Patent Publication Number: US-2022228686-A1

Title: Compression Collars for Coupling a Tube to a Tube Fitting

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/863,031, filed Jan. 5, 2018, which claims the benefit of U.S. Provisional Application No. 62/442,889, filed Jan. 5, 2017, which are incorporated herein by specific reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to compression collars used for securing tubes to tube fittings and methods of use. 
     2. The Relevant Technology 
     Within the biopharmaceutical industry there exists many applications where various fluids are stored, mixed, processed, and transported to and from biological processing containers. Such fluids can be very expensive and it is typically critical that they be maintained in a sterile environment. To help maintain sterility and to eliminate the need for cleaning, most fluids are processed and stored in sterile polymeric bags. To facilitate transfer of fluid between different bags, polymeric tubing is connected to barbed ports secured to the bags. 
     One weakness with the traditional friction fit connection between the tubing and the barbed port is that when the fluid system is pressurized, the applied pressure can cause the tubing to separate or lift off of the face of the barb on the port. This separation can cause potential leaks and contamination of the fluid. Another problem exists when customers handle the fluid system and manipulate the barbed port connection. Such handling can again cause the sealed connection between the barbed port and the tubing to be broken, thereby risking contamination of the fluid. 
     To assist in eliminating the above problems, the biopharmaceutical industry has adopted the use of cable ties, also known as zip ties, which are manually secured around the tubing over each barbed port. The cable ties provide a compressive force on the tubing that produces a sealed engagement between the tubing and the port, even when the system is handled or pressurized. For example, a common cable tie is normally made of nylon and includes a locking head having an opening extending therethrough and an elongated, flexible tape section that projects from the locking head. Teeth are formed on the tape section. A pawl projects into the opening of the locking head and is configured to engage the teeth to form a ratchet. During use, the free end of the tape section is passed around a tube and pulled through the opening of the locking head to form a continuous loop. As the tape section is pulled further through the opening, the continuous loop constricts to produce a compressive force on the tube that the cable tie encircles. Concurrently, the pawl engages with the teeth so that the tape section can be freely pulled into the opening of the locking head but is prevented from being pulled out of the opening of the locking head, thereby holding the cable tie in the constricted state. 
     Although cable ties have been largely found to be effective, such use has its shortcomings. For example, once a cable tie is secured in place, the unused free end of the tape section is typically cut off. As a result of the cut, however, the remaining tape section now has sharp corners that can potentially puncture or otherwise damage the polymeric bags of the fluid system, especially when the polymeric bags are folded over the cable ties for transport or storage. Although bubble wrap or other packing can be placed over each cable tie, such a process is time consuming, labor intensive and subject to error or failure. 
     Furthermore, a cable tie does not provide a uniform compressive force around the tube to which it is secured. Rather, as a result of the geometry of the cable tie, there is a location at the intersection of where the tape section feeds into the locking head where a gap or at least decreased compressive force is typically formed between the cable tie and tubing. As a result, there is an area of weakness between the tube and barbed port that has a higher probability of leaking and permitting contamination of the fluid. Cable ties are also problematic in that they can be difficult to attach and difficult to control the amount of compressive force they apply. In part, this is because cable ties are narrow and thus only cover a small portion of the port. In addition, cable ties are tightened by a hand tool that can result in variance in tension between different cable ties. Furthermore, after a cable tie is tensioned, it will naturally relax over time, thereby decreasing compression on the port. Other problems also exist with using conventional cable ties. 
     Accordingly, what is needed in the art are improved systems for coupling tubes to ports that eliminate all or some of the above problems. 
     SUMMARY OF THE INVENTION 
     In a first independent aspect of the present invention, a method for coupling a tube to a tube fitting includes:
         radially outwardly expanding a tubular compression collar from a constricted state to an expanded state, the compression collar having a throughway extending there through and being comprised of a resiliently flexible material;   inserting an end of a tube within the throughway of the expanded compression collar, the tube bounding a passage;   inserting a tube fitting within the passage of the tube either before or after inserting the end of the tube within the throughway of the expanded compression collar; and   allowing the tubular compression collar to resiliently rebound back towards the constricted state so that the compression collar pushes the tube against the tube fitting.       

     In one example, the step of radially outwardly expanding the tubular compression collar includes:
         inserting the prongs of an expander into the throughway of the tubular compression collar while in the constricted state; and   radially outwardly moving the prongs so as to expand the compression collar to the expanded state.       

     In another example, the step of radially outwardly expanding the tubular compression collar includes:
         inserting a bladder within the throughway of the tubular compression collar while in the constricted state;   expanding the bladder so as to expand the compression collar to the expanded state.       

     In another example, the step of radially outwardly expanding the tubular compression collar comprises advancing a rotating mandrel within the throughway of the tubular compression collar so that the mandrel expands the compression collar to the expanded state. 
     In another example, the mandrel comprises a tapered body and a plurality of rollers rotatably disposed thereon. 
     In another example, the step of radially outwardly expanding the tubular compression collar comprises rotating the tubular compression collar at a sufficiently high speed to cause the compression collar to expand from the constricted state to the expanded state. 
     In another example, the tubular compression collar comprises a tubular body having the throughway extending therethrough and a first stop lip radially inwardly projecting from the tubular body, the step of inserting the end of the tube within the throughway of the expanded compression collar comprising inserting the end of the tube into the throughway until the tube abuts the first stop lip. 
     In another example, the tubular compression collar comprises a tubular body having an interior surface and an opposing exterior surface that extend between a first end and an opposing second end, the interior surface bounding the throughway extending through the tubular body, a first window extends laterally through the tubular body between the interior surface and the exterior surface, the tube being visible through the window when the end of the tube is within the throughway of the expanded compression collar. 
     In another example, the step of inserting the tube fitting within the passage of the tube comprises inserting a tubular port of the tube fitting into the passage of the tube. 
     In another example, the step of inserting the tube fitting within the passage of the tube comprises inserting an annular barb of the tube fitting within the passage of the tube. 
     In another example, the compression collar is radially outwardly expanded without concurrently radially outwardly expanding the tube. 
     In another example, it takes at least 30 minutes for the compression collar to rebound so as to lose 90% of its expansion from the constricted state to the expanded state. 
     In another example, the throughway has a diameter, the diameter being expanded by at least 150% relative to the original constricted state as the compression collar is moved from the constricted state to the expanded state. 
     In another example, the tube fitting is inserted within the passage of the tube while at least a portion of the tube is disposed within the throughway of the compression collar. 
     In another example, the tube fitting is inserted within the passage of a portion of the tube while the portion of the tube is disposed outside of the throughway of the expanded compression collar. 
     In another example, gamma radiation is applied to the tubular compression collar while or after the tubular compression collar resiliently rebounds back towards the constricted state. 
     In another example, the tubular compression collar is comprised of high-density polyethylene (HDPE) and the step of applying the gamma radiation increases the stiffness of the compression collar. 
     In another example, the compression collar comprises a tubular body having the throughway extending between a first end and an opposing second end, a spacer tab outwardly projects from the first end of the tubular body, the method further comprising positioning the tube fitting so that a flange of the tube fitting butts against a terminal end of the spacer tab. 
     In another example, the compression collar comprises a tubular body having an interior surface that at least partially bounds the throughway, one or more compression ribs radially inwardly project from the interior surface of the body, the one or more compression ribs press against the tube when the compression collar rebounds back towards the constricted state. 
     In a further independent aspect of the present invention, a method for coupling a tube includes:
         radially outwardly expanding a tubular compression collar from a constricted state to an expanded state, the compression collar having a throughway extending there through and being comprised of a resiliently flexible material;   allowing the tubular compression collar to resiliently rebound so that the tubular compression collar constricts to compress a tube against a tube fitting that are at least partially disposed within the throughway of the tubular compression collar; and   applying radiation to the compression collar while or after the compression collar resiliently rebounds.       

     In one example, the tubular compression collar is comprised of a cross-linked polyethylene. 
     In another example, the radiation comprises gamma radiation. 
     In another example, the gamma radiation increasing the stiffness of the compression collar. 
     In a further independent aspect of the present invention, a tubular compression collar used for coupling a tube to a tube fitting includes:
         a tubular body comprised of a resiliently flexible material and having an interior surface and an opposing exterior surface that extend between a first end and an opposing second end, the interior surface bounding a throughway extending through the tubular body; and   a first window extending laterally through the tubular body between the interior surface and the exterior surface.       

     In one example, the tubular body is comprised of a cross-linked polyethylene. 
     In another example, the first end of the tubular body terminates at a terminal end face, the first window extending through a portion of the terminal end face. 
     In another example, wherein the first window has an arched shaped configuration. 
     In another example, the first window is completely encircled by the tubular body. 
     In another example, a second window extends laterally through the tubular body between the interior surface and the exterior surface, the second window being spaced apart from the first window. 
     In another example, the second window is disposed on a side of the tubular body that is opposite the first window. 
     In another example, the second window is spaced apart from the first window along a length of the tubular body. 
     In another example, one or more spacer tabs outwardly projecting from the first end of the tubular body. 
     In another example, the first end of the tubular body terminates at a terminal end face, the one or more spacer tabs outwardly project from the terminal end face so as to extend parallel to a longitudinal axis of the tubular body. 
     In another example, a first stop lip radially inwardly projecting from the tubular body at the first end. 
     In another example, the first end of the tubular body terminates at a terminal end face, the first stop lip radially inwardly projecting from the terminal end face. 
     In another example, the first stop lip radially inwardly projects from the interior surface of the compression collar. 
     In another example, a second stop lip radially inwardly projecting from the tubular body at the first end, the second stop lip being radially spaced apart from the first stop lip. 
     In another example, the throughway of the tubular body has a length extending between the first end and the opposing second end, at least a majority of the length of the throughway having a constant diameter. 
