Abstract:
An end fitting for a tube housed by a cavity and a method of installing a tube in a cavity are described which use a compression ring that defines a void having an axial extent and a radial extent. The compression ring is compressed between a bracket of the end fitting and a port of the cavity by drawing the bracket axially towards the port. This seals the port and deforms the void defined by the compression ring. The deformation of the void reduces its axial extent and increases its radial extent, thereby compressing the tube against an insert received within the interior of the tube.

Description:
BACKGROUND 
       [0001]    Peristaltic pumps are commonly used for applications in which it is undesirable for a pumped fluid to contact pump components. For example, peristaltic pumps are often used to pump sterilized or abrasive fluids where contact of the fluid with internal pump components would risk contaminating the fluid or damaging the pump. Peristaltic pumps are therefore often used in the food industry in which sterile pumping processes are required and in the aggregates industry in which slurries containing abrasive particles need to be transferred. 
         [0002]    Peristaltic pumps generally comprise a pump housing, a rotor assembly arranged within the pump housing, and a flexible tube disposed between the pump housing and the rotor assembly. The rotor assembly typically comprises a pair of pressing shoes which, when the rotor assembly is rotated, move along the tube to exert a peristaltic action on the tube. 
         [0003]    Suction and discharge lines (typically, rigid in construction) are coupled to the tube via a pair of ports provided in the pump housing. The coupling of the suction and discharge lines to the tube must be fluid-tight to avoid any leakage of the pumped fluid. 
         [0004]    In order to reduce the amount of wear on the tube and the pressing shoes and to dissipate heat, particularly where high operating pressures are required (often using reinforced hoses—such pumps being referred to as hose pumps), it is often desirable to provide a lubricating fluid within the pump housing. At the ports in the pump housing, it is therefore necessary to seal the tube against the pump housing to prevent the lubricating fluid from leaking out of the pump housing. 
         [0005]    As described, the tube must therefore be sealed against the pump housing to avoid leakage of lubricating fluid and also sealed with the suction and discharge lines to avoid leakage of pumped fluid.  FIGS. 1 and 2  show two examples of known end fittings which achieve such sealing. 
         [0006]    In the example of  FIG. 1 , the end fitting comprises a rubber bush  1  which is received over the end of the tube (not shown). A bracket  3  is received over the bush  1  and connected to a port of the pump housing, such that a flange of the bush  1  is sandwiched between the bracket  3  and the port. The flange of the bush  1  seals against the pump housing to prevent lubricating fluid from leaking out of the pump housing. 
         [0007]    A hose clamp  5  is received over the bush  1  with the tube disposed therein. 
         [0008]    A flange  7  is connected to the bracket  3  and an insert  9  is located in an opening passing through the flange  7 . The insert  9  extends through the flange  7  and into the interior of the tube. The hose clamp  5  is then tightened to seal the tube against the insert  9 . 
         [0009]    As shown in  FIG. 2 , the bush  1  may be replaced by an O-ring  11 . Essentially, the O-ring  11  serves the same purpose as the bush  1  and seals against the pump housing to prevent lubricating fluid from leaking out of the pump housing. 
         [0010]    As well as their sealing functions, the end fittings shown in  FIGS. 1 and 2  also fasten the tube in position and thus provide strain relief against the movement of the rotor. 
         [0011]    Although the end fittings shown in  FIGS. 1 and 2  provide adequate sealing properties, they can be somewhat difficult and time-consuming to assemble. Moreover, the end fittings may be incorrectly assembled resulting in leakage of the pumped fluid and/or lubricating fluid, and/or poor performance of the pump caused by air intake at the suction port. 
