Patent Publication Number: US-2009236851-A1

Title: Coupling arrangement

Description:
The present invention relates to a coupling arrangement for use with flexible fluid lines, such as garden hoses. It will be convenient to describe the invention in relation to its use with garden hoses, although it should be appreciated that the invention can be employed in flexible fluid lines used for other purposes. 
     A popular form of connection between a hose and hose fittings employs click or snap connectors. While such connectors are easy to use, they typically are of relatively complex construction including several moving parts, so that they are relatively expensive to manufacture and are susceptible to damage or failure upon ingress of foreign matter such as soil. 
     International application WO91/00469 discloses a fluid line coupling developed by one of the inventors of the present application. That coupling includes two interconnecting parts, one of which is connectable to a fluid line and the other to either of a fluid supply or discharge facility. Drawbacks associated with this type of coupling is that the interconnecting parts are quite separate and include no common parts while it provides no interface with the popular form of snap-fit discharge nozzle which is so popular throughout the world. Thus, the coupling was usually only able to be coupled to a fluid discharge facility, i.e. a tap. 
     International application WO 98/41791 discloses a hose coupling having similar drawbacks to WO 91/00469 discussed above. Thus, the hose coupling of this reference requires a different connection to each of a fluid supply or discharge facility or a hose while, additionally, the sealing arrangement between the connectable coupling parts of the hose coupling is prone to leakage. 
     It is an object of the present invention to provide a coupling arrangement preferably for a flexible fluid line which is an improved coupling compared to prior art couplings. 
     In a broad form of the invention there is provided a coupling arrangement including a first coupling and a second coupling, the first and the second couplings being connectable together to form a joint, each of the first and second couplings defines a passage through which fluid can flow, and in a connected condition of the first and second couplings, the respective passages are in alignment to allow flow of fluid through the joint, each of the first and second couplings includes first and second interconnecting coupling parts, in which the first coupling part defines the passage of the coupling, the second coupling part of each coupling is connectable to the first coupling part of the coupling with which it is associated, and to the first coupling part of the other coupling of the joint, the first and second couplings are coupled together by releasable connection between the second coupling part of each coupling with the first coupling part of the mating coupling. 
     In a more specific form of the invention there is provided a coupling arrangement for coupling a flexible fluid line between a fluid supply facility or a fluid discharge facility, the coupling arrangement includes a first coupling which is connectable to the fluid supply facility or to the fluid discharge facility, and a second coupling which is connectable to an opposite end of the flexible fluid line, the first and the second couplings are connectable together to form a joint, each of the first and second couplings defines a passage through which fluid can flow, and in a connected condition of the first and second couplings, the respective passages are in alignment to allow flow of fluid through the joint, each of the first and second couplings includes first and second interconnecting coupling parts, in which the first coupling part defines the passage of the coupling, the first coupling part of the first coupling is connectable to one of the fluid supply or fluid discharge facilities, the second coupling part of each coupling is connectable to the first coupling part of the coupling with which it is associated, and to the first coupling part of the other coupling of the joint, the first and second couplings are coupled together by releasable connection between the second coupling part of each coupling with the first coupling part of the mating coupling. 
     In a still more specific form of the invention there is provided a coupling arrangement for coupling a flexible fluid line between a fluid supply facility and a fluid discharge facility. In above forms of the invention, the fluid supply facility can be a domestic garden tap for example, while the fluid discharge facility can be a spray nozzle or water sprinkler. The coupling arrangement includes a flexible fluid line between a fluid supply facility and a fluid discharge facility, the coupling arrangement includes a first coupling which is connectable to the fluid supply facility and to the fluid discharge facility, and a second coupling which is connectable to opposite ends of the flexible fluid line, the first and the second couplings are connectable together to form a joint, each of the first and second couplings defines a passage through which fluid can flow, and in a connected condition of the first and second couplings, the respective passages are in alignment to allow flow of fluid through the joint, each of the first and second couplings includes first and second interconnecting coupling parts, in which the first coupling part defines the passage of the coupling, the first coupling part of the first coupling is connectable to one of the fluid supply or fluid discharge facilities, the second coupling part of each coupling is connectable to the first coupling part of the coupling with which it is associated, and to the first coupling part of the other coupling of the joint, the first and second couplings are coupled together by releasable connection between the second coupling part of each coupling with the first coupling part of the mating coupling. 
     By the above arrangement, the second coupling parts of the first and second couplings of each joint can be of the same construction, or in other words, the second coupling parts can be a universal part regardless of whether it is associated with the first or second coupling. This is advantageous in relation to minimising the complexity of the couplings and the cost of manufacture, and reducing the overall number of parts required for couplings that connect to a fluid supply facility and to a fluid discharge facility. In this latter respect, it will become apparent from the discussion which follows that a significant advantage is provided by the invention compared to prior art couplings. For example, in a common domestic system, in which a hose is attached to a tap at one end and to a spray nozzle at the other end, a coupling arrangement of the invention can be applied so that the first coupling of each joint attaches respectively to the tap and the nozzle, and the second coupling attaches to each end of the hose. Thus, the first coupling of each joint is identical. Adaptors can be employed if necessary to assist connection between the first couplings and the tap and nozzle. Moreover, the second coupling of each joint is also identical if the hose diameters are identical, or if they are different, the first coupling parts of the second couplings are different, but the second coupling parts remain identical. 
     Where a system of the kind discussed above also employs a connection between two or more hoses, that connection can comprise a pair of second coupling attached together. Thus, in that system, the first couplings connect to the tap and nozzle, and the second couplings attach to each hose end. The system thus comprises only the first and second couplings, with adaptors employed as required. 
     Other aspects of the present invention are embodied in a seal provided for use in a coupling arrangement, in adaptors to facilitate connection of a coupling according to the invention to fluid supply or discharge facilities, particularly existing facilities that are not customised for use with a coupling according to the invention, and in a hose grip which is employed to grip the outside surface of one end of a hose to which a coupling is connected. 
     In one form of the invention, an adaptor is employed with the first coupling for connection of the first coupling to a fluid discharge facility. The use of an adaptor facilitates connection of the first coupling to fluid discharge facilities of various kinds and in particular, to such facilities that include connection arrangements for couplings having a different construction to the first coupling of the present invention, such as prior art couplings. As discussed earlier, a very popular form of connection arrangement particularly used for water nozzles, is a connector which includes a male tubular connector that extends from the nozzle. The male connector includes a coaxial flange and O-ring, which accepts a “click-on” female fitting which is attached to one end of a hose. While this arrangement is popular, for example for connecting water spray nozzles to hoses, the click-on nature of the arrangement introduces significant complexities into the parts of the connection arrangement, which increases both the cost of the arrangement and the likelihood of its failure. Nevertheless, the popularity of the arrangement is such that many households and businesses already have nozzles and other fittings of this kind and therefore it is anticipated that there would be a reluctance to dispose of these fittings in order to adopt the present invention. Accordingly, the adaptor of the invention advantageously permits continued use of existing fittings while adopting the coupling arrangement of the present invention. 