     In another example, one or more compression ribs radially inwardly project from the interior surface of the tubular body. 
     In another example, one or more annular retention ribs radially outwardly project from the exterior surface of the tubular body. 
     In another example, a hump is formed on and radially outwardly projects from the exterior surface of the tubular body. 
     In a further independent aspect of the present invention, a coupling assembly includes:
         the tubular compression collar,   an end of a tube disposed within the throughway of the compression collar, the tube bounding a passage; and   a tube fitting disposed within the passage of the tube, the compression collar radially inwardly compressing the tube against the tube fitting so that a liquid tight seal is formed between the tube and the tube fitting.       

     In one example, the tube is visible through the first window. 
     In another example, the tube fitting comprises a tubular stem having an annular barb formed thereon. 
     In another example, a first stop lip radially inwardly projecting from the tubular body at the first end thereof, a terminal end of the tube being disposed against the first stop lip. 
     In another example, a first spacer tab outwardly projecting from the first end of the tubular body, an end of the first spacer tab, such as a terminal end, butts against a flange of the tube fitting. 
     In another example, the spacer tab projects so as to extend parallel to a longitudinal axis of the tubular body. 
     In a further independent aspect of the present invention, a tubular compression collar used for coupling a tube to a tube fitting includes:
         a tubular body comprised of a resiliently flexible material and having an interior surface and an opposing exterior surface that extend between a first end and an opposing second end, the interior surface bounding a throughway extending through the tubular body; and   a first compression rib radially inwardly projecting from the interior surface of the tubular body.       

     In one example, the first compression rib is annular and encircles the throughway. 
     In another example, the first compression rib does not encircle the throughway. 
     In another example, a second compression rib radially inwardly projects from the interior surface of the tubular body, the second compression rib being spaced apart from the first compression rib. 
     In another example, the second compression rib is disposed at the same location along the length of the tubular body but is radially spaced apart from the first compression rib. 
     In another example, the second compression rib is spaced apart from the first compression rib along the length of the tubular body. 
     In another example, a first stop lip radially inwardly projects from the tubular body at the first end. 
     In another example, one or more spacer tabs outwardly projecting from the first end of the tubular body. 
     In another example, the first end of the tubular body terminates at a terminal end face, the one or more spacer tabs outwardly projecting from the terminal end face so as to extend parallel to a longitudinal axis of the tubular body. 
     In another example, the tubular body is comprised of a cross-linked polyethylene. 
     In another example, one or more annular retention ribs radially outwardly project from the exterior surface of the tubular body. 
     In a further independent aspect of the present invention, a coupling assembly includes:
         the tubular compression collar;   an end of a tube disposed within the throughway of the compression collar, the tube bounding a passage;   a tube fitting disposed within the passage of the tube, the compression collar radially inwardly compressing the tube against the tube fitting so that a liquid tight seal is formed between the tube and the tube fitting, the first compression rib pressing against the tube.       

     In one example, the tube fitting comprises a tubular stem having an annular barb outwardly projecting therefrom. 
     In a further independent aspect of the present invention, a tubular compression collar used for coupling a tube to a tube fitting includes:
         a tubular body comprised of a resiliently flexible material and having an interior surface and an opposing exterior surface that extend between a first end and an opposing second end, the interior surface bounding a throughway extending through the tubular body; and   a first spacer tab outwardly projecting from the first end of the tubular body.       

     In one example, the first spacer tab projects longitudinally away from the tubular body. 
     In another example, the first spacer tab projects parallel to longitudinal axis of the tubular body. 
     In another example, a second spacer tab outwardly projects from the first end of the tubular body and is spaced apart from the first spacer tab. 
     In another example, the first end of the tubular body terminates at a terminal end face, the first spacer tab outwardly projects from the terminal end face so as to extend parallel to a longitudinal axis of the tubular body. 
     In another example, the compression collar includes at least one of:
         a hump disposed on and outwardly projecting from the exterior surface of the tubular body;   a window extending through the tubular body; and   an annular retention rib radially outwardly projecting from the exterior surface of the tubular body.       

     In a further independent aspect of the present invention, a coupling assembly includes:
         the tubular compression collar;   an end of a tube disposed within the throughway of the compression collar, the tube bounding a passage;   a tube fitting having an outwardly projecting flange and an end disposed within the passage of the tube, the compression collar radially inwardly compressing the tube against the tube fitting so that a liquid tight seal is formed between the tube and the tube fitting.       

     In one example, a terminal end of the first spacer tab is butted against the flange of the tube fitting. 
     Each of the above independent aspects of the invention may further include any of the features, options and possibilities set out elsewhere in this document, including those associated with each of the other aspects. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
         FIG. 1  is a front perspective view of a compression collar; 
         FIG. 2  is a rear perspective view of the compression collar shown in  FIG. 1 ; 
         FIG. 3  is an elevated side view of the compression collar shown in  FIG. 1 ; 
         FIG. 4  is a cross sectional side view of the compression collar shown in  FIG. 1 ; 
         FIG. 5  is an exploded view showing the compression collar of  FIG. 1 , a tube, and a tube fitting; 
         FIG. 6  is a perspective view of an alternative embodiment of a tube fitting coupled to a container; 
         FIG. 7  is a perspective view of an expander; 
         FIG. 8A  is an enlarged perspective view of the expansion mechanism of the expander shown in  FIG. 7  with the expansion mechanism in collapsed position; 
         FIG. 8B  is a perspective view of the expansion mechanism shown in  FIG. 8A  in an expanded position; 
         FIG. 9  is a perspective view of the expansion mechanism of  FIG. 8A  with the compression collar of  FIG. 1  disposed thereon; 
         FIG. 10A  is a rear perspective view of the tube of  FIG. 5  received within the expanded compression collar; 
         FIG. 10B  is a front perspective view of the assembly shown in  FIG. 10A ; 
         FIG. 11  is elevated side view of the assembled tube fitting, tube, and compression collar shown in  FIG. 5 ; 
         FIG. 12  is a cross sectional side view of the assembly shown in  FIG. 11 ; 
         FIG. 13  is a front perspective view of an alternative embodiment of a compression collar; 
         FIG. 14  is a rear perspective view of the alternative compression collar shown in  FIG. 13 ; 
         FIG. 15  is a cross sectional side view of the alternative compression collar shown in  FIG. 13  coupled with the tube and the tube fitting; 
         FIG. 16  is a perspective view of an alternative embodiment of a compression collar having a tubular body with a single spacer tab outwardly projecting therefrom; 
         FIG. 17A  is a perspective view of the compression collar shown in  FIG. 16  in an expanded state and being coupled with a tube and tube fitting; 
         FIG. 17B  is an elevated side view of the compression collar of  FIG. 17A  in a constricted state coupling the tube with the tube fitting; 
         FIG. 18  is an alternative embodiment of the compression collar shown in  FIG. 16  have two spacer tabs projecting from the tubular body; 
         FIG. 19  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 18  having three spacer tabs projecting from the tubular body; 
         FIG. 20  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 16  where the compression collar further includes a single annular compression rib radially inwardly projecting from the tubular body; 
         FIG. 21  is a bottom perspective view of the compression collar shown in  FIG. 20 ; 
         FIG. 22  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 20  having a second annular compression rib radially inwardly projecting from the tubular body; 
         FIG. 23  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 22  having six annular compression ribs radially inwardly projecting from the interior surface of the tubular body; 
         FIG. 24  is a perspective view of another alternative embodiment of the compression collar shown in  FIG. 16  where the compression collar further includes a plurality of radially spaced apart compression ribs radially inwardly projecting from the interior surface of the body; 
         FIG. 25  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 24  including a second set of radially spaced apart compression ribs that are disposed at a second distance along the length of the tubular body; 
         FIG. 26  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 16  comprising a plurality of spaced apart compression ribs disposed over the entire interior surface of the tubular body; 
         FIG. 27  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 16  where the compression collar further includes a retention rib radially outwardly projecting from the exterior surface of the tubular body; 
         FIG. 28  is a bottom perspective view of the compression collar shown in  FIG. 27 ; 
         FIG. 29  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 27  that further includes a second retention rib outwardly projecting from the first end of the tubular body; 
         FIG. 30  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 29  wherein the second retention rib is disposed at a second end of the tubular body; 
         FIG. 31  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 16  which includes gripping formed on the exterior surface of the tubular body; 
         FIG. 32  is a perspective view of an alternative embodiment of a compression collar having a single window extending through the tubular body; 
         FIG. 33  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 32  where the compression collar has three radially spaced apart windows extending through the tubular body; 
         FIG. 34  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 32  where the compression collar a second window extending through the tubular body that is longitudinally spaced apart from the first window; 
         FIG. 35  is a perspective view of an alternative embodiment of the compression collar shown in  FIG. 34  where the compression collar has two pairs of windows that are spaced apart along the longitudinally length of the tubular body; 
         FIG. 36  is a perspective view of the compression collar shown in  FIG. 35  where the compression collar has three sets of windows that are spaced apart radially and along the length of the tubular body; 
         FIG. 37  is a perspective view of an alternative embodiment of a compression collar having a hump formed on the exterior surface of the tubular body; 
         FIG. 38  is a perspective view of an alternative embodiment of a compression collar that includes a spacer tab, radially spaced apart compression ribs, and a annular retention rib; 
         FIG. 39  is a perspective view of an alternative embodiment of an expander in the form of a mandrel; 
         FIG. 40  is an elevated front view of the expander shown in  FIG. 39 ; 
         FIG. 41  is a perspective view of an alternative embodiment of the expander shown in  FIG. 39  wherein the rollers are aligned with the longitudinal axis of the expander; 
         FIG. 42  is an elevated side view of an alternative expander having a bladder in an unexpanded state; 
         FIG. 43  is a cross sectional side view of the expander shown in  FIG. 42  taken along lines  43 - 43 ; and 
         FIG. 44  is an elevated side view of the expander shown in  FIG. 42  with the bladder in an expanded state. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before describing various embodiments of the present disclosure in detail, it is to be understood that this disclosure is not limited to the parameters of the particularly exemplified systems, methods, and/or products, which may, of course, vary. Thus, while certain embodiments of the present disclosure will be described in detail, with reference to specific configurations, parameters, features (e.g., components, members, elements, parts, and/or portions), etc., the descriptions are illustrative and are not to be construed as limiting the scope of the claimed invention. In addition, the terminology used herein is for describing the embodiments, and is not necessarily intended to limit the scope of the claimed invention. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure pertains. 