       SUMMARY 
       [0012]    According to an aspect of the invention, there is thus provided an end fitting for a tube housed by a cavity, the end fitting comprising: a bracket having a first abutment shoulder which opposes a port of the cavity; a compression ring disposed against the first abutment shoulder of the bracket and configured to receive the tube therethrough, the compression ring defining a void having an axial extent and a radial extent; an insert configured to be received within the interior of the tube such that the insert overlaps and extends beyond the compression ring; and a fastener for connecting the bracket to the port so as to draw the bracket axially towards the port, whereby the compression ring is compressed between the first abutment shoulder and the port so as to seal the port and such that the void defined by the compression ring is deformed; wherein the deformation of the void reduces its axial extent and increases its radial extent, thereby compressing the tube against the insert. 
         [0013]    The compression ring may have an inner diameter which, in an at-rest configuration, is greater than or substantially equal to an outer diameter of the tube, and which, in a compressed configuration, is less than the outer diameter of the tube. 
         [0014]    The cavity may be defined by a pump housing of a peristaltic pump. 
         [0015]    The void may be defined by the cross-section of the compression ring and may be located between the compression ring and the tube, bracket, and/or port. 
         [0016]    The cross-section of the compression ring may define one or more annular channels. 
         [0017]    The cross-section of the compression ring may define a plurality of annular channels spaced axially from one another. 
         [0018]    The cross-section of the compression ring may define a plurality of annular channels oriented in different directions with respect to one another. 
         [0019]    The void may be located within the cross-section of the compression ring. 
         [0020]    The compression ring may be hollow. 
         [0021]    The compression ring may be formed by a foam material having pores which define a plurality of voids. 
         [0022]    The bracket may comprise an annular portion which is configured to receive the tube therein. 
         [0023]    The annular portion may have a second abutment shoulder against which the tube abuts. 
         [0024]    An opening may be provided through the annular portion, the opening being located adjacent the second abutment shoulder. 
         [0025]    The insert may comprise an axial portion which is configured to be received within the interior of the tube. The insert may further comprise one or more projections which extend radially from the axial portion. The diameter of the one or more projections may be greater than the inner diameter of the tube, and the diameter of the remainder of the axial portion may be less than the inner diameter of the tube. 
         [0026]    The axial portion may be received by the annular portion of the bracket. The annular portion may thus guide the insertion of the insert into the tube. 
         [0027]    The insert may comprise an end portion which abuts the bracket. 
         [0028]    The end portion of the insert may be a flange portion which abuts a corresponding flange portion of the bracket. The flange portion of the bracket may be configured to allow the bracket to be connected to a discharge or suction line. 
         [0029]    The bracket may comprise an inner (flange) portion which abuts against a surface of the port so as to limit the compression of the compression ring. 
         [0030]    The bracket may comprise a tongue or groove which is received by or receives a corresponding groove or tongue of the port. 
         [0031]    The tongue and groove may be annular, the tongue housing the compression ring. 
         [0032]    According to another aspect of the invention, there is provided a peristaltic pump comprising an end fitting as described previously. 
         [0033]    According to another aspect of the invention, there is provided method of installing a tube in a cavity, the method comprising: locating the tube within the cavity such that an end of the tube projects out of a port of the cavity; placing a compression ring and a bracket over the end of the tube such that the compression ring is disposed between a first abutment shoulder and the port, the compression ring defining a void having an axial extent and a radial extent; placing an insert within the interior of the tube such that the insert overlaps and extends beyond the compression ring; and drawing the bracket axially towards the port, thereby compressing the compression ring between the first abutment shoulder and the port so as to seal the port and deform the void defined by the compression ring; wherein the deformation of the void reduces its axial extent and increases its radial extent, thereby compressing the tube against the insert. 
         [0034]    Drawing the bracket axially towards the port may comprise a first compression stage in which the void reduces its axial extent and increases its radial extent, thereby compressing the tube against the insert, and a second compression stage in which the material of the compression ring is compressed to seal the compression ring against the bracket and the port. 
         [0035]    Drawing the bracket axially towards the port may comprise drawing the bracket towards the port until an inner flange of the bracket abuts against a surface of the port. 