     An adaptor according to one form of the invention includes first and second portions. The first portion is arranged to be secured to the male connector of the fluid discharge facility, while the second portion is arranged to be connected to the first coupling part of the first coupling. The first portion includes an opening through which the male connector can be fed and an edge of the opening is arranged to bear against a bearing surface of a flange of the male connector. That bearing engagement resists removal of the male connector from the opening and thus it resists removal of the adaptor from the male connector. The arrangement is such that with the edge of the opening in bearing engagement with the bearing surface of the flange, and the first coupling part secured to the second portion of the adaptor, the first coupling is secured to the fluid discharge facility. 
     In a preferred arrangement, the opening includes two intersecting portions. A first portion is sized to accept the male connector when the connector is fed into the opening, while the second portion is sized and shaped for engagement with the bearing surface of the connector flange. For a male connector that is cylindrical, each portion can be circular, with the first portion having a diameter that is slightly greater than the maximum diameter of the portion of the male connector that is fed through the opening, and the second portion can be of a reduced diameter and complementary to the diameter of the section of the male connector from which the flange extends. In this arrangement, the circular edge of the second portion can bear radially against the outer surface of the male connector and axially against the bearing surface of the flange. In this arrangement, the axis of the second portion preferably is coaxial with the male connector, while the axis of the first portion is eccentric to the axis of the male connector. Thus the adaptor is shifted eccentrically from the position in which the male connector is fed into the opening, to the position in which the opening bears radially against the outer surface of the connector and axially against the flange. 
     The second portion of the adaptor can be arranged for connection to the first coupling part in any suitable manner. A bayonet or snap connection could be employed, although it is preferred that the connection be a threaded connection. 
     In the above form of adaptor, it is preferred that the adaptor be applied to the male connector first and that the first coupling part thereafter be connected to the adaptor. 
     An alternative form of adaptor also includes first and second portions of which the first portion is arranged to be secured to the male connector of the fluid discharge facility and the second portion is arranged to be connected to the first coupling part of the first coupling. In this alternative form of adaptor, the first portion includes a snap connector, which rides over the flange of the male connector and into bearing engagement with the bearing surface of the flange. The snap connector can include a pair of separate connector parts which engage different sections of the bearing surface, preferably sections which are diametrically opposed. The connector parts either are resiliently flexible or are supported by resiliently flexible elements, so that the parts can resiliently shift to ride over the flange and can then return to bear against the bearing surface. 
     In one arrangement, the second portion includes an annular wall and the snap connector or connector parts are connected to an internal surface of that wall. In this arrangement, a thread can be applied to the outer surface of the wall for threadably connecting the second portion to the first coupling part. 
     In the above alternative form of the adaptor, the snap connector or connectors can include levers for manually releasing the connectors from bearing engagement with the bearing surface, so as to release the adaptor from connection with the fluid discharge facility. Manual release may be by way of finger manipulation of the levers, or a tool, such as a screwdriver may be employed. The levers may be integrally formed with the snap connectors and in one form, the levers extend axially from the snap connectors to a position beyond one axial end of the annular wall of the second portion in the trailing direction of application of the adaptor to the male connector of the fluid discharge facility. In this arrangement, when the first coupling part is connected to the second portion of the adaptor, the first coupling part can enclose the levers against access for manual release. 
     An advantage of the alternative form of adaptor is that the adaptor can be fitted to the first coupling part first and thereafter, the combined adaptor and first coupling part can be fitted to the fluid discharge facility. In contrast, in the first form of the adaptor, the adaptor is fitted to the fluid discharge facility first and then the adaptor and the first coupling part are connected together. 
     The first coupling part preferably includes a connecting section which is connectable to the fluid supply or discharge facility. The connecting section can be arranged for that connection in any suitable manner, although the preferred arrangement includes an annular wall having an internal surface to which a helical thread is applied. The helical thread can be of a form to connect standard threads which are applied to fluid supply facilities such as taps. 
     The passage of the first coupling part can extend from an inboard end of the connection section. This is suitable for coupling parts which are configured for connection to a tap or discharge facility. Thus, the connecting section has an axial extent and the passage commences inboard of an axial end of that section. A seal can be accommodated between one end of the fluid supply facility and the first coupling part, to seal against flow of fluid other than into the passage. For this, a seat can be provided for a seal and in the preferred arrangement, the seat is annular and extends about the opening of the passage, between the passage opening and the connecting section. 
     A first coupling part which is arranged for connection to a flexible fluid line can include a hollow spigot for receipt within an end of the line. The spigot will be in fluid communication with the passage and preferably is coaxial therewith, for example an extension thereof. The spigot preferably tapers slightly to be narrower at its leading end than its trailing end, so that the end of the fluid line into which the spigot is inserted, leading end first, frictionally engages the external surface of the spigot progressively more the further the spigot is inserted. The spigot can be formed integrally with the first coupling part. 
     The passage extends through an interlocking portion of the first coupling part to which the second coupling part can be connected to form a coupling, and to which a second coupling part of another coupling can also be connected. Thus, the interlocking portion is arranged to interlock with the second coupling parts of each of the first and second couplings. The interlocking portion preferably is generally cylindrical and includes projections for interlocking with the respective second coupling parts. The interlocking portion can be in the form of a post or hollow spigot. 
     The interlocking portion can extend from the connecting section of the first coupling part and in a preferred arrangement, a shoulder is defined at the junction of the connecting section and the interlocking portion which extends transverse to and preferably substantially perpendicular to the axis of the passage and which forms an abutment surface for abutment with the second coupling part when the first and second coupling parts are connected together. The interlocking portion can include one or more locking projections spaced from the shoulder and the second coupling part can also include locking lugs that are received between the shoulder and one or more locking projections when the first and second coupling parts are connected together. The locking lugs of the second coupling part are configured to be received between the shoulder and the locking projections and the locking lugs can include abutments to abut one or either side of the locking projections to securely capture them in the appropriate position. The first and second coupling parts can be connected together by rotation, to bring the locking lugs to the position between the abutments and between the shoulder and the locking projections. One of the abutments may be formed at one end of a ramp, so that a locking lug rides over the ramp to be received between the abutments. In this arrangement, either the locking lug or the ramp, or both, are resiliently flexible to facilitate the lug riding over the ramp. Because of the resilient flexing of the locking lug and/or the ramp, this arrangement can be such that the first and second coupling parts are permanently coupled together by permitting flexing to occur in only one direction of rotation. 