     Various aspects of the present disclosure, including systems, processes, and/or products may be illustrated with reference to one or more embodiments or implementations, which are exemplary in nature. As used herein, the terms “embodiment” and “implementation” mean “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other aspects disclosed herein. 
     As used throughout this application the words “can” and “may” are used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Additionally, the terms “including,” “having,” “involving,” “containing,” “characterized by,” as well as variants thereof (e.g., “includes,” “has,” and “involves,” “contains,” etc.), and similar terms as used herein, including the claims, shall be inclusive and/or open-ended, shall have the same meaning as the word “comprising” and variants thereof (e.g., “comprise” and “comprises”), and do not exclude additional, un-recited elements or method steps, illustratively. 
     It will be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a “stop lip” includes one, two, or more stop lips. 
     As used herein, directional terms, such as “top,” “bottom,” “left,” “right,” “up,” “down,” “upper,” “lower,” “proximal,” “distal” and the like are used herein solely to indicate relative directions and are not otherwise intended to limit the scope of the disclosure and/or claimed invention. 
     Various aspects of the present disclosure can be illustrated by describing components that are bound, coupled, attached, connected, and/or joined together. As used herein, the terms “bound,” “coupled”, “attached”, “connected,” and/or “joined” are used to indicate either a direct association between two components or, where appropriate, an indirect association with one another through intervening or intermediate components. In contrast, when a component is referred to as being “directly bound,” “directly coupled”, “directly attached”, “directly connected,” and/or “directly joined” to another component, no intervening elements are present or contemplated. Furthermore, binding, coupling, attaching, connecting, and/or joining can comprise mechanical and/or chemical association. 
     To facilitate understanding, like reference numerals (i.e., like numbering of components and/or elements) have been used, where possible, to designate like elements common to the figures. Specifically, in the exemplary embodiments illustrated in the figures, like structures, or structures with like functions, will be provided with similar reference designations, where possible. Specific language will be used herein to describe the exemplary embodiments. Nevertheless, it will be understood that no limitation of the scope of the disclosure is thereby intended. Rather, it is to be understood that the language used to describe the exemplary embodiments is illustrative only and is not to be construed as limiting the scope of the disclosure (unless such language is expressly described herein as essential). Furthermore, multiple instances of an element and or sub-elements of a parent element may each include separate letters appended to the element number. Furthermore, an element label with an appended letter can be used to designate an alternative design, structure, function, implementation, and/or embodiment of an element or feature without an appended letter. Likewise, an element label with an appended letter can be used to indicate a sub-element of a parent element. However, element labels including an appended letter are not meant to be limited to the specific and/or particular embodiment(s) in which they are illustrated. In other words, reference to a specific feature in relation to one embodiment should not be construed as being limited to applications only within said embodiment. 
     It will also be appreciated that where multiple possibilities of values or a range a values (e.g., less than, greater than, at least, or up to a certain value, or between two recited values) is disclosed or recited, any specific value or range of values falling within the disclosed range of values is likewise disclosed and contemplated herein. Thus, disclosure of an illustrative measurement or distance less than or equal to about 10 units or between 0 and 10 units includes, illustratively, a specific disclosure of: (i) a measurement of 9 units, 5 units, 1 units, or any other value between 0 and 10 units, including 0 units and/or 10 units; and/or (ii) a measurement between 9 units and 1 unit, between 8 units and 2 units, between 6 units and 4 units, and/or any other range of values between 0 and 10 units. 
     The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. 
     Reference will now be made to the figures of the present disclosure. It is noted that the figures are not necessarily drawn to scale and that the size, orientation, position, and/or relationship of or between various components can be altered in some embodiments without departing from the scope of this disclosure. 
     Depicted in  FIGS. 1-4  is one embodiment of a compression collar  10  incorporating features of the present invention. Compression collar  10  comprises a tubular body  12  having an interior surface  14  and an opposing exterior surface  16  that extend between a first end  18  and an opposing second end  20 . First end  18  terminates at a terminal end face  19  while second end  20  terminates at a terminal end face  21 . 
     Interior surface  14  bounds a throughway  22  that extends through body  12  between first end  18  and second end  20 . Throughway  22  typically has a circular transverse cross section. With the exception of the location of stop lips, as discussed below, throughway  22  can have a constant diameter D extending along the length of body  12 . In other embodiments, interior surface  14  can outwardly flare at second end  20  to assist in easy and guided insertion of a tube within throughway  22  from second end  20 . As such, diameter D of throughway  22  will typically have a constant diameter over at least or less than 40%, 60%, 80%, 90%, 95%, or 98% of the length of throughway  22  or in a range between any two of the foregoing. 
     Compression collar  10  can be formed having a variety of different sizes depending on intended use and depending on the size of the tube to be used with compression collar  10 . In some embodiments, the maximum diameter D can be at least or less than 4 mm, 6 mm, 8 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 40 mm or in a range between any two of the foregoing. Other dimensions can also be used. Compression collar  10  can also have a length L 1  extending between end faces  19  and  21  that can be at least or less than 4 mm, 6 mm, 8 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 40 mm or in a range between any two of the foregoing. Other dimensions can also be used. 
     In the depicted embodiment, body  12  is formed having a pair of windows  26 A and  26 B. More specifically, window  26 A extends laterally through body  12  from exterior surface  16  to interior surface  14  at first end  18  so as to communicate with throughway  22 . In the depicted embodiment, window  26 A also extends through or is recessed into terminal end face  19 . Window  26 A is partially bounded by a recessed surface  28  having an arched configuration. The arched configuration can be elongated, as depicted, or can be semi-circular, U-shaped, C-shaped or have other arched shaped configurations. Window  26 B has the same design and configuration of window  26 A except that it is formed on the opposing side of body  12  at first end  18 . All elements and alternatives discussed with window  26 A are also applicable to window  26 B. As discussed below in greater detail, windows  26  enable visual inspection to tubes or other structures that may be received within throughway  22 . 
     Although body  12  is shown as having two opposing windows  26 , in alternative embodiments, body  12  can be formed with at least or less than one window, two windows, three windows, four windows and any other desired number of windows. In addition, windows need not be arched but could have other configuration that recess into terminal end face  19  and pass through body  12 . For example, windows  26  could comprise a notch having the shape of a V, square, rectangle, polygon, square, linear slot, or other configurations. In addition, windows  26  need not be positioned on opposing sides of body  12  but can be merely spaced apart. In still other embodiments, windows  26  need not be recessed into end face  19  but could be spaced back from end face  19  so that the one or more windows  26  form an aperture extending through body  12  that is completely encircled by body  12 . Again, any desired shape could be used for such windows and any of the above desired numbers of windows can be formed. 
     As also depicted in  FIGS. 1, 3, and 4 , compression collar  10  can comprise a pair of stop lips  32 A and  32 B. Specifically, stop lip  32 A radially inwardly projects at first end  18  of body  12  so as to be aligned with and/or disposed within throughway  22 . That is, stop lip  32 A can radially inwardly project from interior surface  14  at first end  18  into throughway  22  or can be mounted on terminal end face  19  and inwardly project so as to be aligned with throughway  22 . Stop lip  32 A typically has a length L 2  projecting into throughway  22 , i.e., the length extending between body  12  and a terminal tip  34 , that is at least or less than 2%, 5%, 10%, 15%, 20% or 25% of the diameter D of throughway  22  adjacent to stop lip  32 A or is in a range between any two of the foregoing. As discussed below in more detail, stop lip  32 A functions as a stop for a tube or other structure being inserted into throughway  22  from second end  20  so that the tube or other structure is properly positioned within compression collar  10 . 
     Stop lip  32 B can have the same configuration, dimensions and relative positioning as stop lip  32 A except that stop lip  32 B is spaced apart from stop lip  32 B. More commonly, stop lip  32 B is typically disposed on the opposing side of body  12  so that stop lips  32 A and  32 B project inwardly towards each other. Stop lips  32 A and  32 B can also be disposed in a common plane. In the depicted embodiment, two stop lips  32 A and  32 B are shown. In an alternative embodiment, at least or less than one, two, three, four or more stop lips  32  can be disposed on body  12 . Furthermore, in the depicted embodiment stop lips  32 A and  32 B are shown at or directly adjacent to terminal end face  19 . In other embodiments, the one or more stop lips can be formed on interior surface  14  at a location spaced away from terminal end face  19  and toward second end  20 . In other embodiments, stop lips  32  can be eliminated. As such, first end  18  could be formed only having the one or more windows  26  formed thereon and no stop lips  32  or could be formed only having the one or more stop lips  32  formed thereon and no windows  26 . In yet other embodiments, both stop lips  32  and windows  26  can be eliminated so that first end  18  can have the same configuration as second end  20 . 