         [0036]    For a better understanding of the present disclosure, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:— 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]      FIG. 1  is an exploded view of an example of a prior art end fitting; 
           [0038]      FIG. 2  is an exploded view of another example of a prior art end fitting: 
           [0039]      FIG. 3  is a cross-sectional view of an end fitting according to an embodiment of the invention, the end fitting being shown in a first stage of assembly; 
           [0040]      FIG. 4  is a cross-sectional perspective view of a compression ring of the end fitting of  FIG. 3 ; 
           [0041]      FIG. 5  is a cross-sectional view of an insert of the end fitting of  FIG. 3 ; 
           [0042]      FIG. 6  is an enlarged view of an end portion of the insert showing two possible configurations; 
           [0043]      FIG. 7  is a cross-sectional view of the end fitting in a second stage of assembly; 
           [0044]      FIG. 8  is a cross-sectional view of the end fitting in a third stage of assembly; 
           [0045]      FIGS. 9 and 10  show examples of alternative cross-sections of the compression ring; and 
           [0046]      FIGS. 11 and 12  show exploded views of the end fitting with an additional adaptor member which can be used to retrofit the end fitting to an existing pump. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]      FIG. 3  shows an end fitting  2  according to an embodiment of the invention which is configured to connect to a (suction or discharge) port  4  provided in a pump housing of a peristaltic pump. 
         [0048]    The end fitting  2  comprises a bracket  6 . The bracket  6  comprises a generally cylindrical axial portion  8  and outer and inner flange portions  10   a ,  10   b  which extend perpendicularly from either end of the axial portion  8  in a radial direction. 
         [0049]    The axial portion  8  is formed by a first section  8   a  and a second section  8   b  which are stepped relative to one another. The first section  8   a  thus has an internal diameter d 1  which is smaller than the internal diameter d 2  of the second section  8   b.    
         [0050]    An annular tongue  12  projects from an inner surface of the inner flange portion  10   b . The inner surface of the annular tongue  12  is stepped back from the inner surface of the second section  8   b  of the axial portion  8 . The second section  8   b  thus has an internal diameter d 2  which is smaller than the internal diameter d 3  of the annular tongue  12 . 
         [0051]    As described, the first and second sections  8   a ,  8   b  of the axial portion  8  and the annular tongue  12  are stepped relative to one another such that a first radial abutment surface  14   a  (second abutment shoulder) is formed between the first and second sections  8   a ,  8   b  of the axial portion  8 , and a second radial abutment surface  14   b  (first abutment shoulder) is formed between the second section  8   b  of the axial portion  8  and the annular tongue  12 . 
         [0052]    A compression ring  16  is disposed radially inboard of the annular tongue  12  and abuts the second radial abutment surface  14   b . The compression ring  16  is formed of a flexible elastomeric material. As shown in  FIG. 4 , the compression ring  16  has a substantially U-shaped cross-section (which may also be described as C-shaped or semicircular) which is arranged such that an annular channel  18  defined by the U-shaped cross-section is directed radially outwardly. The axial extent of the annular tongue  12  is greater than the width of the compression ring  16 , such that a portion of the annular tongue  12  projects past the compression ring  16 . 
         [0053]    As shown in  FIG. 3 , the annular channel  18  of the compression ring  16  faces the annular tongue  12 . The compression ring  16  is sized relative to the second radial abutment surface  14   b  so that, in its at-rest configuration, the radially innermost surface of the compression ring  16  is substantially level with the inner surface of the second section  8   b  of the axial portion  8 . In other words, the inner diameter of the compression ring  16  is substantially equal to the internal diameter d 2  of the second section  8   b . The compression ring  16  may, however, sit slightly proud of or slightly below the level of the inner surface of the second section  8   b.    