     The second coupling part of each coupling includes at least one, but preferably two locking claws, for interlocking with the first coupling part of another coupling. The claws have an axially extending claw section and a radially inwardly extending claw section. The radially extending claw section preferably extends from a distal end of the axially extending section. The second coupling part can include an annular wall from which the locking claws extend and the locking lugs previously described can extend radially inwardly from the wall. The locking lugs and the radially extending claw sections are spaced apart axially. 
     The radially extending claw sections are arranged for locking engagement with further projections extending from the interlocking section of the first coupling part of a coupling. Pairs of projections which are spaced apart axially, can be provided for engagement with a locking lug of one second coupling part and with a radially extending claw section of another second coupling part. 
     The locking engagement between the locking claws and the first coupling part preferably comprises bringing a locking face of each of the radially extending claw section and a projection into engagement, preferably by rotation of the first coupling relative to the second coupling. It should be appreciated that the first and second couplings normally would themselves be fully assembled before being joined together and would be connected respectively to either the fluid supply or discharge facility, or to a hose end. The respective locking faces preferably have an interlocking profile so that the faces nest together in the interlocked position. One face could have a recess for example and the other face could have a protrusion, so that upon receipt of the protrusion within the recess, the radially extending claw section and the projection are locked together. Receipt of the protrusion within the recess preferably causes the first and second couplings to click together, so that a person who is assembling the joint receives a tactile indication that proper interlocking has occurred. The first and second couplings may also include mutually abutting surfaces in the interlocked position, to prevent rotation beyond that position. While the abutting surfaces may be provided in any suitable form, where the second coupling parts include locking claws, the axially extending sections of two locking claws of two separate second coupling parts may abut, preferably through side edges thereof. 
     The seals mounted at one end of a respective passage of the first and second couplings preferably engage sealingly when the first and second coupling are interlocked to form a joint. Preferably the pressure force between the seals increases as the pressure of fluid flowing through the joint increases. This can be achieved by a seal of the kind disclosed in International patent application PCT/AU90/00271, published under WO 91/00469. According to the present invention, a seal of that kind is modified to include a pair of coaxial annular flanges, preferably which extend generally in the direction of fluid flow through the passage. 
     The first flange is received in an annular recess formed in the wall of the passage. The second flange is radially outboard of the first flange and interlocks with an annular end section of the portion of the first coupling part which defines the passage. The interlock can be achieved in any suitable manner. In one form, the annular end section has a reduced diameter section that forms a neck and the neck is engaged by the second flange. To ensure a secure connection, the arrangement can be such as to require the seal to resiliently flex over the end section, whereafter resilient recovery of the seal results in engagement with the neck. 
     A seal according to the present invention includes a flexible annular lip that is engaged by fluid flowing through the passage, which causes the lip to splay outwardly. Movement of this kind occurs in the lip of each of the two facing seals and results in the lips dynamically engaging each other during fluid flow. This results in the pressure between the lips increasing as fluid pressure increases. The annular flanges of the seal extend from positions radially outwardly of the annular lip. 
     The present invention can include a hose grip for gripping the end of a flexible fluid line (hereinafter a hose) to which a second coupling of a joint is to be connected. The hose grip is annular to fit about the hose end and is radially expandable and contractible resiliently along its full axial length. The hose grip of the invention includes a plurality of hinged segments. Each segment is elongate and one end of each segment is hingedly connected to an adjacent end of an adjacent segment on one side thereof, while the opposite end is hingedly connected to the adjacent end of the segment on the opposite side thereof. The hose grip thus can expand and contract either uniformly from one end to the other, or the expansion or contraction can be tapered from one end to the other. 
     Preferably the hose grip is integrally formed and the segments extend generally parallel and in the general direction of fluid flow through the hose end. 
     The arrangement of the hose grip is that it is placed about one end of a hose and thereafter, a clamping nut is slid over the hose grip and is engaged with the connecting section of the first coupling part of the second coupling. The nut frictionally engages the hose grip and applies a load which tends to cause the hose grip to radially contract. By that connection, the hose grip is forced into gripping connection with the hose end to forcibly clamp the hose end about the spigot which extends from the connecting section of the first coupling part of the second coupling as previously described. The connecting section and the nut can be connected in any suitable manner, but preferably the connection is a threaded connection. Preferably as threaded engagement progresses between the nut and the connecting section, the radial force applied to the hose grip increases. For this, the nut can include a tapered internal wall which engages the radially external surface of the trailing end of the hose grip to progressively increase the radial force applied to the hose grip. 
     In a preferred arrangement, the first coupling part of the second coupling can include an annular ring that is concentric with and extends about the spigot of that part, for engagement with the leading end of the hose grip. The annular ring and the leading end of the hose grip can cooperate when assembled together to cause the leading end to radially contract so as to grip the hose end. The annular ring and the hose grip therefore can include faces which slidingly engage, with the faces being inclined, to cause radial contraction of the hose grip as sliding engagement between the faces progresses. The arrangement can be such that the clamping nut can cause radial contraction of one end of the hose grip while cooperation between the hose grip and the annular ring can cause radial contraction of the other end. By this arrangement each end of the hose grip can be radially contracted against the hose end to firmly grip the hose end, by the cooperation at one end of the hose grip with the nut, and at the other end by the annular ring. The annular ring can be integrally formed with the first coupling part. 
     In order to enhance the gripping qualities of the hose grip, the elements of the hose grip can include teeth which bite into the surface of the hose end. Preferably teeth are formed at the hinge connection between adjacent elements of one end of the hose grip. When a hose is fed through the hose grip, the hose preferably is fed first through the end of the hose grip remote at which the teeth are disposed. 
    
    
     
       For a better understanding of the invention and to show how it may be performed, embodiments thereof will now be described, by way of non-limiting example only, with reference to the accompanying drawings. 
         FIG. 1  illustrates a general view of a garden hose arrangement embodying the present invention. 
         FIG. 2  illustrates a water nozzle and in exploded view a coupling for application to the nozzle. 
         FIG. 2   a  illustrates an assembled form of the arrangement of  FIG. 2 . 
         FIGS. 3 and 4  illustrate plan and perspective views of an adaptor according to the invention. 
         FIGS. 5 to 8  illustrate respectively, cross sectional, perspective and side views of a first coupling part according to the invention. 