     It is appreciated that compression collar  10  can also be described in a slightly alternative way. For example, in the above discussion compression collar  10  comprises tubular body  12  that extends between end faces  19  and  21  while windows  26 A and  26 B extend laterally through body  12  at first end  18 . In contrast, however, with continued reference to  FIGS. 1-4 , compression collar  10  can also be described as comprising tubular body  12  that extends between an annular terminal end face  23  at first end  18  and annular terminal end face  21  at second end  20 . A pair of spacer tabs  24 A and  24 B outwardly project from terminal end face  23 . In the depicted embodiment, spacer tabs  24  project so as to extend parallel to a longitudinal axis  25  of tubular body  12  and more specifically to a central longitudinal axis  25  of throughway  22 . Spacer tabs  24 A and  24 B are spaced apart and project from opposing sides of terminal end face  23  so that throughway  22  is disposed therebetween. Each spacer tab  24  has an interior surface  29  and an opposing exterior surface  30  that extend to terminal end face  19 , that was previously referenced. 
     Although not required, in one embodiment interior surface  29  can extend flush with and continuously with interior surface  14  of tubular body  12 . Stop lips  32 A and  32 B radially inwardly project from spacer tabs  24 A and  24 B, respectively. Stop lips  32  can project from interior surface  29  or terminal end face  19  of spacer tabs  24 A and  24 B. In contrast to describing windows  26 A and  26 B as passing through tubular body  12 , windows  26 A and  26 B are now described as begin bounded by the opposing ends of spacer tabs  24 A and  24 B and being bounded on one side by terminal end face  23  of tubular body  12 . 
     Compression collar  10  is typically comprised of a polymeric material having memory properties, i.e., the material will resiliently rebound towards its original shape when stretched. One common example of a polymeric material having memory properties that can be used to form compression collar  10  is cross-linked polyethylene that is commonly abbreviated as PEX. PEX is commonly formed from high-density polyethylene (HDPE). PEX contains cross-linked bonds in the polymer structure that change the thermoplastic to a thermoset. Depending on the manufacturing process and the specific type of material used to form compression collar  10 , the cross-linking can be accomplished prior to, during or after the forming of compression collar  10 . The required degree of cross-linking is typically between 65% and 89%. A higher degree of cross-linking could result in brittleness and stress cracking of the material, while a lower degree of cross-linking could result in product with poor physical properties. 
     For some cross-linking materials, e.g. some HDPE materials, the cross-linking or at least a majority of the cross-linking can automatically be achieved during the manufacture process, especially where the material forming the compression collar is heated during the forming process. A Silane or “moisture cure” method can also be used to further facilitate the desire cross-linking. In this method, the formed compression collars are placed in a heated water bath or in a heated environmental chamber having a relative humidity of between 60% and 98% and allowed to cure for a sufficient time to achieve the desired cross-linking. Other applications of heat and moisture can also facilitate the needed cross-linking. 
     For some alternative cross-linking materials, the cross-linking can be accomplished by applying radiation, such as electron beam radiation (ebeam), to the polymer, as is commonly known in the art. For example, in one method of cross-linking the polymer, compression collar  10  is subject to at least or less than 50 kGy, 60 kGy, 70 kGy or 80 kGy of ebeam or in a range between any two of the foregoing, after being molded. Other amounts can also be used. 
     In one method of manufacture, compression collar  10  can be formed by a molding process such as injection molding. The injection molding process heats the material which can facilitate at least a majority of the needed cross-linking. Using an injection molding process enables the compression collar  10  to be easily formed with rounded corners so as to avoid or limit sharps. Typically, compression collar  10  will be molded and then subjected to post cross-linking process, such as discussed above. However, the desired cross-linking can be achieved during the initial manufacturing process either as a result of the manufacture process and/or by applying heat and/or humidity during manufacture and/or applying radiation during manufacture. It is appreciated that other molding processes such as blow molding, rotational molding, and the like can also be used to form compression collar  10 . Other manufacturing processes can also be used to form compression collar  10 . For example, compression collar  10  could be machined or cut from an extruded tube of material. Other methods can also be used. 
     As depicted in  FIG. 5 , compression collar  10  can be used to secure a tube  40  to a tube fitting  42  so that a liquid tight seal is formed between tube  40  and tube fitting  42 . More specifically, tube  40  comprises an encircling side wall  44  having an interior surface  46  and an opposing exterior surface  48 . Interior surface  46  bounds a passage  50  extending along the length of tube  40 . Tube  40  has a first end  52  that terminates at a terminal end face  54 . Tube  40  is also typically made of a polymeric material having memory properties. Although in some embodiments tube  40  can be made of the same material as compression collar  10 , as discussed above, tube  40  is commonly made from a material that is different from the material for compression collar  10 . Typically, the material for tube  40  has a modulus of elasticity that is lower than the modulus of elasticity for the material of compression collar  10 . That is, the material for tube  40  is typically more flexible than the material used to form compression collar  10 . Examples of materials that can be used for tube  40  that have a lower modulus of elasticity include silicone, polyvinyl chloride (PVC), and thermoplastic elastomers (TPE). Other materials can also be used. It is appreciated that tube  40  can have any desired diameter and any desired length. 
     The term “tube fitting” as used in the specification and appended claims is broadly intended to include any type of fitting or other structure designed for coupling with tube  40 . For example, tube fitting  42  could comprise a coupling fitting, union fitting, port fitting, plug fitting, T-fitting, Y-fitting, elbow fitting, reducer fitting, adapter fitting or the like. Tube fitting  42  may be a standalone structure or may be attached to or be configured to be attach to another structure such as a bag, container, tube, or other fitting. Commonly, at least a portion of tube fitting  42  is designed to be received within passage  50  of tube  40  for making a connection therewith. It is also common that tube fitting  42  is tubular so that a sealed fluid connection can be formed between tube fitting  42  and tube  40 . In other embodiments, however, such as where tube fitting  42  is a plug, tube fitting  42  need not be tubular. 
     In the depicted embodiment, tube fitting  42  comprises a coupling fitting used to fluid couple two separate tubes together. Tube fitting  42  comprises a stem  64  having a first end  60  and an opposing second end  62 . Formed on and radially encircling exterior surface  66  of stem  64  at first end  60  is an annular barb  68 A having a frustoconical configuration. Barb  68 A includes an annular outside shoulder  69 . Although stem  64  is shown having a single barb  68 A formed thereon, in other embodiment, stem  64  can be formed with at least or less than one, two, three, four or more consecutive or spaced apart barbs  68 A formed thereon. Formed on and radially encircling exterior surface  66  of stem  64  at second end  62  is an annular barb  68 B having the same configuration and elements as barb  68 A. Again, stem  64  can be formed with at least or less than one, two, three, four or more barbs  68 B formed thereon. Although not required, a flange  70  encircles and radially outwardly extends from stem  64  at a location between barbs  68 A and  68 B. As also shown in  FIG. 5 , stem  64  can be tubular having an interior surface  72  that bounds a passage  74  that extends through stem  64  between opposing ends  60  and  62 . 
     Tube fitting  42  is typically molded from a polymeric material. However, other materials and molding processes can also be used. Tube fitting  42  is also typically made from a material that is different from the material used to form tube  40  and compression collar  10 . In addition, the material used to form tube fitting  42  typically has a modulus of elasticity that is greater than the modulus of elasticity of the materials used to form tube  40  and compression collar  10 . That is, tube fitting  42  is typically less flexible than tube  40  and compression collar  10 . 
     As previously discussed, tube fitting  42  can have a variety of different configurations. For example, depicted in  FIG. 6  is one example of tube fitting  42 A that comprises a port fitting and is coupled to a container  130 . Like elements between tube fittings  42  and  42 A are identified by like reference characters. Tube fitting  42 A includes tubular stem  64  having annular barb  68 A formed on first end  60  thereof. The alternative number of barbs  68 A as discussed above with regard to tube fitting  42  are also applicable to tube fitting  42 A. In contrast to tube fitting  42 , tube fitting  42 A has second end  62  with a flange  133  outwardly projecting therefrom. In this embodiment, flange  133  is secured to an interior surface  132  of container  130  such as by welding or adhesive. Stem  64  extends through an opening in container  130 . 
     Container  130  can comprise a rigid, semi-rigid or flexible container. For example, container  130  can comprise a collapsible, flexible bag made from one or more sheets of polymeric film. The polymeric film can comprise a flexible, water impermeable material, such as a low-density polyethylene, and may have a thickness that is at least or less than 0.02 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm or in a range between any two of the foregoing. The film is may be sufficiently flexible that it can be rolled into a tube without plastic deformation and/or can be folded over an angle of at least 90°, 180°, 270°, or 360° without plastic deformation. Other materials can also be used. 
     When using compression collar  10  to secure tube fitting  42  to tube  40 , compression collar  10  is first expanded from an initial constricted state to an expanded state. As depicted in  FIG. 7 , compression collar  10  can be expanded using an expander  80 . In general, expander  80  comprises a housing  82  having a top surface  84  with an annular stop ring  86  disposed thereon. Stop ring  86  encircles and opening  88  extending therethrough. Disposed within opening  88  is an expansion mechanism  90 . As depicted in  FIGS. 8A and 8B , expansion mechanism  90  comprises a plurality of elongated fingers  92  that are radially spaced about a common central axis  94 . In general, each finger  92  comprises an elongated base  96  and an elongated prong  98  outwardly projecting from each base  96 . More specifically, each base  96  has a wedge or pie shaped cross sectional configuration with a top face  100  that extends between a constricted inside end  101  and an opposing widened outside face  102 . Top face  100  is shown as being flat while widened outside face  102  is rounded or arced. Each prong  98  upwardly projects from top face  100  of each base  96  at constricted inside end  101 . Each prong  98  also has a wedge or pie shaped cross sectional configuration that extends between a constricted inside end  104  and a widened outside face  106 . Outside face  106  is rounded or arced. 
     Fingers  92  can move between a collapsed position, as shown in  FIG. 8A , and an expanded position, as shown in  FIG. 8B . In the collapsed position fingers  92  move together so as to encircle a common central axis  94 . More specifically, bases  96  combine to form a cylinder having a central axis  94  that includes a flat, circular, top surface  108  and a cylindrical side wall  110 . Prongs  98  also concurrently move together to form a cylinder having the same central axis  94  that includes a flat, circular, top surface  112  and a cylindrical side wall  114 . 