         [0054]    The inner flange portion  10   b  of the bracket  6  is provided with a number of openings spaced around its circumference which each receive a bolt  20  (and washer). The outer flange portion  10   a  of the bracket  6  may also be provided with a number of openings (now shown) spaced around its circumference for attaching the bracket to a discharge or suction line. 
         [0055]    An end surface of the port  4  is provided with an annular groove  22  which is sized to receive the annular tongue  12  of the bracket  6 . The annular groove  22  encircles the opening of the port  4  which is defined by a cylindrical inner surface  24  of the pump housing. The annular groove  22  divides the end surface of the port  4  into an inner radial abutment surface  26   a  and an outer radial abutment surface  26   b . The inner radial abutment surface  26   a  is recessed below the level of the outer radial abutment surface  26   b  and has a conical taper. The conical taper may assist with the loading of a tube in the pump housing. The conical taper may also assist in releasing the compression ring  16  during disassembly. 
         [0056]    The port  4  is provided with a plurality of threaded bores  28  which are spaced around the circumference of the port  4  and pass through the outer radial abutment surface  26   b.    
         [0057]    During a first stage of assembly, a tube  30  of the peristaltic pump is located within the pump housing. This may be achieved by introducing the tube  30  into the pump housing via one of the ports  4  and rotating a rotor of the pump to draw the tube  30  through the pump housing. 
         [0058]    To allow a shoe of the rotor to grip the tube  30  and avoid the rotor slipping relative to the tube  30 , an enlarged collar may be provided on one end of the tube  30 . Accordingly, for a conventional hose-pump (C-shape) having a rotor with two shoes, it takes just a little more than half a revolution of the rotor to fully insert the tube  30  into the pump. This may be particularly beneficial where the pump operates at low speeds or where the rotor is rotated by hand to introduce the tube (and to pump the fluid). 
         [0059]    The tube  30  is sufficiently long so that when it is inserted into the pump housing it projects a small distance from the port  4 . The bracket  6  is then introduced over one end of the tube  30  and the annular tongue  12  of the bracket  6  is received by the annular groove  22  of the port  4  so that the inner radial abutment surface  26   a  of the port  4  opposes the second radial abutment surface  14   b  of the bracket  6 , with the compression ring  16  disposed therebetween. 
         [0060]    The bolts  20  pass through the openings in the inner flange portion  10   b  and engage in the threaded bores  28  to connect the bracket  6  to the port  4 . The bolts  20  are tightened so as to draw the first radial abutment surface  14   a  of the bracket  6  into abutment with the end of the tube  30 . As described previously, the compression ring  16  is substantially flush with the second radial abutment surface  14  when in its at-rest configuration. The tube  30  is therefore able to easily slide through the compression ring  16  and into second section  8   b  of the axial portion  8 . The tightening of the bolts  20  also draws the annular tongue  12  of the bracket  6  towards and into the annular groove  22  of the port  4 , and the second radial abutment surface  14   b  of the bracket  6  toward the inner radial abutment surface  26   a  of the port  4 . 
         [0061]    The bolts  20  are sufficiently long so that they initially engage in the threaded bores  28  without the inner radial abutment surface  26   a  of the port  4  coming into contact with the compression ring  16  (or at least not sufficiently to deform the compression ring  16  from its at-rest configuration). However, the portion of the annular tongue  12  which projects past the compression ring  16  is received in the annular groove  22 . 
         [0062]    With the tube  30  in abutment with the first radial abutment surface  14   a , but with the compression ring  16  still in its at-rest configuration, an insert  32  is inserted into the bracket  6 . As shown particularly in  FIG. 5 , the insert  32  comprises an axial portion  34  and a flange portion  36  which extends perpendicularly from the axial portion  34  in a radial direction. 
         [0063]    The axial portion  34  of the insert  32  passes through the axial portion  8  of bracket  6  and into the interior of the tube  30 , with the flange portion  36  of the insert  32  abutting the outer flange portion  10   a  of the bracket  6 . The axial portion  8  of the bracket  6  thus guides the axial portion  34  of the insert  32  into the tube  30 . The axial portion  34  of the insert  32  is sufficiently long so that it projects past the compression ring  16 . 