         FIG. 9  is a cross-sectional view of a seal according to the invention applied to one end of a first coupling part according to the invention. 
         FIGS. 10 and 11  are cross-sectional and perspective views of a second coupling part according to the invention. 
         FIG. 12  is an exploded view of a coupling according to the invention for attachment to a hose end. 
         FIG. 12   a  is a cross-sectional view of a first coupling part of the coupling shown in  FIG. 12 . 
         FIG. 13  is a perspective view of a hose grip according to the invention. 
         FIGS. 14 and 15  are cross-sectional and side views of the assembled form of the exploded assembly shown in  FIG. 12 . 
         FIG. 16  is a cross-sectional view of a pair of hose ends having the same diameters and which are connected by a coupling arrangement according to the invention. 
         FIG. 17  is a perspective view of the coupling arrangement of  FIG. 16  but shown in a pre-connected condition. 
         FIG. 18  is a side view of the arrangement of  FIG. 17  shown in a connected condition. 
         FIG. 19  is a cross-sectional view of a pair of hose ends having different diameters and which are connected by a coupling arrangement according to the invention. 
         FIG. 20  shows an assembly according to the present invention in exploded view, for attachment to a water tap. 
         FIGS. 21 and 22  show side and cross-sectional views of the exploded assembly of  FIG. 20  in an assembled form. 
         FIG. 23  shows a nozzle shown in exploded view, which is customised for use in a coupling arrangement according to the present invention. 
         FIGS. 24 and 25  are cross-sectional and side views of the nozzle of  FIG. 23  shown in an assembled form. 
         FIG. 26  is an exploded view of an alternative form of adaptor according to the present invention. 
         FIG. 27  is a side view of the arrangement shown in  FIG. 26 . 
         FIGS. 28 and 29  are perspective and cross-sectional views of the adaptor shown in  FIG. 26 . 
     
    
    
     The figures to which the following discussion relates, show a complete coupling arrangement for a flexible fluid line. The parts which are discussed can be selected depending on the type of fluid line and it will be appreciated that all of the parts which are discussed are not necessarily required for each application of the coupling arrangement. 
     It will be convenient to commence discussion of the coupling system by reference to parts of the system as they apply to particular components of a flexible fluid line. Because the invention has been principally developed for use with domestic garden hoses, it will be convenient to describe the invention in relation to that application. 
       FIG. 1  is a general view of a garden hose arrangement for which the present invention can be employed.  FIG. 1  shows a fluid supply facility in the form of a tap  10  which is connected to a flexible fluid line or garden hose  11  by a tap joint  12  according to one aspect of the present invention. The hose  11  is connected to a second hose  13  which extends to a fluid distribution device in the form of a pistol grip nozzle  14  and a nozzle joint  15  is employed to couple the hose  13  to the nozzle  14 . A hose joint  16  which has similarities to the joints  12  and  15  is employed to connect the two lengths of hose  11  and  13  together, although where the length of the hose  11  is sufficient, the hose joint  16  will not be necessary. This latter arrangement is illustrated by the hose  11 ′. 
     It will be apparent from the discussion that follows, that the respective joints  12 ,  15  and  16  each comprise two couplings. The joint  15  also includes an adaptor  17 . The joints  12  and  15  comprise a coupling  12 ′ and a coupling  16 ′. The joint  16  comprises two of the couplings  16 ′. Accordingly, each joint comprises at least one common coupling  16 ′. The coupling  12 ′ of the joint  15  is connected by the adaptor  17  to the nozzle  14 . The hoses  11 ,  11 ′ and  13  shown in  FIG. 1  are of the same diameter. However, it is to be appreciated that the invention can accommodate different diameter hoses within a system such as that shown in  FIG. 1 . For example, the hose  11  may be of a different diameter to the hose  13 . In that case, slight modifications to the couplings  16 ′ can be made to accommodate the different sized hose ends. Again, this will be apparent from the discussion that follows. 
     It will be convenient now to disclose the invention in relation to the different joints and couplings shown in  FIG. 1  and with reference to  FIG. 2  there is illustrated the nozzle  14  in broken outline, with the coupling  12 ′ and the adaptor  17  of the joint  15  shown in exploded view.  FIG. 2   a  illustrates the  FIG. 2  arrangement but with coupling  12 ′ shown assembled. 
     The adaptor  17  is connectable to the inlet member  18  of the nozzle  14 . The inlet member  18  is cylindrical and includes an inlet passage (not shown), which is coaxial with the member  18  and which facilitates flow of fluid, such as water, into the nozzle  14  for egress through the opposite end  19 . 
     The construction of the adaptor  17  is such that it can be secured to the inlet member  18  in a manner that will be discussed in relation to  FIGS. 3 and 4 , while the adaptor  17  can also be connected to coupling part  20  by a screw threaded arrangement. Thus the adaptor  17  includes a cylindrical wall  21  which is threaded for engagement with an internal thread of a cylindrical wall  22  of the coupling part  20 . 
     With reference to  FIGS. 3 and 4 , the adaptor  17  includes a castellated flange  23  which is provided for ease of gripping. As best seen in  FIG. 4 , the flange  23  extends inboard to the wall  21  at one end of that wall, and towards the other end of the wall  21 , and internal thereof, an opening  24  is formed in an end plate  25 . The opening  24  is comprised of two intersecting circular portions which are separately defined by part circular edges  26  and  27 . The radius of the part circular edge  26  is greater than that of the part circular edge  27  while the axis of the circular edge  27  is concentric with the axis of the wall  21 . In contrast, the axis of the circular edge  26  is eccentric to the axis of the wall  21  and the circular edge  27 . 
     The opening  24  is arranged to be sufficiently large, that the inlet member  18  of the nozzle  14  can be fed therethrough. Referring to  FIG. 2 , the inlet member  18  includes a O-ring groove  28  defined between a pair of flanges  29 ,  30 . The size of the opening  24  of the adaptor  17  therefore is required to be sufficient to accommodate the passage of the flanges  29  and  30  therethrough as well as an O-ring which is disposed within the groove  28 . In the adaptor  17 , passage of those flanges  29 ,  30  takes places through the larger portion of the opening  24  defined by the part circular edge  26 . However, above the flange  30 , i.e. towards the nozzle end  19 , the inlet member  18  is of reduced diameter. That section of the inlet member  18  is a neck section  31 . The flange  30  therefore defines a cylindrical bearing surface  32  against which the part circular edge  27  can bear against. The edge  27  has a radius complementary to the radius of the outer surface of the neck section  31 . Thus, when the inlet member  18  has been fed through the adaptor  17 , to the extent that the flanges  29  and  30  have passed through the opening  24 , so that the opening  24  is adjacent the neck section  31 , the adaptor  17  can be shifted into coaxial alignment with the longitudinal axis of the inlet member  18  so that the part circular edge  27  radially engages against the side wall of the neck section  31  and bears axially against the bearing surface  32 . The bearing surface  32  is slightly bevelled, and that bevel is repeated is a complementary form through the part circular edge  27  at  27   a , so that the edge  27  and the bearing surface  32  neatly engage against each other. 
     Movement of the adaptor  17  into position on the inlet member  18 , so that the edge  27  bears against the side wall of the neck section  31  and the bearing surface  32 , is the first step in securing a coupling according to the invention to the nozzle  14 . The next step is to bring the coupling part  20  into threaded engagement with the adaptor  17 . A cross-sectional view of the coupling part  20  is shown in  FIG. 5  and that view shows the part  20  as having a neck  35  extending from a shoulder  36  which extends to the internally threaded cylindrical wall  22 . An opening  37  extends coaxially through the coupling part  20  and comprises three distinct portions. The middle portion  38  has a diameter sufficient to snugly accommodate the end of the inlet member  18  which includes the O-ring groove  28 . In practice, an O-ring will be seated within the O-ring groove  28 , and that O-ring will engage against the internal wall  39  of the middle portion  38  to seal against water leakage. Thus, water is fed into the coupling part  20  through the leading opening portion  40  and then into the passage defined within the inlet member  18  which is seated within the middle portion  38 . 
     By fitting the adaptor  17  to the inlet member  18 , and thereafter by threadably connecting the coupling part  20  to the adaptor  17 , the leading end  18   a  ( FIG. 2 ) of the inlet member  18 , is secured within the middle opening portion  38  ( FIG. 5 ) and that securement also secures the adaptor  17  in position with the edge  27  in bearing engagement with both the side wall of the neck section  31  and the bearing surface  32 . This is a particularly simple and effective connecting arrangement and facilitates easy connection of a coupling according to the invention to the popular form of nozzle which is illustrated in  FIG. 2 . The popular part of that nozzle is in fact the shape or configuration of the inlet member  18  and that form of inlet member is applied worldwide to a wide variety of different hose fittings, such as the nozzle  14  illustrated, and other forms of devices, e.g. sprinklers or watering systems. Thus the present invention is operative advantageously to be connected to existing forms of fluid distribution devices. This means that consumers who would like to purchase the coupling system of the present invention, do not also need to purchase new fluid distribution devices which are compatible with the inventive couplings. On the contrary, the inventive couplings can be used with existing fluid distribution devices and that ensures that the coupling of the invention has attractiveness to consumers who already have fluid distribution devices which are in good working order. 
     The coupling part  20  of  FIG. 2  is shown in perspective view in  FIG. 6  and in two side views in  FIGS. 7 and 8 . Those figures show the construction of the neck  35  and the figures show that the neck  35  includes a pair of radially extending projections  41 ,  42  which are aligned axially on diametrically opposite sides of the neck  35 . The axial spacing of the projections  41 ,  42  defines a groove  43  ( FIG. 7 ) between them. The surface  44  ( FIG. 8 ) of the projection  41  defines a pair of inclined surfaces  45  and  46  and a projecting surface  47 . The surfaces  45  to  47  cooperate with a coupling lug which will be described later herein to secure the lug within the groove  43 . 
     The end  48  of the neck  35  is configured for receipt and securement of a flexible seal  50  ( FIG. 2 ). The seal  50  is shown in cross-section in  FIG. 9  attached to the end  48  of the coupling part  20 . The seal  50  includes an annular lip  51  that projects radially inwardly and which has an inclined face  57 . Accordingly, as fluid flows through the neck  35 , the fluid impinges on the face  57  and causes the lip  51  to splay outwardly according to the arrows A. The seal  50  further includes a pair of annular flanges  52  and  53 . The annular flange  53  is disposed within a recess  54  formed in the end  48  of the neck  35 , while the annular flange  52  is seated about the external periphery of the end  48  which defines a neck section  55  having a reduced diameter for complementary receipt of an enlarged end portion  56 . Facing engagement of the enlarged end portion  56  with the neck  55  ensures that the seal  50  is securely attached to the end  48 . 
     Referring back to  FIG. 2 , the coupling part  60  is arranged for connection to the coupling part  20 . The coupling part  60  includes a cylindrical side wall  61  and a pair of diametrically opposed lugs  62  which extend radially inwardly from the side wall  61  adjacent one end of the coupling part  60 . The lugs  62  are configured to be received between the shoulder  36  ( FIG. 7 ) of the coupling part  20 , and the facing projections  42 . The lugs  62  are configured to engage opposite sides  63  ( FIG. 8 ) of the projections  42  so that once the projections  42  are in position relative to the lugs  62 , they are captured in that position against removal therefrom by engagement with the lugs  62 . An internal view of the coupling part  60  is shown in  FIG. 10  and that figure shows one of the lugs  62 , which has a pair of opposed abutment faces  62   a  on either side of a supporting surface  64 . It is intended that the coupling parts  20  and  60  be rotatably connected together and by that rotation, the projections  42  resiliently deform the ramp part  62   b  of each lug  62  downwardly to allow the projection  42  to be positioned between the facing abutment surfaces  62   a  and overlying the supporting surface  64 . When recovery of the resilient deformation takes place, the lugs  42  are captured in that position. Accordingly, the coupling parts  20  and  60  are permanently connected together, while the adaptor  17  is removable from connection therewith. 
       FIG. 11  illustrates the coupling part  60  from the opposite direction to that shown in  FIG. 2  and in that figure, a pair of claws  65  are shown extending from an internal surface of the side wall  61 . The claws  65  are diametrically opposed and extend axially of the coupling part  60 . Each of the claws  65  includes radially inwardly extending projections  66  and those projections have a complementary shape to the shape of the projections  41  shown in  FIG. 8 . Thus, each projection  66  includes a pair of inclined surfaces  67  and a recess  68 . The arrangement of the claws  65  is such that the connected combination of coupling parts  20  and  60  can be sealingly connected to substantially the same combination of parts which is attached to a flexible hose.  FIG. 12  illustrates a hose connection, and reference will now be made to that figure. 
       FIG. 12  illustrates a short portion of hose  70 . The hose  70  would extend away from a fluid distribution device, such as a nozzle  14  and through the nut  71 . 
     The  FIG. 12  arrangement includes a coupling part  60  which is identical to the part which has the same numeral illustrated in  FIG. 2 . Additionally, an identical seal  50  is provided and while the coupling part  72  has significant similarities to the coupling part  20 , it includes a spigot  73  onto which the hose  70  is mounted. Otherwise, like parts have the same reference numeral plus prime. The spigot  73  has a slight increase in taper from the free end thereof so that the hose  70  frictionally engages the spigot towards it inner end. Disposed around the hose  70 , is a hose grip  74  which is radially expandable and contractable by its construction and includes a plurality of teeth  75  that are arranged to bite into the outer surface of the hose  70  when the coupling of the invention is applied to the hose  70 . While not all the teeth  75  are visible in  FIG. 12 , the hose grip  74  is shown in detail in  FIG. 13 , from which it can be seen that the hose grip  74  includes eight teeth, which are formed in a ring at the end  76  of the grip  74 . 
     The grip  74  is radially expandable and contractable, by virtue of its material of construction, which typically will be a resilient plastic material. The grip  74  is formed into hinged segments of which several are identified by the reference numeral  77  and these segments are connected at hinge regions  78 . Again, only a small number of the hinge regions are identified by reference numeral. By the construction of the hose grip  74 , the grip can be fitted to hoses of different wall thickness, by radial expansion of contraction of the grip. 
     Radial contraction of the grip  74  can be caused by engaging either end of the grip  74 , at one end by the nut  71  and at the other end by the coupling part  72  ( FIG. 12 ). For this, the coupling part  72  can include an annular ring  81  (see  FIG. 12   a ) which is concentric with and extends about the spigot  73 . The ring  81  includes a sloping face  82  complementary to the slope of the end  76 ′ ( FIG. 13 ) of the grip  74 . As shown in the cross-sectional assembled view of  FIG. 14 , the end  76 ′ and the sloping face  82  are in engagement and by that engagement, the end  76 ′ is caused to contract radially inwardly into gripping engagement with the hose  70 . Also, the nut  71  engages the end  76  of the grip  74  and causes that end to contract radially inwardly whereby the teeth  75  bite into the hose surface. 
     Returning to  FIG. 12 , the assembly of coupling parts is applied to the hose  70 , firstly by feeding the hose  70  through the nut  71  and thereafter placing the hose grip  74  about the end of the hose  70 . By the resilience of the material of the grip  74 , the grip will radially contract into engagement with the outer surface of the hose  70 , although the grip force will be very low. After the nut  71  and the hose grip  74  have been applied to the hose  70 , the coupling part  72  can be applied to the hose  70  by feeding the spigot  73  into the open end of the hose  70 . Typically the spigot  73  will be a friction fit within the hose  70  by engaging the internal walls of the hose. With the spigot  73  fully received within the hose  70 , the nut  71  can be threadably engaged with the coupling part  72  through the complementary threads  79  and  80  respectively formed on the nut  71  and the coupling part  72 . As the threads  79  and  80  engage, the end  76  of the grip  74  is engaged by the nut  71 , while the opposite end  76 ′ engages the face  82  of the ring  81 . The grip  74  is thus caused to radially contract at each end thereof about the hose  70 , to grip the hose  70 . The teeth  75  of the grip  74  bite into the outer surface of the hose  70 . By this arrangement, each of the nut  71 , the hose grip  74  and the coupling part  72  are securely fixed to the hose  70 . 
     Following on from the above sequence of connections, if the seal  50  is separate from the coupling part  72 , then it is applied to the end  48  of that part in the manner described in relation to  FIGS. 6 and 9 . It is to be noted that the coupling part  60  is intended to be applied to the coupling part  72  in advance of the sequence of connections discussed above. The actual intention is that the parts  60  and  72  are connected together prior to being made available for consumer purchase, and this might be achieved by connecting them together following their manufacture. Once connected together, it is the further intention that the parts  60  and  72  cannot be separated, except destructively while the seal  50  can be replaced. The assembly of  FIG. 12  is illustrated in cross section in  FIG. 14 , while a side view of that assembly is shown in  FIG. 15 . 
     The nozzle coupling assembly shown in  FIG. 2   a  is connectable to the hose coupling assembly of  FIG. 15  by engagement of the respective coupling parts  60  of each assembly. As discussed earlier, the coupling parts  60  applied at the nozzle  14  and the hose  70  are identical and it is the case that the projections  66  of the claws  65  of each coupling parts  60 , are rotatably engageable within the grooves  43  ( FIG. 7 ), of the coupling parts  20  associated with a respective coupling part  60 . The connection requires a simple operation in which the claws  65  of the coupling part  60  associated with the nozzle  14  are introduced into the coupling part  60  associated with the hose  70 . With the claws  65  of the respective coupling parts  60  inserted into one another, relative rotation of the coupling parts  60  bring the projections  66  of the claws  65  into the grooves  43  of the respective coupling parts  20 . The same type of assembly occurs between the coupling parts  60  and  72  ( FIG. 12 ), or coupling parts  60  and  72 ′ ( FIG. 19 ). The projections  66  of the respective claws  65  lock within the grooves  43  by receipt of the projecting surface  47  ( FIG. 8 ), within the recess  68  ( FIG. 11 ), and by seating of the respective inclined surfaces  45 ,  46  and  67 . 
     The joint  16  ( FIG. 1 ) that exists between the hoses  11  and  13  is illustrated in  FIGS. 16 and 18 , in which  FIG. 16  is a cross-sectional view of the joint  16 .  FIG. 17  is a perspective view of the respective hoses  11  and  13  and their coupling assemblies  91 ,  92  prior to connection together, while  FIG. 18  is a side view of the joint  16 . Because many of the parts which will be described in relation to  FIGS. 16 to 18  are identical to the parts of  FIGS. 2 and 12 , the same reference numerals which have been used before to describe those parts will be employed in  FIGS. 16 to 18 . 
     The joint  16  is comprised of two identical mating assemblies  91 ,  92  as follows. Each coupling assembly  91 ,  92  includes a nut  71  which is in threaded engagement with a coupling part  72 . Each assembly further includes a hose grip  74  which, upon threaded connection between the nut  71  and the coupling part  72 , bites into the surfaces of the hose  11  and  13  to secure the nut  71  and coupling part  72  in position relative to the hoses  11  and  13 . In  FIG. 16 , the teeth  75  of the hose grip  74  which is applied to the hose  13  are illustrated as penetrating the surface of the hose  13 . 
     The assemblies  91 ,  92  which make up the joint  16  further include a pair of coupling parts  60  and in relation to the coupling parts  60  and  72   FIG. 16  clearly shows the location of the lugs  62  between the shoulder  36  and the projection  42 .  FIG. 16  further clearly shows the claws  65  and the projections  66  which extend therefrom disposed between the projections  41  and  42  and in locking engagement with the projection  41 . 
     It will be appreciated that the coupling assembly  91  and the coupling assembly  92  are identical. This is permitted because the hoses  11  and  13  are of the same diameter and thus the spigots  73  are also of the same diameter. 
       FIG. 19  shows the  FIG. 16  arrangement, but with the hose  11 ′ of different diameter to the hose  13 . The main difference in  FIG. 19  is in the size of the spigots  73 ′ and  73 . The spigots are of a diameter suitable to be closely received within the respective hoses  11 ′ and  13 . The hose  11 ′ is of a smaller internal diameter than the hose  13  and so the diameter of the spigot  73 ′ within the hose  11 ′ is likewise of a smaller outside diameter compared to the spigot within the hose  13 . Also, the nuts  71 ′ and the hose grips  74 ′ differ in size between the assemblies  91 ′ and  92 . 
       FIG. 19  thus illustrates that the invention can connect hoses of different sizes. The internal diameter of the hose  11 ′ might, for example, be about 12 mm, while the internal diameter of the hose  13 ′ could be about 18 mm. Clearly hoses of other size can be incorporated. 
     Advantageously, the arrangements of the invention minimise the number of different parts required to connect hose sections together. Moreover, it will be appreciated that the coupling part  60  which is illustrated in  FIGS. 16 to 18 , is the same coupling part which is employed for connection to the nozzle  14  ( FIG. 1 ). 
     Reference will now be made to  FIGS. 20 to 22  which show a coupling of the invention being applied to a fluid distribution device in the form of a tap  10  with  FIG. 20  showing the tap  10  and coupling assembly in exploded view and  FIGS. 21 and 22  showing the assembly in an assembled view, in side view and cross-sectional view respectively. 
     With reference to  FIG. 20 , the tap  10  includes a threaded end  101  which is a standard arrangement in relation to domestic outdoor taps. 
     A seal  102  is provided to engage against an end surface  103  of the tap  10  and against an internal surface of the coupling part  20 . The coupling part  20  of  FIG. 20  is identical to the coupling part  20  described earlier in  FIGS. 2 and 5  to  8 , as is the seal  50  and the coupling part  60 . 
     The coupling assembly applied to the tap  10  can be connected to a further coupling assembly connected to a hose, and for example, either of the coupling assemblies  91  and  92  illustrated in  FIG. 17  or coupling assemblies  91 ′ and  92  illustrated in  FIG. 19  could be coupled to the assembly connected to the tap  10 . 
     The coupling arrangement hereinbefore described advantageously comprises a number of identical parts. Each of the coupling assemblies described includes the coupling part  60 , and either the coupling part  20 ,  72  or  72 ′, depending on whether the coupling is to a hose, or to a nozzle or tap. It is to be appreciated that the coupling parts  20 ,  72  and  72 ′ differ as indicated previously. Thus there is significant similarity between each of the couplings which are applied to various parts of the domestic hose system illustrated in  FIG. 1 . Because of this, the system employs more common parts than in the prior art and this provides advantages in relation to manufacturing costs and simplifies the arrangement for consumers who assemble the couplings, while increasing the options for interconnection between different couplings, e.g. for connection between different hose sizes. 
     A significant advantage of the coupling arrangement according to the invention, is that it can provide a significantly reliable seal between parts which are coupled together. Increasingly, water wastage through leakage losses are being targeted as a significant wastage of water and the elimination of leakage between coupled components is extremely desirable. With reference to  FIG. 16 , the respective seals  50  of the joint  16  are shown in face to face engagement in the assembled form of the joint  16 . This provides for initial sealing between the couplings  91  and  92  but a major feature of the seals  50  is that the radially inwardly extending lip  51  (shown more clearly in  FIG. 9 ) is caused to splay outwardly as shown by the arrows A in  FIG. 9  under the action of fluid pressure when fluid flows through the neck  35  of the coupling  20 . The same effect occurs to the seal  50  applied to the coupling part  72 . 
     Returning to  FIG. 16 , with a pair of seals  50  in facing engagement, and with water flowing through the hoses  11  and  13  in either direction, each of the seals  50  are caused to splay in the manner shown in  FIG. 9 . Thus the lips  51  of the pair of seals splay towards each other and as fluid pressure rises, the force with which the respective lips  51  press against each other increases. Thus advantageously, the integrity of the seal formed between the facing seals  50 , increases with fluid pressure. This contrasts with prior art seals between two coupling parts which comprise a pair of facing O-rings. See WO 98/41791 for example. In such prior art arrangements, sealing occurs by forcing the facing O-rings into engagement, but given that fluid pressure tends to force the coupling parts apart, as fluid pressure rises, the sealing pressure between the facing O-rings decreases and thus the seal between the facing O-rings is susceptible to leakage. 
     Thus, the sealing arrangement of the present invention is considered to be secure against leakage and is not prone to leak when subjected to a combination of hot weather conditions and domestic water pressure. Additionally, the arrangement of the claws  65  is such as to increase the strength of the coupling between respective coupling assemblies  91  and  92 , given that the projections  66  of the claws  65  more firmly engage the projections  41  of the coupling parts  20  or  72 , as fluid pressure rises. 
       FIGS. 2 and 20  illustrate the invention as being applied to existing tap and nozzle components. As discussed previously, the ability of the present invention to couple to existing taps and nozzles is advantageous, given that the advantages of the invention, principally the enhanced sealing properties of the invention, can be employed with existing tap and hose componentry, so that a consumer who wishes to take advantage of the enhanced sealing characteristics does not necessarily have to discard the present componentry they have, given that the coupling of the invention is compatible with certain types of existing tap and nozzle componentry. The invention is therefore more likely to be taken up by consumers given that the cost of implementation relates only to the purchase of the couplings themselves. 
     To couple together a system of the kind disclosed in  FIG. 1 , the coupling assemblies on each hose end, is identical. Thus the coupling assembly on each hose end comprises a nut  71 , a hose grip  74 , a coupling part  72 , a seal  50  and a coupling part  60 . Thus, there are five component parts to be assembled to each end of a hose. Although as indicated above, the coupling parts  60  and  72  would normally already be assembled, so that a consumer would not be required to assemble those parts together. At the nozzle, four components are required, comprising an adaptor  17 , a coupling part  20 , a seal  50  and a coupling part  60 . At the tap end, again four components are required, comprising a seal  102 , a coupling part  20 , a seal  50  and a coupling part  60 . Again, the coupling parts  20  and  60  would already be coupled together. 