     As fingers  92  move from the collapsed position of  FIG. 8A  to the expanded position of  FIG. 8B , each base  96  and prong  98  moves radially outward away from central axis  94 . Fingers  92  move outwardly until they hit against stop ring  86 . Stop ring  86  thus prevents fingers  92  from expanding farther than desired. 
     In the depicted embodiment, expansion mechanism  90  includes six fingers  92  and thus six bases  96  and six prongs  98 . In alternative embodiments, it is appreciated that expansion mechanism  90  can be formed with at least or less than 2, 3, 4, 5, 6, 7, 8, 9, or 10 fingers  92  and a corresponding number of bases  96  and prongs  98 . The number of fingers  92  can also be in the range between any two of the foregoing numbers. Other numbers of fingers  92  could also be used. It is appreciated that any form of drive mechanism, such as a gear drive, pneumatic drive, hydraulic drive, belt drive and the like, can be used to move fingers  92  between the collapsed and expanded positions. It is also appreciated that expander  80  is only one example of an expander that can be used to expand compression collar  10 . It is appreciated that any form of expander that will function of expand compression collar  10 , as discussed below, can be used in the methods of the present invention. 
     During use, expansion mechanism  90  is initially moved to the collapsed position. As depicted in  FIG. 9 , second end  20  of compression collar  10  is then advanced over prongs  98  so that prongs  98  are received within throughway  22  ( FIG. 4 ). Compression collar  10  can be advanced until stopped by the free end of prongs  98  hitting against stop lips  32  and/or second end  20  of compression collar  10  hitting against top surface  108  of bases  96 . In either event, prongs  98  extend the full length or substantially the full length of throughway  22 . For example, prongs  98  can extend at least 80%, 90%, 95% or 98% of the full length of throughway  22 . Once compression collar  10  is properly positioned on prongs  98 , fingers  92  are moved radially outward to the expanded position, as shown in  FIG. 8B , thereby radially stretching compression collar  10  from its constricted state to its expanded state. 
     Once compression collar  10  is stretched to the expanded state, fingers  92  are again moved back toward the retracted position so that compression collar  10  can be freely removed from fingers  92 . Compression collar  10  begins to automatically, resiliently rebound back toward its constricted state as soon as it is released from prongs  98 . Compression collar  10  will typically rebound to lose 50% of its expansion within 30 second of being released. Because of the mechanical properties of compression collar  10 , however, it will typically take at least 30 minutes and more commonly at least 1 hour or 2 hours for compression collar  10  to rebound so as to lose 90% of its expansion. The time for rebounding is in part dependent upon the extent of the original stretching. In the present invention, a compression collar  10  of a set size may stretched to different ratios depending on its intended use. In some uses, compression collars disclosed herein are typically expanded to at least or less than 115%, 130%, 140%, 150%, 160%, 180%, 200%, 210% of their original constricted diameter or in a range between any two of the forgoing. For example, the diameter D in  FIG. 4  can be expanded to the foregoing percentages. Other values can also be used. Furthermore, there may be some plastic deformation of compression collar  10  in the original stretching. As such, compression collar  10  may not be able to fully return to its original constricted state. 
     It is appreciated that the use of expander  80  is only one of many methods that can used to expand compression collar  10 . By way of example and not by limitation, compression collar  10  could also be expanded by inserting a bladder, either elastomeric or non-elastomeric, within throughway  22  and then expanding the bladder to expand compression collar  10 . In another method, compression collar  10  can be rapidly spun to produce expansion by centrifugal force. In still another method, a tapered punch could be linearly pressed into throughway  22  for expanding compression collar  10 . As discussed below in further detail, in still other methods, a tapered mandrel can be rotated and advanced within throughway  22  to expand compression collar  10 . Rollers or air bearings could be disposed on the mandrel to reduce friction and damage to the compression collar. Other methods can also be used. 
     Turning to  FIGS. 10A and 10B , once compression collar  10  is in the expanded state, first end  52  of tube  40  is advanced into throughway  22  of compression collar  10  until first end  52  butts against one or both of stop lips  32 . Stop lips  32  thus help to properly position tube  40  within compression collar  10 . 
     As depicted in  FIGS. 11 and 12 , once tube  40  is properly positioned within compression collar  10 , first end  60  of tube fitting  42  is advanced into passage  50  of tube  40  at first end  52  while tube  40  is supported within compression collar  10 . Tube fitting  42  is typically advanced into passage  50  prior to significant constricting of compression collar  10  so that compression collar  10  does not interfere with the insertion of tube fitting  42 . Furthermore, tube  40  is typically sufficiently flexible that tube fitting  42  can be manually pressed into passage  50 . In other embodiments, however, a tool or machine can be used to assist in the insertion of tube fitting  42 . 
     In the depicted embodiment, tube fitting  42  is advanced until flange  70  butts against compression collar  10 . Windows  26  enable a visual inspection of first end  52  of tube  40  to ensure that first end  52  remains adjacent to or butted against the interior surface of stop lips  32  while flange  70  is positioned adjacent to or butted against the opposing exterior surface of stop lips  32 , thereby ensuring that both tube  40  and tube fitting  42  are properly positioned within compression collar  10 . 
     Once tube  40  and tube fitting  42  are properly positioned, compression collar  10  is left to automatically, resiliently rebound back toward the constricted state. At a minimum, compression collar  10  resiliently rebounds so as to have an inner diameter that is smaller than the outer diameter of tube  40 , thereby compressing tube  40 . As compression collar  10  resiliently constricts, it radially inwardly pushes and constricts tube  40 , as depicted in  FIG. 12 , so as to form a uniform, annular, liquid tight seal between tube  40  and barb  68 A. Here it is noted that compression collar  10  is sized relative to tube  40 , as depicted in  FIG. 10B , so that when compression collar  10  is in the expanded state, terminal end face  54  of tube  40  necessarily butts against one or both of stop lips  32  when advanced through throughway  22 , as opposed to freely passing between stop lips  32 . However, compression collar  10  is also configured so that tube fitting  42  can be advanced into passage  50  of tube  40  without significant interference by stop lips  32  of compression collar  10 . That is, tube fitting  42  may cause bending or flexing of stop lips  32  as tube fitting  42  is advanced into passage  50  of tube  40  but stop lips  32  will not preclude coupling of tube fitting  42  and tube  40 . Likewise, compression collar  10  is configured so that stop lips  32  do not prematurely hit against tube fitting  42 , thereby preventing compression collar  10  from properly compressing tube  40  about barb  68 . 
     It is appreciated that a single compression collar  10  can be used with a plurality of different tubes  40  having different diameters within a fixed range of diameters. For tubes  40  outside of the range of diameters, a different sized compression collar  10  can be used. As such a plurality of different sized compression collars  10  can be produced where each compression collar  10  is designed to be used with a plurality of different tubes  40  having different diameters within a fixed range of diameters. 
     As also depicted in  FIG. 12 , tube fitting  42  is typically positioned so that shoulder  69  of barb  68 A is centrally positioned along the length of throughway  22  of compression collar  10 . More specifically, shoulder  69  is typically positioned so as to be located at a distance from the center of the length of throughway  22 , i.e., central axis  25 , that is less than or at least 2%, 4%, 6%, 8%, 10%, 12%, 15%, 20%, 30%, or 40% of the length of throughway  22 . Other positioning can also be used. 
     In an alternative embodiment where compression collar  10  does not include stop lips  32 , it is appreciated that tube  40  could first be passed all the way through expanded compression collar  10 . Tube fitting  42  could then be pressed within passage  50  of tube  40  so the tube fitting  42  still remains outside of compression collar  10 . The combined tube  40  and tube fitting  42  could then be received within throughway  22  of compression collar  10  for being radially compress by compression collar  10 . 
     Although not required, in one embodiment of the present invention, after compression collar  10  has rebounded toward the contracted state so as to compress tube  40  and produce the seal between tube  40  and tube fitting  42 , radiation, such as gamma radiation, can be applied to the assembled compression collar  10 , tube fitting  42  and tube  40 . It is theorized that the applied radiation further increases the cross linking of the polyethylene or other material used to form compression collar  10 . By increasing the cross linking, compression collar  10  becomes stiffer, thereby further securing the connection between tube fitting  42  and tube  40 . This increased connection helps to prevent any unintentional separation or leaking between tube fitting  42  and tube  40  as tube fitting  42  and/or tube  40  are subsequently moved, such as during shipping or use. The application of such radiation prior to the expansion of compression collar  10  may not be desirable because it could make compression collar  10  too rigid for proper expansion. However, applying the radiation after rebounding of the compression collar  10  helps to solidify the secure the engagement between tube fitting  42  and tube  40 . In some methods, the radiation can be applied while and/or after the compression collar  10  is resiliently rebounding toward the constricted state. 
     It is noted that in the above discussed method of assembly that compression collar  10  is moved from the constricted to expanded state independent of tube  40 . That is, tube  40  is not concurrently expanded with compression collar  10 . Rather, compression collar  10  first expanded and then tube  40  is inserted into the expanded compression collar  10  while tube  40  is in it normal unexpanded state. However, in some embodiments, it may be desirable to first insert tube  40  into compression collar  10  and then currently expand both tube  40  and compression collar  10  using expander  80  or some other expander. Tube fitting  42  can then still be received within tube  40  as discussed above. 
     Depicted in  FIGS. 13 and 14  are perspective views of an alternative embodiment of a compression collar  10 A incorporating features of the present invention. Like elements between compression collars  10  and  10 A are identified by like reference characters. Compression collars  10  and  10 A are identical except that compression collar  10 A includes a pair of spaced apart compression ribs  120 A and  120 B disposed on interior surface  14  of tubular body  12  so as to radially inwardly project into throughway  22  and encircle throughway  22 . Although not required, in the depicted embodiment compression ribs are annular, i.e., in the form of annular rings. Compression ribs  120 A and  120 B are typically disposed at or toward first end  18  of body  12  so that when tube fitting  42  and tube  40  are coupled together and disposed within throughway  22  of compression collar  10 A, as shown in  FIG. 15 , compression ribs  120 A and  120 B are disposed between barb  68 A and terminal end face  23  ( FIG. 13 ) of compression collar  10 A. That is, compression ribs  120 A and  120 B project into and compress tube  40  behind barb  68 A so as to further secure tube  40  to tube fitting  42  and further enhance the liquid tight seal between tube  40  and tube fitting  42 . In alternative embodiments, compression collar  10 A can be formed with at least or less than 1, 2, 3, 4, or 5 spaced apart compression ribs or with a range between any two of the foregoing numbers. 
     Depicted in  FIG. 16  is an alternative embodiment of a compression collar  10 B. Like elements between compression collar  10  and  10 B are identified by like reference characters. For example, compression collar  10 B include tubular body  12  extending between terminal end face  23  at first end  18  and terminal end face  21  and second end  20 . Tubular body  12  has interior surface  14  that bounds throughway  22  extending therethrough. However, in contrast to compression collar  10 , compression collar  10 B includes only a single spacer tab  24 A outwardly projecting from first end  18  of tubular body  12 . Single spacer tab  24 A is shown projecting from terminal end face  23 . In turn, only a single window  26 A is formed. Window  26 A is bounded on its opposing ends by the opposing ends of spacer tab  24 A and is bounded on one side by the exposed area of terminal end face  23 . 
     It is appreciated that spacer tab  24 A can have a variety of different widths, i.e., the distance that spacer tab  24 A extends along terminal end face  23 . For example, with reference to the full annular length of terminal end face  23 , spacer tab  24 A can have a width that is at least or less than 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60% of the full annular length of terminal end face  23  or is in a range between any two of the percent values. Spacer tab  24 A also typically has a height H extending between terminal end face  23  and terminal end face  19  that is at least or less than 0.5 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, 4 mm, 5 mm, 7 mm, 10 mm, 15 mm, 20 mm or is in a range between any of the two foregoing values. Height H can vary based on the diameter of tubular body  12 . For example, in some embodiments the height H can increase as the diameter increases. 
     Although spacer tab  24 A can be located at any location along terminal end face  23 , in one embodiment spacer tab  24 A can be positioned to increase the hoop strength of tubular body  12 . For example, in one method of manufacture, as previously discussed, compression collar  10 B can be produced by injection molding. In this method of manufacture, the production material is injected into a mold cavity having a substantially tubular, cylindrical configuration that corresponds to the desired shape of the compression collar. The material typically enters the cavity and flows in opposite directions around the cavity until the material meets up at an intersection location  116  to form a continuous loop. A weld line  117  can be formed where the material flows together and welds together but does not mix. Intersection location  116  and weld line  117  will typically extend along the length of compression collar  10 B between terminal end faces  21  and  23 . The material will often not fully blend or mix at intersection location  116 /weld line  117 , depending on the properties of the material, and thus will be weaker in lateral tension at intersection location  116 /weld line  117 . To help increase the tensile strength of compression collar  10 B at intersection location  116 /weld line  117  so that compression collar  10 B does not fail as it is being radially expanded for attachment, spacer tab  24 A can be formed at intersection location  116 /weld line  117 . That is, by positioning spacer tab  24 A in alignment with intersection location  116 /weld line  117 , more material is disposed along intersection location  116 /weld line  117 , thereby increasing the tensile strength along intersection location  116 /weld line  117  and increasing the overall hoop strength of compression collar  10 B. 
     As a result of spacer tab  24 A, there is typically less radial expansion of tubular body  12  at intersection location  116  during the expansion process than at the remainder of tubular body  12  where spacer tab  24 A does not exist. Thus, to help ensure a more uniform expansion of tubular body  12 , tubular body  12  will often only be made with one spacer tab  24 A formed therein. However, as discussed below, multiple spacer tabs  24  can also be formed. 
     Compression collar  10 B is used in substantially the same way as previously discussed with regard to compression collar  10 . For example, compression collar  10  is initially expanded in the same way as previously discussed with regard to compression collar  10 . Turning to  FIGS. 17A and 17B , once compression collar  10 B is in the expanded state, first end  52  of tube  40  is advanced into throughway  22  of compression collar  10 B. Because compression collar  10 B does not include stop lips  32 , tube  40  can be freely passed entirely through compression collar  10 B, if desired. 
     Next, first end  60  of tube fitting  42  is advanced into passage  50  of tube  40  at first end  52  while tube  40  is partially disposed within throughway  20  of compression collar  10 B. Tube fitting  42  is typically advanced into passage  50  prior to significant constricting of compression collar  10 B so that compression collar  10 B does not interfere with the insertion of tube fitting  42 . Furthermore, tube  40  is typically sufficiently flexible that tube fitting  42  can be manually pressed into passage  50 . In other embodiments, however, a tool or machine can be used to assist in the insertion of tube fitting  42 . 
     Tube fitting  42  is advanced until flange  70  butts against the terminal end of tube  40 . As needed, the assembled tube fitting  42  and tube  40  are moved so that terminal end  19  of spacer tab  24 A butts against flange  70  of tube fitting  42 . That is, tube fitting  42  and tube  40  can be assembled outside of compression collar  10 B and then moved into place. Alternatively, tube  40  or tube fitting  42  can be held at the desired location relative to compression collar  10 B while the other of tube  40  or tube fitting  42  is coupled thereto. In this method, no movement of tube  40  or tube fitting  42  is required relative to compression collar  10 B once tube  40  and tube fitting  42  are coupled together. After tube fitting  42  and tube  40  are properly positioned, compression collar  10  is left to automatically, resiliently rebound back toward the constricted state. At a minimum, compression collar  10  resiliently rebounds so as to have an inner diameter that is smaller than the outer diameter of tube  40 , thereby compressing tube  40 . As compression collar  10  resiliently constricts, it radially inwardly pushes and constricts tube  40 , so as to form a uniform, annular, liquid tight seal between tube  40  and barb  68 A, in the same way as previously discussed and depicted with regard to  FIG. 12 . 
     Window  26 A enables a visual inspection of first end  52  of tube  40  to ensure that first end  52  of tube  40  remains adjacent to or butted against flange  70  while compression collar  10 B is positioned adjacent to or butted against flange  70 , thereby ensuring that both tube  40  and tube fitting  42  are properly positioned within compression collar  10 B so that compression collar  10 B produces the desired liquid tight seal between tube  40  and tube fitting  42 . 
     Depending on the situation, variations in the assembly process may also be used. For example, if tube  40  has a free second end  53  that is opposite first end  52 , tube  40  and tube fitting  42  could be coupled together outside of compression collar  10 B. Once assembled, second end  53  could be advanced through throughway  22  of compression collar  10 B until spacer tab  24 A butts against flange  70  of tube fitting  42 . In yet another alternative, compression collar  10 B may be configured so that in the expanded state, tube fitting  42  (including flange  70 ) can pass entirely through throughway  22 . In this embodiment, tube  40  and tube fitting  42  could again be coupled together outside of compression collar  10 B. Once assembled, tube fitting  42  having tube  40  therein could be advanced through compression collar  10  until the side face of flange  70  is aligned with terminal end face  19  of spacer tab  24 A. The assembly could then be held in this position until compression collar  10 B sufficiently constricts so that spacer tab  24 A butts against flange  70 . Other methods of assembly can also be used depending on the facts. 
     In an alternative embodiment, it is appreciated that compression collar  10 B can be formed with 2, 3, 4, or more spaced apart spacer tabs  24 . For example, depicted in  FIG. 18  is a compression collar  10 C. Compression collar  10 C has the same structural elements and is used in the same way as compression collar  10 B except that compression collar  10 C includes a second spacer tab  24 B projecting from first end  18  of tubular body  12 . Again, spacer tabs  24 A and  24 B are shown projecting from terminal end face  23  and bound windows  26 A and  26 B therebetween. Spacer tabs  24 A and  24 B are opposingly facing and are disposed on opposing sides of terminal end face  23 . Other spacings of spacer tabs  24 A and  24 B can also be used. 
     In another alternative embodiment depicted in  FIG. 19 , a compression collar  10 D is provided. Compression collar  10 D has the same structural elements and is used in the same way as compression collars  10 B and  10 C except that compression collar  10 D also includes a third spacer tab  24 C longitudinally projecting from first end  18  of tubular body  12 . Again, spacer tabs  24 A,  24 B, and  24 C are shown projecting from terminal end face  23  and bound windows  26 A,  26 B, and  26 C therebetween. 
     Depicted in  FIGS. 20 and 21  is another alternative embodiment of a compression collar  10 E that has the same structural elements and can be used in the same way as compression collars  10 B- 10 D. Compression collar  10 E is distinguished from compression collar  10 B by having annular compression rib  120 A inwardly projecting from interior surface  14  at first end  18 . In the depicted embodiment, compression rib  120 A is shown being flush with terminal end face  23 . In other embodiments, compression rib  120 A can be spaced apart from terminal end face  23  and located more toward second end  20 . 
     Compression rib  120 A is positioned and designed to function in the same way as previously discussed with regard to compression collar  10 A when discussing  FIGS. 13-15 . Specifically, compression rib  120 A is positioned so that when tube fitting  42  and tube  40  are coupled together and disposed within throughway  22  of compression collar  10 E, compression rib  120 A is disposed between barb  68 A ( FIG. 15 ) and terminal end face  23  of compression collar  10 E or at terminal end face  23 . Compression rib  120 A projects into and compresses tube  40  behind barb  68 A so as to further secure tube  40  to tube fitting  42  and further enhance the liquid tight seal between tube  40  and tube fitting  42 . In alternative embodiments, compression collar  10 E can be formed with at least or less than 2, 3, 4, or 5 spaced apart compression ribs or with a range between any two of the foregoing numbers. For example, depicted in  FIG. 22  is another alternative embedment of a compression collar  10 F that has the same structural elements and can be used in the same way as compression collar  10 E except that compression collar  10 F also includes second compression rib  120 B. Second compression rib  120 B also radially inwardly projects from interior surface  14  and is located at first end  18  of tubular body  12  but is spaced apart from first compression rib  120 A. Second compression rib  120 B functions the same way as first compression rib  120 A. 
       FIG. 23  shows an alternative embodiment of a compression collar  10 G that has the same structural elements and can be used in the same way as compression collar  10 E. However, compression collar  10 G has a plurality of compression ribs  120 A- 120 F that radially inwardly project from interior surface  14  of tubular body  12  at first end  18 . Compression ribs  120 A- 120 F can each be directly adjacently disposed or can be spaced apart. Again, compression ribs  120 A- 120 F project into and compress tube  40  behind barb  68 A so as to further secure tube  40  to tube fitting  42  and further enhance the liquid tight seal between tube  40  and tube fitting  42 . 
     Depicted in  FIG. 24  is another alternative embodiment of a compression collar  10 H that has the same structural elements and can be used in the same way as compression collar  10 E. In the embodiments of compression collars  10 E- 10 G, compression ribs  120  are shown as being annular, i.e., annular rings. In contrast, compression collar  10 H includes compression ribs  122 A- 122 C that radially inwardly project from interior surface  14  of body  12  at first end  18  but are not annular. Rather, compression ribs  122 A- 122 C are radially spaced apart and are separated by gaps  124 A- 124 C. In the depicted embodiment, compression ribs  122 A- 122 C are disposed at the same location along the length of tubular body  12 . That is, compression ribs  122 A- 122 C are disposed within a common plane that orthogonally passes through longitudinal axis  25  ( FIG. 4 ) of tubular body  12 . In an alternative embodiment, compression ribs  122 A- 122 C can be staggered along the length of tubular body  12  at first end  18 . 
     In the depicted embodiment, three non-annular compression ribs  122 A- 122 C are shown. In alternative embodiments, 1, 2, 4, or more non-annular compression ribs  122  can be used. As with compression ribs  120 , compression ribs  122  project into and compress tube  40  behind barb  68 A so as to further secure tube  40  to tube fitting  42  and further enhance the liquid tight seal between tube  40  and tube fitting  42 . 
     One potential concern with using annular compression ribs  120  is that during the expansion process, prongs  98  from expansion mechanism  90  ( FIG. 8B ) could press against and potentially deform or damage that annular compression ribs  120  so that they no longer properly function to seal tube  40  to tube fitting  42 . By using non-annular, spaced apart compression ribs  122 , expansion mechanism  90  ( FIG. 8B ) can be designed with prongs  98  that sit only within gaps  124  and do not sit directly against compression ribs  122 . Accordingly, as compression collar  10 H is expanded by prongs  98 , there is no risk of compression ribs  122  being deformed or damaged by prongs  98 . 
     Depicted in  FIG. 25  is a further alternative embodiment of a compression collar  10 I that has the same structural elements and can be used in the same way as compression collar  10 H. Compression collar  10 I is the same as compression collar  10 H except that compression collar  10 I includes a second row of compression ribs  122 D- 122 F. Compression ribs  122 D- 122 F can have the same configuration and function as compression ribs  122 A- 122 C and be spaced apart by gaps  124 A- 124 C. Furthermore, compression ribs  122 D- 122 F can have the same alternatives as compression ribs  122 A- 122 C. However, compression ribs  122 D- 122 F are placed at a different location along the length of tubular body  12 . 
     In the above discussed embodiments, compression ribs  122  are depicted as linear and are located at first end  18 . In alternative embodiment, however, the compression ribs need not be linear and can also be located at second end  20 . For example, depicted in  FIG. 26  is a compression collar  10 J having a plurality of compression ribs  126  radially inwardly projecting from interior surface  14 . However, compression ribs  126  are spaced apart over the entire interior surface  14  between first end  18  and second end  20 . Furthermore, compression ribs  126  are shown as being circular. However, in other embodiments, compression ribs could be oval, elliptical, square, irregular or have other polygonal configurations. Compression ribs  126  still function to project into and compress tube  40  so as to further secure tube  40  to tube fitting  42  and further enhance the liquid tight seal between tube  40  and tube fitting  42 . 
     In another alternative embodiment depicted in  FIGS. 27 and 28 , a compression collar  10 K is provided. Compression collar  10 K has the same structural elements and is used in the same way as compression collar  10 B. The distinction between compression collar  10 K and compression collar  10 B is that compression collar  10 K has a retention rib  140 A that radially outwardly projects from exterior surface  16  of tubular body  12  at first end  18 . Retention rib  140 A is depicted as being annular and flush with terminal end face  23 . However, in alternative embodiments, retention rib  140 A can be located at other locations along the length of tubular body  12 , i.e., spaced apart from terminal end face  23 , and need not be annular. For example, retention rib  140 A could comprise a plurality of spaced apart non-annular retention ribs, i.e., 2, 3, 4, or more retention ribs, such as compression ribs  122 . 
     In contrast to compression ribs  120  and  122  that project into and directly compress tube  40 , retention rib  140 A reinforces first end  18  of tubular body  12 . This reinforcement helps to ensure that first end  18  fully constricts after expansion and thereby helps to ensure that compression collar  10 K compresses tube  40  to secure tube  40  to tube fitting  42  and further ensures the liquid tight seal between tube  40  and tube fitting  42 . If desired, more than one retention rib  140  can be formed on tubular body  12 . For example, in  FIG. 29  compression collar  10 K includes a second retention rib  140 B radially outwardly projecting from exterior surface at first end  18 . Retention rib  140 B can have the same alternatives as retention rib  140 A. As desired, 3, 4 or more retention ribs  140  can be used. Furthermore, as depicted in  FIG. 30 , retention rib  140 B or other retention ribs can also be disposed as second end  20 . Even when located at second end  20 , retention ribs  140  help ensure proper constriction of tubular body  12  for compressing tube  40 . 
     Depicted in  FIG. 31  is compression collar  10 B as previously discussed above with regard to  FIG. 16 . However, compression collar  10 B has now been modified to include gripping  144  formed on exterior surface  16 . Gripping  144  can be in the form of linear ribs or any other shape of projections that will assist a using in gripping and moving compression collar  10 B. For example, gripping can be the same shape as compression ribs discussed with regard to  FIG. 26 . Although gripping  144  is shown disposed at second end  20 , it can also be disposed at first end  10  or can be disposed in patterns or at spaced apart locations over the entirety of exterior surface  16 . 
     Depicted in  FIG. 32  is another alternative embodiment of a compression collar  10 L. Like elements between compression collar  10 L and other the compression collars disclosed herein are identified by like reference characters. Specifically, compression collar  10 L includes tubular body  12  extending between terminal end face  23  at first end  18  and terminal end face  21  and second end  20 . Tubular body  12  has interior surface  14  that bound throughway  22  and also has exterior surface  16 . Compression collar  10 L is distinguished from compression collar  10 B in the compression collar  10 L does not include spacer tab  24 A. Furthermore, compression collar  10 L includes a window  146 A that extends through tubular body  12  between interior surface  14  an exterior surface  16  at first end  18 . Window  146 A is spaced apart from terminal end face  23  so that window  146   a  is completely encircled by tubular body  12 . In the depicted embodiment, window  146 A is in the form of an elongated slot that extends partially around the circumference of tubular body  12 . However, in other embodiments, window  146 A can be in the form of a circle, ellipse, or other polygonal configurations. 
     Compression collar  10 L functions the same and is used in the same way as compression collar  10 B, previously discussed, except that once tube  40  and tube fitting  42  are coupled together, terminal end face  23  is butted directly against flange  70  of tube fitting  42 . Window  146 A can then be used to ensure that tube  40  is properly positioned within compression collar  10 L. It is appreciated that any desired number of windows  146  can be used and that windows  146  can be disposed at a variety of different locations. For example, in contrast to having a single window  146 A, it is appreciated that 2, 3, 4, or more windows can be disposed extending through tubular body  12  at the same location along the length of tubular body  12 .  FIG. 33  shows such an example where a plurality, more specifically three, of windows  146 A,  146 B, and  146 C are spaced apart and extend through tubular body  12  at the same location along the length of tubular body  12 . Again, windows  146  can be used to ascertain the position of tube  40 . 
     In contrast to windows  146  being disposed at the same location along the length of tubular body  12 , windows  146  can also be spaced apart along the length of tubular body  12 . For example, in  FIG. 34  compression collar  10 L includes first window  146 A and a second window  146 D extending through tubular body  12  so as to be completely encircled by tubular body  12 . However, windows  146 A and  146 D extend through tubular body  12  at two spaced apart locations along the length tubular body  12 .  FIG. 35  show an embodiment of compression collar  10 L which shows a combination of the windows shown in  FIGS. 33 and 34 . Specifically, compression collar  10 L has a first set of a plurality of windows, i.e., windows  146 A and  146 B, that are at a defined location along the length of tubular body  12  and a second set of a plurality of windows, i.e., windows  146 D and  146 E, that are located at a second location along the length of tubular body  12 .  FIG. 36  shows the same embodiment of compression collar  10 L shown in  FIG. 35  except that the first set of a plurality of windows includes three separate windows, i.e., windows  146 A,  146 B and  146 C, while the second set of a plurality of windows includes three windows, i.e., windows  146 D,  146 E, and  146 F. As needed, any desired number of windows can be used at any desired location. 
     Depicted in  FIG. 37  is an alternative embodiment of a compression collar  10 M that can achieve the same function and be used in the same way as the prior compression collars disclosed herein. Like elements between compression collar  10 M and compression collar  10 B are identified by like reference characters. Compression collar  10 M includes tubular body  12  that extends between terminal end face  23  and terminal end face  21  and that bounds throughway  22 . As previously discussed with regard to compression collar  10 B, compression collar  10 M includes an intersection zone  116  that longitudinally extends between terminal end faces  23  and  21  and is where, during the injection molding process, the material used to form compression collar  10 M flows together to form a continuous loop. Weld line  117  can be formed at intersection zone  116  where the material flows together and welds together. As also previously discussed, the material at intersection zone  116  will typically not uniformly blend or mix together so that the lateral tensile strength of the compression collar at intersection zone  116 /weld line  117  is typically less than at other locations around the compression collar. 
     To compensate for this structural weakness, compression collar  10 M is formed having an increased thickness at intersection zone  116 . This increased thickness will typically longitudinally extend between first end  18  and second end  20 . More specifically, a hump  136  is formed on exterior surface  16  of tubular body  12  along intersection zone  116 /weld line  117  that extends between first end  18  and second end  20  and will typically extend between terminal end faces  23  and  21 . Hump  136  is integrally formed with tubular body  12  as part of the molding process so that hump  136  and tubular body  12  form a single, continuous, unitary structure. As a result of hump  136 , the overall hoop strength of compression collar  10 M is increased. In contrast to forming a single continuous hump, in alternative embodiments, two, three, or more spaced apart humps  136  could be formed along intersection zone  116 . 
     In the foregoing alternative embodiments of compression collars, it is appreciated that the inventive compression collars can be formed with a variety of different features and that each feature achieves an independent unique benefit or improvement. In other alternative embodiments, it is appreciated that each of the independent features previously discussed can be mixed and matched into any desired combination. For example, alternative compression collars can be formed that include tubular body  12  and that can further include zero or one or more spacer tabs  24 , zero or one or more stop lips  32 , zero or one or more annular compression ribs  120 , zero or one or more non-annular compression ribs  124  and/or  126 , zero or one or more retention ribs  140 , zero or one or more gripping  144 , zero or one or more windows  26  and/or  146 , and/or zero or one or more humps  136 . By way of example and not by limitation, depicted in  FIG. 38  is an alternative embodiment of a compression collar  10 N that includes tubular body  12  having spacer tab  24 A, compression ribs  122 A- 122 C and retention rib  140  formed thereon. Again, compression collars can also be formed having tublar body  12  and any combination of the above described features or alternatives of the above described features. 
     As previously discussed with regard to  FIGS. 7-8B , expander  80  can be used to selectively expand compression collars  10 . In the previously discussed method for expansion, a single expander  80  is inserted into one end of a compression collar  10  for expansion of the compression collar. In one alternative method of expansion, dual expanders  80  can be inserted into the opposing ends of a compression collar  10  to simultaneously expand the compression collar  10  at both opposing ends. This method can be helpful in retaining interior surface  14  more circular as compression collar  10  is expanded. 
     It is also appreciated that the expander can come in a variety of different configurations. For example, depicted in  FIGS. 39 and 40  is one alternative example of an expander  150 , in the form of a mandrel, that can be used for expanding compression collars  10 . Expander  150  has a first end  152  and an opposing second end  154  with a central longitudinal axis  155  extending through the opposing ends. Expander  150  includes an annular tapered body  156  that outwardly flares from first end  152  toward second end  154 . A plurality of elongated, cylindrical rollers  158  are rotatably mounted on tapered body  156 . Rollers  158  are radially spaced apart around tapered body  156  and extend along the length to tapered body  156  so that roller  158  also outwardly flare or project as they extend from first end  152  toward second end  154 . Furthermore, rollers  150  are laterally sloped at an angle θ relative to central longitudinal axis  155 . Angle θ is typically at least or less than 5°, 10°, 15°, 20°, 30°, 40° or in a range between any two of the foregoing. Other angles can also be used. Body  156  terminates at a tapered nose  160  at first end  152 . Coupled with body  156  at second end  154  is a shank  162 . Shank is configured to engage with a drill such as a hand drill or a drill press and typically has a cylindrical or polygonal transverse cross section. 
     During use, nose  160  is advanced into throughway  22  from one end of a compression collar  10 . Compression collar  10  is held stationary while expander  150  is rotated. As rotating expander  150  is advanced into throughway  22 , rollers  158  ride against and rotate over interior surface  14 . Because of the outward projection or flare of rollers  158 , rollers  158  radially outwardly expand compression collar  10  as expander  150  is pressed further into throughway  22 . Furthermore, because rollers  158  are rolling over interior surface  14 , rollers  158  produce low friction and do not damage compression collar  10 . Expander  80  is advanced until compression collar  10  is sufficiently expanded to facilitate coupling with tube  40  and tube fitting  42 , as previously discussed. If desired, separate expanders  150  can simultaneously advance into throughway  22  of compression collar  10  from the opposing ends for expansion. Likewise, expander  150  can be inserted consecutively into the opposing ends of compression collar  10  for expansion. 
     In contrast to laterally angling rollers  158  relative to longitudinal axis  155 , as shown in  FIG. 39 , rollers  158  can also be aligned with longitudinal axis  155 . For example,  FIG. 41  shows an alternative expander  150 A that is substantially identical to expander  150  except that rollers  150  are all aligned with longitudinal axis  155 . Expander  150 A can be used in the same way as expander  150  as discussed above. 
     Depicted in  FIGS. 42-44  is a further alternative embodiment of an expander  170  that can be used to expand any of the compression collars disclosed herein. Expander  170  comprises an elongated tubular stem  172  having a channel  173  extending between a first end  174  and an opposing second end  176 . Channel  173  is open at first end  174  but is sealed closed at second end  176 . Stem  172  is typically made of a rigid material like a metal. A pump  178  is couple with first end  174  and is used to deliver hydraulic fluid into channel  173  of stem  172 . 
     A tubular bladder  180  is disposed on and encircles stem  172 . Bladder  180  has a first end  182  and an opposing second end  184 . A clamp  186  securely fixes second end  184  of bladder  180  to second end  176  of stem  172  and forms a liquid tight seal therebetween. A clamp  188  is also disposed at first end  182  of bladder  180 . Clamp  188 , however, does not securely fix first end  182  of bladder  180  to stem  172 . Rather, clamp  188  forms a liquid tight seal between first end  182  of bladder  180  and stem  172  but still permits first end  182  of bladder  180  to slide along stem  172 . As needed, a gasket or other type of seal can be disposed between bladder  180  and stem  172  which assists in effecting the movable liquid tight seal. Bladder  180  is made of a resiliently expandable material. 
     A compartment  190  is formed between stem  172  and bladder  180  and is sealed closed on opposing ends by clamps  186  and  188 . One or more openings  192  pass through stem  172  and provide fluid communication between channel  173  and compartment  190 . 
     During use, a compression collar is slid over bladder  180  so as to encircle bladder between clamps  186  and  188 . Hydraulic fluid is then pumped by pump  178  into channel  173  of stem  172 . The hydraulic fluid passes through opening  192  and into compartment  190 . As the pressure of the hydraulic fluid increases, bladder  180  radially outwardly expands causing the compression collar to expand from the contracted state to the expanded state. To accommodate for the expansion of bladder  180 , first end  182  of bladder  180  slides toward second end  184  as bladder  180  expands. In this assembly, the central portion of bladder  180 , which is encircled by the compression collar, expands in a substantially cylindrical configuration, thereby providing uniform expansion of the compression collar. Once the compression collar has moved to the expanded state, the pressure on the hydraulic fluid is released. Bladder  180  then resiliently retracts to its unexpanded state and the compression collar is removed for attachment. As a result of balder  180  being flexible, the use of bladder  180  limits damage to the compression collar as the compression collar is expanded to the expanded state. 
     The inventive compression collars achieve a number of unique benefits. For example, because of the design and manufacturing process, the compression collars have rounded corners and are void of sharps both prior to and after attachment to tube  40  and tube fitting  42 . As such, the compression collars provide minimal risk of damage to adjacent structures, such as polymeric bag or tubes, even when folded together. As such, minimal or no special packaging may be required to be applied around the compression collars, thereby minimizing manufacturing time and cost. 
     Furthermore, in contrast to traditional cable ties, the compression collar provides a uniform and constant compressive force entirely around the tube fitting. As such, there is a less chance for leakage or contamination passing between tube  40  and tube fitting  42 , even when tube  40  is being moved. In addition, the compression collars provide a secure engagement between tube  40  and tube fitting  42 , thereby preventing any unwanted or accidental separation or leaking between tube  40  and tube fitting  42 . This secure engagement can potentially be further enhanced by the application of radiation to the compression collars after the compression collars have resiliently rebounded from the expanded state. Furthermore, in contrast to cable ties, the compression collars are easy to attach and guarantee a more consistent compressive force that is less subject to errors produced by those assembling the systems. In part, this is because the inventive compression collars are wider than cable ties, thereby compressing tube  40  over a longer length of tube fitting  42  which improves the sealed engagement. In addition, unlike cable ties which can relax their compressive force over time, the compression collars will maintain their compressive force over time. The compression collars can also provide a higher compressive force than cable ties. The windows  26 ,  146 , spacer tabs  24 , and/or stop lips  32  also provide unique advantages of both ensuring and being able to confirm that the coupled tube fitting  42  and tube  40  are properly positioned within the compression collars for proper compression and sealing therebetween. Other advantages also exist. 
     Although the compression collars depicted herein achieve functional benefits, they are also designed to have aesthetic attributes. For example, the compression collars are provide curved lines and symmetry that provide a unique aesthetic appeal to the compression collars. 
     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.