         [0064]    The cross-section of the axial portion  34  of the insert  32  is substantially uniform along its length and has a constant outer diameter, di, across its length. The outer diameter di may be substantially equal to or slightly larger than an inner diameter, dt, of the tube  30 . 
         [0065]    However, as shown in  FIG. 6 , at the free end of the axial portion  34  (i.e. the end spaced from the flange portion  36 ), one or more projections  38  may be formed which have a diameter that is greater than the remainder of the axial portion  34 . For example, in  FIG. 6( a ) , an enlarged collar  38   a  is provided around the axial portion  34 , whereas, in  FIG. 6( b ) , a series of radially extending barbs  38   b  are provided around the axial portion  34 . The projections  38  are, however, only provided over a small proportion of the axial portion  34  which may amount to less than 10% of the total length of the axial portion  34 . 
         [0066]    In this case, the outer diameter di of the axial portion  34  of the insert  32  may be slightly less than the inner diameter dt of the tube  30  and the projections  38  may have a diameter which is greater than the inner diameter dt of the tube  30 . Alternatively, both the outer diameter di of the axial portion  34  of the insert  32  and the diameter of the projections  38  may be substantially equal to or slightly larger than the inner diameter dt of the tube  30 . Accordingly, the projections  38  provide some resistance to the insertion of the axial portion  34  of the insert  32  into the interior of the tube  30 . The resistance is not, however, sufficient to cause the tube  30  to be pushed into the pump housing during the insertion of the insert  32 . 
         [0067]    As shown in  FIGS. 5 and 6 , an internal taper  40  is also provided at the free end of the axial portion  34  of the insert  32  to guide the pumped fluid from the tube  30  into the insert  32  or from the insert  32  into the tube  30 . 
         [0068]    With the insert  32  in place, the bolts can be further tightened so as to draw the second radial abutment surface  14   b  of the bracket  6  further toward the inner radial abutment surface  26   a  of the port  4 . As shown in  FIG. 7 , this causes the compression ring  16  to compress and deform. 
         [0069]    The compression of the compression ring  16  in the axial direction causes the radial extent of the compression ring  16  to increase. This is effected by the annular channel  18 . The inner surface of the annular channel  18  has a constant surface area and thus any change in axial extent is necessarily converted into a corresponding change in radial extent. Moreover, as the compression ring  16  is supported by the annular tongue  12 , the increase in the radial extent of the compression ring  16  is realized as a reduction in the inner diameter of the compression ring  16 . Specifically, the inner diameter of the compression ring  16  becomes smaller than the internal diameter d 2  of the second section  8   b  and, importantly, smaller than the outer diameter of the tube  30 . 
         [0070]    In this first stage of compression, opposing portions of the inner surface of the annular channel  18  are forced toward one another to reduce the axial extent of the compression ring  16  and to increase the radial extent of the compression ring  16 . In other words, the compression ring  16  is deformed in shape, but the material itself is not significantly compressed. 
         [0071]    As described previously, the axial portion  34  of the insert  32  overlaps and extends beyond the compression ring  16 . The deformation of the compression ring  16  thus forces the tube  30  against the axial portion  34  of the insert  32 . Consequently, the compression ring  16  locks the position of the tube  30  and insert  32  relative to one another, and relative to the port  4  and the bracket  6 . The axial portion  34  of the insert  32  extends sufficiently past the compression ring  16  and the inner radial abutment surface  26   a  so as to ensure that the insert  32  is not pushed outward during compression of the compression ring  16 . However, the axial portion  34  of the insert  32  is short enough to ensure that the tube  30  makes a smooth transition onto the axial portion  34 . In other words, the tube  30  seals (where it is compressed by the compression ring  16 ) as close as possible (taking into account the competing consideration described above) to the end of the axial portion  34 . This improves hygiene since the pumped fluid is prevented from collecting between the tube  30  and the axial portion  34  in a region inward of the compression ring  16 . 
