sterilizers being shown in a partially disassembled state. Mounted on each sterilizer  706  is an automated hose clamp  757 . Hose clamp  757  comprises a rack  758  on which a flexible hose or tube is selectively placed. A piston  761  selectively raises and lowers an arm  759  projecting therefrom. When arm  759  is in the lowered position, arm  759  biases against the hose so as to pinch the hose closed. As arm  759  is raised, fluid is allowed to flow through the hose.  
     [0240] As depicted in FIG. 42, sterilizer  706  comprises a housing  790  having a front face  792  extending between opposing side faces  794  and  796 . Also extending between side faces  794  and  796  is a top face  798 . As depicted in FIG. 43, a cavity  808  is formed within housing  790 . Projecting from each side face  794  and  796  so as to be in alignment with cavity  808  is an electron beam generator  800 . Each generator  800  communicates with cavity  808  through a corresponding channel formed on housing  790 . Although not required, in the embodiment depicted, generators  800  are disposed at an angle α in a range between about 15° to about 45° relative to the horizontal. One example of an electron beam generator is the E-Beam module available from USHIO America out of Cyprus, Calif.  
     [0241] Each electron beam generator  800  generates an electron field within cavity  808  so as to sterilize cavity  808  and all structure placed therein. During operation of generators  800 , cavity  808  is continually flooded with a non-oxidizing gas, such as nitrogen. The non-oxidizing gas displaces any oxygen from within cavity  808 . Subjecting oxygen to the electron field could convert the oxygen to ozone which could produce a corrosive effect. To prevent the surrounding environment from being exposed to the electron field, housing  79  is formed of stainless steel or other shielding materials in sufficient thickness to block any harmful emission of the electron field.  
     [0242] Mounted on top face  798  of housing  790  is a plunger  802  which operates a tubular piston  804 . Tubular piston  804  bounds a passageway  806  (FIG. 42) that communicates with cavity  808 . As depicted in FIG. 43, piston  804  is configured to receive fill tube  714  within passageway  806  so that flange  728  of fill tube  714  rests on piston  804 . In this configuration, second end  722  of fill tube  714  is received within cavity  808 . As will be discussed below in greater detail, plunger  802  and piston  804  are configured to securely retain fill tube  714  when disposed therein and to selectively raise and lower fill tube  714 .  
     [0243] Returning to FIG. 42, slidably mounted so as to selectively extend into and out of housing  790  through front face  792  is a shuttle assembly  816 . Shuttle assembly  816  comprises a female shuttle  818  and a male shuttle  820 . Female shuttle  818  has opposing side faces  822  and  824  with a front face  826  and a top face  828  each extending therebetween. Front face  826  has a sloping step shaped configuration. Specifically, front face  826  has a substantially vertical upper portion  830 , a substantially vertically lower portion  832 , and an outwardly sloping central portion  834  extending therebetween. Recessed into and extending along the length of front face  826  so as to have substantially the same sloping configuration as front face  826  is an open channel  836 .  
     [0244] Mounted flush on top face  828  at the intersection with front face  826  is a substantially U-shaped retaining collar  840 . Collar  840  has an interior face  842  with a substantially U-shaped groove  844  recessed thereon.  
     [0245] Male shuttle  820  has a front face  848 . As discussed and depicted below in greater detail, front face  848  of male shuttle  820  is configured to complementarily mate in close tolerance with front face  826  of female shuttle  818  while leaving channel  836  open. In general, shuttles  818  and  820  are operable between one of three positions. In a first position as depicted in FIG. 42, front face  848  of male shuttle  820  is separated from front face  826  of female shuttle  818  with both front faces  826  and  848  being disposed outside of housing  790 . In a second position, male shuttle  820  is moved to mate with female shuttle  818 . In the third position, as depicted in FIG. 45, mated shuttles  818  and  820  are moved into housing  790  such that retaining collar  840  is disposed in alignment with cavity  808 .  
     [0246] During use, fill tube  714  is slidably received within opening  806  of tubular piston  804  as previously discussed and depicted in FIG. 43. Once fill tube  714  is positioned, electron beam generators  800  are activated so that the electron field is generated within cavity  808 , thereby sterilizing second end  722  of fill tube  714 . Extension tube  712  of delivery assembly  702  (FIG. 36) is placed on rack  758  of hose clamp  757  (FIG. 41). Arm  759  is then lowered so as to temporarily close off extension tube  712 .  
     [0247] A cap remover  860  is removeably slid within groove  844  of retaining collar  840 . As depicted in FIG. 44, cap remover  860  has an interior surface  862  and an opposing exterior surface  864  each extending between a top end face  866  and a bottom end face  868 . Encircling and radially outwardly projecting from exterior surface  864  at top end face  866  is an annular flange  870 . Interior surface  862  bounds a channel  872  that extends through cap remover  860 . Interior surface  862  comprises cylindrical portion  876  that extends from bottom end face  868  and an inwardly sloping frustaconical tapered portion  878  that extends from top end face  866  to cylindrical portion  876 . In this configuration, cylindrical portion  876  has a diameter slightly smaller than the diameter of cap  740  at barb  756 .  
     [0248] Cap remover  860  is manually positioned within retainer collar  840  by sliding flange  870  into groove  844 . Once positioned, male shuttle  820  is mated with female shuttle  818  so as to lock cap remover  860  in place. The mated shuttles are then moved into housing  790 , as illustrated in FIGS. 45 and 46, so that cap remover  860  is vertically aligned and exposed to cavity  808 .  
     [0249] Next, as depicted in FIGS. 46 and 47, piston  804  drives fill tube  714  downward causing second end  752  of cap  740  to pass through cap remover  860 . Annular barb  756  is resiliently compressed as it passed through cylindrical portion  876  of the interior surface of cap remover  860 , but then radially outwardly expands as it passes bottom end face  868 . As a result, annular barb  756  rests against bottom end face  868 , thereby locking cap  740  in engagement with cap remover  860 .  
     [0250] As depicted in FIG. 48, piston  804  then moves fill tube  714  back to the raised position. As a result of the engagement between cap remover  860  and cap  740 , cap  740  is removed from fill tube  714  and retained on cap remover  860 . In this position, second end  722  of fill tube  714  is openly exposed within cavity  808  of housing  790 . Due to the electron field maintained within cavity  808 , however, second end  722  of fill tube  714  remains sterilized.  
     [0251] Once cap  740  is removed, shuttles  818  and  820  slide out of housing  790  and separate. Next, as depicted in FIG. 49, cap remover  860  is replaced in retaining collar  840  with fill port  766  of collector assembly  704  (FIG. 36). Extension tube  760  is positioned within channel  836 . Again, shuttles  818  and  820  are closed locking fill port  766  and extension tube  760  therebetween. As depicted in FIG. 50, the mated shuttles are then slid within housing  790  so that fill port  766  is vertically disposed below and in communication with cavity  808 . The exterior of fill port  766  is thus sterilized through exposed to the electron field.  
     [0252] Once fill port  766  is positioned, fill tube  714  is again lowered. In so doing, as shown in FIG. 51, blades  736  of fill tube  714  puncture membrane  786 . Once membrane  786  is punctured, nose  730  of fill tube  714  engages against seat  782 , thereby forming a fluid coupling between fill tube  714  and fill port  766 . Again, it is appreciated that throughout the process the electron field is maintained within cavity  808  so that all parts therein are sterilized.  
     [0253] Once fill tube  714  is coupled with fill port  766 , clamp  757  (FIG. 41) is opened allowing the flow of solution through delivery assembly  702  and into collecting assembly  704 , thereby filling container  765 . As depicted in FIG. 1, in one embodiment a scale  882  is disposed below container  765 . Once container  765  has been filled to a desired weight or to other form of fill mark, clamp  757  is again closed, thereby closing off the flow of solution. A tube heat sealer  880 , which comprises two opposing heated elements as shown in FIG. 43, is then closed on opposing sides of extension tube  760 , thereby pinching and heat sealing extension tube  760  closed. Extension tube  760  is then either removed from the shuttles or cut above the seal so as to allow removal of container  765  containing the sterile solution.  
     [0254] Once a first container  765  is filled, the process can be repeated for a new collector assembly  704 . That is, fill tube  714  is raised within cavity  808  and shuttles  818  and  820  retracted. A new fill port  766  coupled with a new container  765  is then mounted with shuttles and shifted back into cavity  808  for filling by fill tube  714 .  