     In a kit form, to connect a single hose between a tap and a nozzle, the kit would include the following components: 
     Adaptor  17 ×1 
     Coupling part  20 ×2 
     Seal  50 ×4 
     Coupling part  60 ×4 
     Coupling part  72 ×2 
     Hose grip  74 ×2 
     Hose nut  71 ×2 
     Seal  102 ×1 
     The duplication or commonality of parts is evident from the parts list above. 
     Where two hoses are employed then the additional connectors of  FIGS. 16  or  19  are required, depending on whether the hoses are of the same or different diameter. 
     While the above discussion has been made principally in relation to existing tap and hose componentry, the present invention is equally applicable to custom made componentry and a nozzle  110  is illustrated in  FIGS. 23 to 25 . The operation of the liquid dispensing part of the nozzle is of a known kind, such that a shroud  111  is disposed about a central spindle  112  which is integrally formed with a coupling part which is substantially the same as the coupling parts  20  and  72  illustrated earlier. Thus, the coupling part  113  has a neck  114  which is formed identical to the neck  35  of the coupling member  20  and a seal  115  is identical to the seal  50  previously described. Finally, the coupling part  116  is identical to the coupling part  60  previously described. 
     As shown in  FIG. 24 , with the parts shown in  FIG. 23  coupled together, liquid flows through the coupling part  116  and into the coupling part  113 , and thereafter through the spindle  112  and out the shroud  111 . Liquid flows through the spindle  112  through openings in each side thereof, while an O-ring  117  is disposed within the groove  118  to prevent leakage of water. The position of the spindle  112  within the shroud  111  controls the fineness of the water spray, and the position of the shroud  111  is adjusted relative to the spindle  112  by rotation on the thread  119 . 
     Clearly other nozzle devices can be employed with the present invention, but  FIGS. 23 to 25  illustrate that by manufacturing the back end of such devices according to the construction of the couplings discussed earlier, the nozzle or other devices can be made compatible for coupling with other coupling parts of the present invention. 
     An alternative form of adaptor is shown in  FIGS. 26 and 27 . Apart from the adaptor, the components illustrated in  FIGS. 26 and 27  are substantially the same as those illustrated in  FIG. 2  and therefore the same parts have been given the same reference numerals. However, in  FIGS. 26 and 27 , an adaptor  120  is illustrated and further discussion in relation to that feature will be made in relation to  FIG. 28 . 
     The adaptor  120  includes an annular wall  121  and a castellated flange  122  which is provided for ease of gripping. The flange  122  is connected to the wall  121  by four bridging connectors  123  which are disposed equidistantly about the flange  122  at 90° intervals. The bridging connectors  123  separate the annular flange  122  from the wall  121  to create an annular space S, small sections of which are evident in  FIG. 27 . The annular space S forms an opening for the core of a mould which forms thread portions  124 . 
     The wall  121  includes four thread portions  124 . The thread portions  124  are separated by gaps G, which provide space for the core of a mould to form the bridging connectors  123 , although despite the gaps G, the thread portions  124  form a substantially continuous, single revolution helical thread. 
     Radially inwardly of the wall  121 , are a pair of diametrically opposed and substantially identical snap portions  125 . Each snap portion  125  includes engagement portions  126  which taper radially inwardly from the leading end  127  to the trailing end  128 . 
     The snap portions  125  are connected to the internal surface of the wall  121  at hinges  129  (see  FIG. 28 ), and the hinges  129  are resiliently flexible to allow the snap portions  125  to flex inwardly and outwardly as shown by the arrows A in  FIG. 28 . Flexing movement of this kind is required for the snap portions  125  to engage the inlet member  18  of the nozzle  14 . The arrangement is such that the snap portions  125  flex radially outwardly towards the wall  121 , in order to ride over the flanges  29  and  30  of the inlet member  18  and to rest in bearing engagement with the bearing surface  32  of the flange  30 . Movement onto the inlet member  18  is in the direction of the arrow B of  FIG. 28 . Once the snap portions  25  have ridden over the flanges  29  and  30 , the end surfaces  130  of the engagement portions  126  snap into bearing engagement with the bearing surface  32 . 
     Upon application of the adaptor  120  to the inlet member  18 , the coupling part  20  can be threadably connected to the adaptor  120  by threadably engaging the helical thread portions  124 . Thereafter, the seal  50  and the coupling part  60  can be connected as described earlier. 
     Advantageously, the adaptor  120  can be removed from the inlet member  18  by manually gripping the levers  131  to resiliently flex the snap portions  125  to release them from engagement with the bearing surface  32 . Thereafter, the adaptor  120  can be shifted axially off the inlet member  18 . 
     The adaptor  120  is easy to manufacture and it contrasts with the adaptor  17 , by the snap-on nature of its connection with the inlet member  18 . It is considered that this aspect of the adaptor  120  might make it more attractive than the nut  17 , although the nut  17  is considered to provide more secure connection. Accordingly, both forms of nut have advantages. 
     It is to be noted that the arrangements of  FIGS. 2 and 25 , utilizing the separate adaptor  17  and  120 , each require that the coupling part  20  be removed from connection with respective adaptor  17 ,  120 , before the respective adaptor can be removed from the inlet member  18 . In  FIG. 2 , when the coupling part  20  is threadably connected to the adaptor  17 , the adaptor  17  cannot shift out of coaxial alignment with the inlet member  18  and therefore the edge  27  ( FIG. 3 ), cannot be disengaged from the bearing surface  32 . 
     Likewise, with the coupling part  20  threadably connected to the adaptor  120 , the levers  131  are concealed by the wall  22 , so that access to those levers is not available. Accordingly, only after the coupling part  20  is unthreaded from the adaptor  120 , can the levers  131  be accessed for removal of the adaptor  120 . It is to be noted however, that the adaptor  120  will remain fixed to the inlet member  18  because of the snap fit engagement between those two parts, even though the coupling part  20  is removed from connection with the adaptor  120 . In contrast, the adaptor  17  is not positively located on the inlet member  18  unless the coupling part  20  is threadably connected to the adaptor  17 . 
     It should be noted that while the description of drawings has concentrated on a system of the kind shown in  FIG. 1 , the interconnectability of the first and second couplings is such that the following combination of connections can be made:
         first coupling to second coupling;   first coupling to first coupling; and   second coupling to second coupling.       

     Thus, with reference to  FIG. 1 , the couplings  12 ′ can be connected together, as can the couplings  16 ′, as well as the coupling  12 ′ and  16 ′. All of these combinations are within the scope of the present invention. 
     The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.