         [0072]    As shown in  FIG. 8 , the bolts are further tightened until the inner flange portion  10   b  abuts the outer radial abutment surface  26   b . This provides tactile feedback to the user to confirm that sufficient compression has been applied. The compression of the compression ring  16  is thus determined by the extent to which the inner radial abutment surface  26   a  is recessed below the level of the outer radial abutment surface  26   b . This is configured to place the compression ring  16  under sufficient compression to achieve adequate sealing, whilst avoiding the compression ring  16  from becoming overstressed. 
         [0073]    Following the first stage of compression, the opposing portions of the inner surface of the annular channel  18  have already been forced into contact with one another. Therefore, in this second stage of compression, the further compression of the compression ring  16  causes the material of the compression ring  16  itself to be compressed. 
         [0074]    Although the compression ring  16  has been described as being oriented so that the annular channel  18  faces radially outward toward the annular tongue  12 , other orientations may be used. In particular, the compression ring  16  may be oriented so that the annular channel  18  faces the tube  30 , the second radial abutment surface  14   b  of the bracket  6  or the inner radial abutment surface  26   a  of the port  4 . 
         [0075]    Further, although the compression ring  16  has been described as having a U-shaped cross-section, many other forms of compression ring  16  may be used. 
         [0076]    For example, as shown in  FIG. 9 , instead of the single annular channel  18  described previously, the compression ring may define a plurality of annular channels spaced axially from one another. Specifically,  FIG. 9( a )  shows a compression ring having two annular channels, whereas  FIG. 9( b )  shows a compression ring having three annular channels. 
         [0077]    The cross-sectional shape of the compression ring  16  may also differ significantly, as shown in  FIG. 10 . For example, the cross-sectional shape of the compression ring  16  may be more angular, as shown in  FIG. 10( a ) . The cross-section of the compression ring  16  may also be X, Y, T, O or P-shaped, as shown in  FIGS. 10( b )-( f ) . As shown in  FIGS. 10( g ) and ( h ) , the compression ring  16  may also be formed from an open or closed-cell foam having a circular or square cross-section. 
         [0078]    However, in all of the examples, the compression ring  16  defines one or more voids having an axial extent and a radial extent. In the O and P-shaped examples (see  FIGS. 10( e ) and ( f ) ) a void is defined within the cross-section of the compression ring  16 . Similarly, where the compression ring  16  is formed from a foam material, the voids are formed by the pores of the material itself. On the other hand, in the U, X, Y and T-shaped examples, one or more voids are formed between the compression ring  16  and the port  4 , bracket  6  and/or tube  30 . Regardless of the formation of the one or more voids, the flexible nature of the compression ring allows the axial extent of the void to be reduced through compression of the compression ring  16 . This, in turn, results in an increase in the radial extent of the compression ring  16 , thus providing the required sealing and fixation. The void magnifies the increase in the radial extent of the compression ring  16  when compared with the deformation of conventional O-rings. Accordingly, the compression ring  16  can have a smaller cross-section and still achieve the same increase in radial extent. 
         [0079]    Although not shown, one or more radial openings may be provided through the second section  8   b  of the axial portion  8  in the region of the first radial abutment surface  14   a . Such openings may be used to visually confirm that the tube  30  is properly seated against the first radial abutment surface  14   a  both before and after the bracket  6  is screwed onto the port  4  to deform the compression ring  16 . For example, a pair of radial openings may be provided which are diametrically opposed from one another and thus provide visual access to the tube  30  from either direction. 
         [0080]    The tube  30  may also project from the bracket  6  or be exposed within the bracket  6  to allow a conventional hose clamp to fastened to the tube  30  (in a similar manner to the hose clamp  5  used in the examples of  FIGS. 1 and 2 ). This may help to retain the tube  30  in place where the pump is to be used in particularly extreme situations (e.g. mining) or where the tube has a particularly large diameter. 