     [0255] Housing  790  and shuttles  818  and  820  are configured to shield the emission of the electron field outside of cavity  808 . However, channel  836  cannot be shielded closed in that extension tube  760  is disposed therein. The electrons entering cavity  808  travel in straight paths and dissipate once they encounter the shielding. Accordingly, to prevent the emission of electrons though channel  836 , channel  836  is curved in a step-like fashion as previously discussed. This curvature of channel  836  ensures that the electrons entering channel  836  contact the wall bounding channel  836  prior to exiting therethrough. In alternative embodiments, channel  836  can be curved, bent, or otherwise shielded or blocked in a variety of different configurations so as to prevent a straight path from cavity  808  to the exterior.  
     [0256] In the above described embodiment of sterilizer  706 , electron beam generators are used for sterilizing parts within or communicating with cavity  808 . In alternative embodiments, it is appreciated that other forms of radiation, such as ultra violet light, can also be used for sterilization. In yet other embodiments, thermal sterilization can be used such as by the use of steam. Finally, vapor phase sterilization can be used such as through the use of hydrogen peroxide or chlorine dioxide. Each of the above described options are examples of means for generating a sterilizing field with cavity  808 .  
     [0257] In one embodiment, once the solution is emptied from mixing bag  202 , all of the components that were in direct contact with the solution are simply removed and disposed of or recycled. For example, each of the structural components such as the mixing bag, feed bag, mixer, tubes, pressure sensor diaphragm, connectors, ports, filters, and delivery assembly are designed and manufactured so as to be considered disposable components. Once the old components are removed, they are replaced with clean components. The fluid preparation process can then be repeated for a new solution without the need for cleaning, sterilization, or the risk of cross contamination. Of course in alternative embodiments where the solution need not be sterile or pure, some or all of the components can be repeatedly used and then discarded when worn or when an incompatible solution is to be prepared.  
     [0258] In one embodiment it is desirable that each of the structural components that the solution contacts be made from the same resin family. For example, each of the above identified structural components and any others that directly contact the solution or feed component can be made of polyethylene. By having all of the structural components made from the same resin family, it is easier to control and monitor any effects resulting from leaching, adsorption, and absorption between the solution and the structural components. Depending on the solution being made, it can also be desirable that the structural components that contact the solution satisfy USP Class  6  testing for biological products and/or that they have no cytotoxic effects. In other embodiments, the different components can be made of different materials and need not satisfy the above testing.  
     [0259] XI. Conclusion.  
     [0260] It is appreciated from the forgoing that the inventive fluid preparation system  10  can, in various embodiments, include manually actuated components, electrically actuated components, and combinations thereof. In embodiments, where electrically actuated components are used, a central processing unit  890 , as shown in FIG. 1, is provided for controlling the components. Furthermore, central processing unit  890  can be loaded with select programs for automating select operations of the fluid preparation system  10 .  
     [0261] Fluid preparation system  10  and the structural components thereof provide a number of unique advantages over conventional fluid preparation systems. By way of example and not by limitation, the system enables a manufacturer or an end user to efficiently manufacture predefined amounts of a solution to meet a desired need, thereby avoiding short supply or the necessary storage of over supply. By using disposable components, the system can be used to rapidly make different batches or types of solutions without the costly delay or expense of having to clean or sterilize structural parts. The mixers enable efficient mixing of the solution while minimizing high shearing, foaming or splashing that could be potentially detrimental to some solutions. The feed bag enables efficient storage and dispensing of powder components while minimizing the possibility of potentially harmful components being emitted into the surrounding environment. Similarly, the final dispensing system provides an efficient way for quickly filling a number of different containers and switching between different solution batches while ensuring that the solution is sterile and sealed in a closed container.  
     [0262] Fluid preparation system  10  includes many discrete components, some of which are identified by section headings. It is appreciated that each of the disclosed components and alternatives thereof contain novel features and that each component can be used independently, in different assemblies of fluid preparation system  10 , or in systems other than fluid preparation systems. For example, it is appreciated that each of the various components can be mixed and matched depending on the type of solution to be made and whether or not the solution needs to be sterile. As such, different systems may have different benefits and be used in different ways.  
     [0263] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.