         [0081]    The bracket  6  may be connected to the port  4  using alternative means instead of the bolts  20 . For example, other types of fasteners may be used to effect axial movement of the bracket  6  relative to the port  4 . Further, the bracket  6  and port  4  may be threadedly engaged with one another such that rotation of the bracket  6  relative to the port  4  causes the bracket  6  to translate axially relative to the port  4 . This may obviate the need for the inner flange portion  10   b.    
         [0082]    The compression ring  16  may simply be placed over the tube  30  during assembly and need not be carried by the bracket  6 , as described previously. The compression ring  16  could alternatively be coupled to the port  4  such that the tube  30  is received through the compression ring  16  when it enters or exits the port  4 . The bracket  6  must, however, have a suitable abutment shoulder which cooperates with the port to force the compression ring  16  radially inwards to clamp the tube  30 . 
         [0083]    The annular tongue  12  may be provided at the port  4  rather than the bracket  6 , and the annular groove  22  may be provided as part of the bracket  6  rather than the port  4 . Moreover, the annular tongue  12  and groove  22  need not be annular. The tongue and groove may instead be formed by a plurality of discrete interlocking tongue and groove elements. For example, each tongue and groove element may define a projection or a recess having a circular arc. This may be particularly beneficial where the bracket  6  must be positioned in a fixed orientation relative to the port  4 . Further, such an arrangement is still able to retain the compression ring  16  in the correct position. 
         [0084]    The bracket  6  and insert  32  may be coupled to one another using arrangements other than via the abutting flange portions. In particular, the bracket  6  and/or insert  32  need not be provided with a flange portion. It is, however, beneficial for the bracket  6  and/or insert  32  to have some arrangement which limits the depth to which the insert  32  can be inserted. Yet, this may be provided by one or more protrusions or tabs extending radially from the insert  32  or by a local thickening of the insert  32 . 
         [0085]    Although the tube  30  has been described as such, it may instead be a hose. Further, the bracket  6  and insert  32  may be integrally formed with one another such that the tube  30  is received between the bracket  6  (specifically, the second section  8   b  of the axial portion) and the insert  32  (specifically, the axial portion  34 ). 
         [0086]    The end fitting  2  described herein may be retrofit to existing pumps via a simple adaptor member  42 , as shown in  FIGS. 11 and 12 . In such existing pumps, the port  4 ′ may have a flat end surface against which a conventional end fitting abuts via threaded bores provided in the port  4 ′. The adaptor member  42  therefore provides the features described previously, such as the annular groove  22 , etc. and thus convert the port  4 ′ into the port  4 . The adaptor member  42  is affixed to the port  4 ′ using the conventional threaded bores of the port  4 ′. A rear surface of the adaptor member  42  is provided with an annular groove  44 . The annular groove  44  receives a conventional O-ring  46  which is disposed between the adaptor member  42  and the port  4 ′ to provide a seal therebetween. 
         [0087]    Although the end fitting  2  has been described with reference a peristaltic pump, it may also be used in other applications in which a tube passes through a cavity and sealing is required with the tube and between the tube and the cavity. For example, the end fitting  2  could be used in a similar manner with a pulsation dampener which may be employed to reduce the pulses created in the discharge line of a peristaltic pump. Such a pulsation dampener may comprise a hose which passes through a pressure vessel containing a compressed gas, such as air or nitrogen. The pressure vessel must therefore be sealed against the hose to prevent the compressed gas from exiting the pressure vessel. The hose is connected to the discharge line and again this must be a fluid tight seal to avoid leakage of the pumped fluid. The end fitting  2  of the invention could thus be employed in a similar manner to that described previously to provide such sealing. Other applications will also be apparent to those skilled in the art. 
         [0088]    The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention.