Patent Publication Number: US-7712682-B2

Title: Spray gun with rotatable reservoir

Description:
FIELD OF THE INVENTION 
   This invention concerns improvements in liquid spraying apparatus such as a spray gun. More especially, it relates to the connection between the spray gun and a reservoir containing the liquid to be sprayed. The invention has particular application to a releasable connection for detachably mounting the reservoir on the spray gun. 
   BACKGROUND OF THE INVENTION 
   Spray guns are widely used in vehicle body repair shops when re-spraying a vehicle that has been repaired following an accident. In the known spray guns, the liquid is contained in a reservoir attached to the gun from where it is fed to a spray nozzle. On emerging from the spray nozzle, the liquid is atomised and forms a spray with compressed air supplied to the nozzle. The liquid may be gravity fed or suction fed or, more recently, pressure fed by an air bleed line to the reservoir from the compressed air line to the spray gun. 
   Traditionally, the liquid is contained in a rigid pot mounted on the spray gun by engagement of complementary screw threads on the pot and gun. In this way, the pot can be removed for cleaning or replacement. Typically, the pot is secured to the gun empty and has a removable lid by means of which the liquid can be added to the pot while attached to the gun. On completion of spraying, the pot can be removed and the gun and pot cleaned for re-use. 
   Such screw threaded connection requires the reservoir to be rotated several times, typically at least four or five turns, to engage fully the threads and secure the reservoir in a fluid tight manner. This is time consuming and requires considerable care and dexterity on the part of the user. 
   Furthermore, the threads on the gun and pot may be damaged by mis-use, for example if an attempt is made to secure a pot having a non-matching thread. Also, on completion of spraying, careful cleaning is required to remove all traces of liquid from the threads to prevent the threads becoming blocked, for example with dried paint, and to prevent cross-contamination with the liquid next sprayed. 
   Damaged or blocked threads may render the gun unusable requiring the purchase of a new gun. This adds to costs and is inconvenient if time is lost because a spare gun is not to hand to continue spraying. Moreover, cleaning of the threads usually requires solvents that are also used to clean the gun and pot. The use of solvents is undesirable from health and safety considerations and causes problems for disposal of the solvent after use. 
   These problems can be reduced by employing a bayonet type connection to secure releasably the reservoir to the spray gun by engagement of bayonet type formations on the reservoir and spray gun with a push-twist action requiring less than one complete turn of the reservoir to connect/disconnect the reservoir. Examples of bayonet type formations that can be used to provide a releasable quick-fit connection of this type are disclosed in International Patent Applications No. WO 98/32539 and WO 01/12337 the disclosures of which are incorporated herein. 
   The mounted position of the reservoir is fixed by the use of screw threads or bayonet formations to secure the reservoir to the spray gun and adjustments to the mounted position cannot be made with the reservoir attached to the spray gun. Typically, the reservoir has an outlet located at one end on the central longitudinal axis of the reservoir and the spray gun has an inlet at the top (gravity feed) or bottom (suction feed) that is located on the central longitudinal axis of the gun. 
   A system has been developed that allows the reservoir to be re-filled while attached to the spray gun by means of an inlet located at the end of the reservoir adjacent to the outlet as described in International Patent Application No. WO 02/085533 the disclosure of which is also incorporated herein. With this system, access to the inlet when the reservoir is connected to the spray gun may be improved by arranging the outlet from the reservoir to be offset from the central longitudinal axis of the reservoir. 
   Such offset arrangement of the outlet can, however, result in the reservoir extending to one side of the spray gun when the outlet is connected to the inlet on the spray gun by engagement of screw threads or bayonet formations to secure releasably the reservoir. 
   Also, in a gravity feed arrangement, the reservoir is connected to an inlet on the top of the spray gun and the offset arrangement of the outlet may position the outlet above the level of liquid in the reservoir when the spray gun is used at different angles, especially when the liquid level reduces. This can have an adverse effect on flow of paint to the outlet especially when a small volume of paint remains in the reservoir. As a result, the spray gun may have to be maneuvered and held in a position that is uncomfortable for the user in order to dispense the final volume of paint. 
   SUMMARY OF THE INVENTION 
   The present invention has been made from a consideration of the foregoing problems and disadvantages of the existing methods for securing a reservoir to a spray gun. 
   More particularly, embodiments of the present invention provide an improved releasable connection between the gun and reservoir that enables the reservoir to be attached to and detached from the gun in a simple manner. 
   Furthermore, at least some embodiments of the present invention provide an improved connection between a spray gun and reservoir such that the mounted position of the reservoir can be adjusted relative to the spray gun while the reservoir is attached to the spray gun. 
   Moreover, at least some embodiments of the present invention provide such improved connection between the gun and reservoir that does not require a high degree of dexterity on the part of the user to adjust the mounted position of the reservoir and/or to connect/disconnect the reservoir. 
   Additionally, at least some embodiments of the present invention provide such improved connection between the gun and reservoir such that the reservoir can be connected to and disconnected from the spray gun by axial movement only relative to the spray gun. 
   Thus, according to one aspect of the present invention, there is provided liquid spraying apparatus comprising a spray gun having an inlet, a reservoir for a liquid to be sprayed, connector means connecting an outlet from the reservoir to the inlet of the spray gun to permit the liquid to be withdrawn from the reservoir in use, the connector means being releasable for detaching the outlet from the inlet, and permitting rotation of the outlet relative to the inlet while the reservoir is attached to the spray gun without compromising the integrity of the connection between the reservoir and the spray gun 
   By this invention, the integrity of the connection between the reservoir and spray gun is maintained while permitting rotation of the outlet of the reservoir relative to the inlet of the spray gun. In this way, the mounted position of the reservoir can be adjusted while attached to the spray gun to provide optimum balance and handling of spray gun for all spray positions and conditions. Furthermore, adjusting the mounted position of the reservoir while attached to the spray gun may allow the outlet from the reservoir to be positioned at the lowest point to ensure that all the liquid can be withdrawn from the reservoir in use. 
   As used herein, the term “liquid” refers to all forms of flowable materials that can be applied to a surface using a spray gun (whether or not they are intended to colour the surface) including (without limitation) paints, primers, base coats, lacquers, varnishes and similar paint-like materials as well as other materials such as adhesives, sealers, fillers, putties, powder coatings, blasting powders, abrasive slurries, mould release agents and foundry dressings which may be applied in atomised or non-atomised form depending on the properties and/or the intended application of the material and the term “liquid” is to be construed accordingly. 
   Preferably, the connector means permits rotation of the reservoir outlet through at least 90°, preferably at least 180° and more preferably at least 360° relative to the spray gun inlet with the outlet of the reservoir in communication with the inlet of the spray gun. 
   Advantageously, the connector means comprises at least one resilient clip on one of the reservoir and spray gun engageable with an abutment on the other of the reservoir and spray gun to resist axial separation of the reservoir and spray gun while permitting rotation of the reservoir outlet relative to the spray gun inlet. 
   In a preferred arrangement, the reservoir outlet and spray gun inlet are connectable by push fit and the resilient clip comprises a spring leg arranged to extend substantially parallel to the direction of movement of the reservoir outlet towards/away from the spray gun inlet and the abutment comprises a ledge transverse to said direction of movement. In this way, the spring leg engages behind the ledge when the reservoir outlet is connected to the spray gun inlet and can rotate relative to the ledge while resisting axial separation of the reservoir outlet from the spray gun inlet. 
   Preferably, one of the spring leg and ledge has a cam face arranged to deflect the spring leg when the reservoir outlet is connected to the spray gun inlet to allow a distal end of the spring leg to pass the ledge and latch behind the ledge to secure releasably the reservoir to the spray gun. In this way, the spring leg and ledge are engageable automatically to secure the reservoir to the spray gun. 
   Advantageously, the distal end of the spring leg has an undercut retainer face arranged to latch behind the ledge and the spring leg is manually deflectable to position the retainer face clear of the ledge to release the reservoir and allow the reservoir outlet to be disconnected from the spray gun inlet. In this way, the reservoir outlet is connected to and disconnected from the spray gun inlet by axial movement only between the reservoir and spray gun. 
   Preferably, the cam face and retainer face are provided by a projection that extends outwards from the distal end of the spring leg towards the reservoir outlet and has a transverse width greater than the spring leg. In this way, the contact surface area of the retainer face with the ledge is increased. As a result, the retention of the reservoir by engagement of the retainer face with the ledge may be enhanced without any adverse affect on the ability of the spring leg to deflect resiliently to secure/release the reservoir. Furthermore, the increased width of the projection may allow the projection to bridge any circumferential discontinuities in the ledge such that engagement with the ledge to secure the reservoir is maintained. 
   Advantageously, the projection is of generally triangular shape and the distal end of the spring leg is connected to an apex of the triangular projection. In this way, the projection extends in the direction of rotation of the reservoir to either side of the spring leg and forces transmitted to the spring leg through engagement of the projection with the ledge are balanced. 
   The spring leg may be provided on the spray gun (or an inlet adaptor secured to the spray gun) and the ledge on the reservoir. More preferably, however, the spring leg is provided on the reservoir and the ledge on the spray gun (or an inlet adaptor secured to the spray gun). 
   In a preferred arrangement, the reservoir outlet is provided by a tubular spout extending from a lid at one end of the reservoir, and the spray gun inlet is provided by a socket in the body of the spray gun (or an inlet adaptor secured to the spray gun). Preferably, the socket is arranged to receive the spout in a fluid-tight manner. For example, the spout may be provided with one or more annular seal formations providing a fluid-tight seal with the opposed wall of the socket. 
   Preferably, the spring leg is spaced from and extends substantially parallel to the spout and the ledge is provided by an external flange on the body of the spray gun (or an inlet adaptor secured to the spray gun). In this way, the secured position of the reservoir can be adjusted by rotational movement of the spout relative to the socket without compromising the fluid connection between the spout and the socket. 
   The spout may be aligned with a central longitudinal axis of the reservoir. Alternatively, the spout may be offset relative to the central longitudinal axis of the reservoir. The reservoir may be provided with an inlet in the lid separate from the spout through which liquid can be added to the reservoir when the reservoir is connected to the spray gun. The inlet may be provided with a removable closure cap for opening/closing the inlet. 
   The reservoir may be re-usable. For example, the lid may be attached to a rigid container that is removed from the spray gun and cleaned on completion of spraying. The amount of cleaning required may be reduced by containing the liquid in a disposable lid/liner assembly within an outer container of the type disclosed in International Patent Application No. WO 98/32539. Alternatively, a disposable reservoir may be employed that can be removed and thrown away after use. 
   According to another aspect of the present invention, there is provided liquid spraying apparatus comprising a spray gun having an inlet, a reservoir for a liquid to be sprayed, the reservoir having an outlet connectable to the inlet of the spray gun to permit the liquid to be withdrawn from the reservoir in use, the inlet and outlet defining a connection axis when engaged, and retainer means operable in response to connection of the reservoir outlet and spray gun inlet to permit rotation of the reservoir outlet relative to the spray gun inlet about the connection axis and to resist separation of the reservoir outlet and spray gun inlet in a direction parallel to the connection axis in all angular adjusted positions of the reservoir relative to the spray gun. 
   Preferably, the retainer means is self-latching in response to connection of the reservoir outlet and spray gun inlet to secure the reservoir to the spray gun and is manually releasable when it is desired to disconnect the reservoir outlet from the spray gun inlet. 
   The retainer means may permit unrestricted rotation of the reservoir relative to the spray gun through 360° about the connection axis. In this way, the reservoir may be rotated to any angular adjusted position after connection of the outlet to the spray gun inlet and the retainer means is operable to resist removal of the reservoir in all angular adjusted positions. 
   According to yet another aspect of the invention there is provided a reservoir for use with a spray gun, the reservoir having an outlet for connection to an inlet on the spray gun and a resilient retainer clip for self-latching engagement with the spray gun to secure the reservoir to the spray gun, the arrangement being such that the reservoir outlet can be rotated relative to the spray gun inlet while the reservoir is connected to the spray gun and the retainer clip is operable to secure the reservoir in all rotationally adjusted positions of the outlet. 
   Preferably, the outlet is provided at an end of the reservoir and the reservoir has an inlet separate from the outlet at the same end such that liquid can be added to the reservoir while the outlet is connected to the spray gun. 
   Advantageously, the outlet is offset relative to a central longitudinal axis of the reservoir and the reservoir can be rotated while connected to the spray gun to align the central longitudinal axis with a central longitudinal axis of the reservoir. Alternatively or additionally, the reservoir can be rotated to position the outlet at the lowest point of the reservoir to allow substantially all of the liquid to be withdrawn from the reservoir in use. The reservoir may also be rotatable to facilitate access to an inlet where provided for adding liquid to the reservoir while connected to the spray gun. 
   According to yet another aspect of the present invention, there is provided a connector system for securing a reservoir to a spray gun, the system comprising a resilient retainer on one of the reservoir and spray gun, and an abutment on the other of the reservoir and spray gun, the retainer being engageable with the abutment when an outlet of the reservoir is connected to an inlet of the spray gun to prevent separation of the reservoir and spray gun while permitting rotation of the reservoir relative to the spray gun. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of liquid spraying apparatus comprising a gravity feed spray gun and reservoir according to the prior art; 
       FIG. 2  is a perspective view of the reservoir shown in  FIG. 1  separate from the spray gun; 
       FIG. 3  is a longitudinal section through the reservoir shown in  FIG. 2 ; 
       FIG. 4  is a perspective view showing a modified reservoir according to the prior art; 
       FIG. 5  is a perspective view showing the reservoir of  FIG. 4  attached to a spray gun, the gun being shown inverted and the reservoir inlet open; 
       FIG. 6  is a perspective view showing another modified reservoir according to the prior art; 
       FIG. 7  is a perspective view showing the reservoir of  FIG. 6  attached to a spray gun, the spray gun being shown inverted to illustrate access to the reservoir inlet; 
       FIG. 8  is an exploded perspective view of an alternative bayonet connection system for a reservoir according to the prior art; 
       FIG. 9  is an end view of the adaptor shown in  FIG. 8 ; 
       FIG. 10  is a side view of a fully rotatable connection system for a reservoir according to a first embodiment of the present invention; 
       FIG. 11  is a plan view of the fully rotatable connection system shown in  FIG. 10 ; 
       FIG. 12  is a plan view, to an enlarged scale, of the connection system shown in  FIG. 11 ; 
       FIG. 13  is a plan view of a fully rotatable connection system for a reservoir employing the prior art adaptor shown in  FIGS. 8 and 9  according to a second embodiment of the present invention; 
       FIG. 14  is a plan view, to an enlarged scale, of the connection system shown in  FIG. 13 ; 
       FIG. 15  is a perspective view, to an enlarged scale, from one side of the connection system shown in  13 ; 
       FIG. 16  is a perspective view showing an alternative arrangement of the spring leg shown in  FIGS. 10 to 15 ; 
       FIG. 17  is a perspective view of a spray gun and reservoir employing the connection system of  FIGS. 13 to 15 , the spray gun being shown for spraying a vertical panel with the reservoir in a first position; 
       FIG. 18  is a perspective view of the spray gun and reservoir of  FIG. 17  with the reservoir in a second position; 
       FIG. 19  is a perspective view of the spray gun and reservoir of  FIG. 18 , the spray gun being shown for spraying a horizontal panel with the reservoir in the second position; 
       FIG. 20  is a perspective view of the spray gun and reservoir of  FIG. 19  with the reservoir in the first position; 
       FIG. 21  is a perspective view showing the spray gun and reservoir of  FIG. 17  in an inverted position; and 
       FIG. 22  is a perspective view showing the spray gun and reservoir of  FIG. 21  with the reservoir rotated to allow access to the inlet. 
   

   DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
   Referring first to  FIGS. 1 to 3  of the accompanying drawings, there is shown a liquid spraying apparatus of the type disclosed in International Patent Application No. WO 98/32539 comprising a gravity feed spray gun  1  and a reservoir  2  releasably secured to the spray gun  1 . 
   The gun  1  comprises a body  3 , a handle  4  which extends downwards from the rear end of the body, and a spray nozzle  5  at the front end of the body. The gun  1  is manually-operated by a trigger  6  which is pivotally-mounted on the sides of the gun. 
   In use, the gun  1  is connected via a connector  7  at the lower end of the handle  3  to a source of compressed air (not shown) and the reservoir  2  contains paint or other liquid to be sprayed. Compressed air is delivered through the gun  1  to the nozzle when the user pulls on the trigger  6  and paint is delivered under gravity from the reservoir  2  through the gun  1  to the nozzle  5 . As a result, the paint is atomised on leaving the nozzle  5  to form a spray with the compressed air emerging from the nozzle  5 . 
   As best shown in  FIGS. 2 and 3  of the drawings, the reservoir  2  includes an outer container  8 , a disposable liner  9 , a disposable lid  10  and a collar  11 . The liner  9  corresponds in shape to (and is a close fit in) the interior of the container  8  and has a narrow rim  12  at the open end which sits on the top edge of the container  8 . 
   The lid  10  is of conical shape and has a dependent skirt  13  inset from the peripheral edge. The skirt  13  is a push-fit in the open end of the liner  9  to locate the peripheral edge of the lid  10  over the rim  12  of the liner  9 . The lid/liner assembly is secured in place by the annular collar  11  that screws onto the container  8  on top of the lid  10 . 
   The lid  10  has a central aperture  14  that leads to a spout  15  providing a fluid outlet and a mesh filter  16  is arranged to remove particulate material from paint delivered through the tube  15  to the spray gun  1  in use. In this embodiment, the filter  16  is a push fit in the skirt  13  but it will be understood this is not essential and the filter  16  may be a push-fit in the tube  15  or may be an integral part of the lid  10 . For some applications, the filter  16  may not be required and can be omitted. 
   The distal end of the spout  15  is provided with a pair of opposed outwardly directed bayonet lugs  18 . The spray gun  1  has a tapped hole (not shown) in the top of the body  3  in which a threaded end of an inlet adaptor  19  is received. The other end of the adaptor  19  is provided with a socket (not shown) in which the spout  15  is received and secured by engagement of the bayonet lugs  18  with bayonet grooves (not shown) in the internal wall of the socket. 
   The bayonet formations on the spout  15  and socket of the inlet adaptor  19  are engageable with a push twist action that secure the reservoir  2  in a fixed position relative to the gun body  3 . In this embodiment, the spout  15  is aligned on the central longitudinal axis of the reservoir  2  and the socket in the adaptor  19  is aligned with the central longitudinal axis of the spray gun  1 . As a result, when the reservoir  2  is connected to the spray gun  1 , the central longitudinal axes of the reservoir  2  and spray gun  1  lie substantially in the same vertical plane when the reservoir is upright and the reservoir  2  is not offset to one side of the spray gun  1 . In this way, balance and handling of the spray gun  1  are optimised. 
   In use, the liner  9  collapses in an axial direction towards the lid  10  as paint is withdrawn from the reservoir  2 . A vent hole  8 A in the base of the outer container  8  allows air to enter as the liner  9  collapses. On completion of spraying, the reservoir  2  can be detached from the spray gun  1 , the collar  11  released and the lid/liner assembly removed from the outer container  8  in one piece. The outer container  8  and collar  11  are left clean and ready for re-use with a fresh liner  9  and lid  10 . In this way, extensive cleaning of the reservoir  2  may be avoided. 
   The lid/liner assembly may be used to store any paint remaining for a short period of time and re-assembled with the container  8  and collar  11  for attachment to the spray gun  1  to use the remaining paint. Alternatively, the lid/liner assembly can be thrown away when all the paint has been used or is no longer required. 
   Referring now to  FIGS. 4 and 5 , there is shown a modification to the reservoir of  FIGS. 1 to 3  by means of which the reservoir can be filled while attached to the spray gun as described in International Patent Application No. WO 02/085533. For convenience, like reference numerals in the series  100  are used to indicate parts corresponding to  FIGS. 1 to 3 . 
   As shown the lid  110  of the reservoir  102  has an inlet  120  separate from the spout  115 . The inlet  120  is provided with a detachable closure cap  121  that can be removed when the spray gun  101  is inverted as shown in  FIG. 5  to allow paint to be added to the reservoir  102  while attached to the spray gun  101 . 
   The reservoir  102  is again secured by engagement of bayonet lugs  118  with bayonet grooves (not shown) in a socket (not shown) of an inlet adaptor  119  secured to the spray gun  101 . The mounted position of the reservoir  102  is fixed by the engaged position of the bayonet lugs  118  and grooves which in turn depend on the screw threaded engagement of the inlet adaptor  119  with the spray gun  101 . 
   As a result, when the reservoir  102  is attached to the spray gun  101 , it can happen that the spray gun body  103  restricts access to the inlet  120 . If this happens, the mounted position of the reservoir  102  cannot be adjusted to improve access to the inlet  120  without compromising the connection between the reservoir  102  and the spray gun  101  and the integrity of the fluid seal between the spout  115  and the inlet adaptor  119 . 
   Thus, the reservoir  102  can only be rotated in a direction to release the bayonet lugs  118  from the bayonet grooves of the socket in the inlet adaptor  119  such that the reservoir  102  would become detached from the inverted spray gun  101 . 
   Referring now to  FIGS. 6 and 7 , there is shown a modification to the reservoir of  FIGS. 4 and 5  whereby access to the inlet may be improved when the reservoir is attached to the spray gun. For convenience, like reference numerals in the series  200  are used to indicate parts corresponding to  FIGS. 4 and 5 . 
   As shown the lid  210  of the reservoir  202  has an outlet spout  215  and a separate inlet  220  with a detachable closure cap  221 . In this embodiment, the lid  210  is of frusto-conical shape and the outlet spout  215  is offset from and extends at an angle to the central longitudinal axis of the reservoir  202 . 
   In this way, the inlet  220  may be made larger and, when the reservoir  202  is connected to the spray gun  201 , access to the inlet  220  is facilitated making the addition of paint to the reservoir  202  while attached to the spray gun  201  easier. 
   The reservoir  202  is again secured by engagement of bayonet lugs  218  with bayonet grooves (not shown) in a socket (not shown) of an inlet adaptor  219  secured to the spray gun  201 . The mounted position of the reservoir  202  is fixed by the engaged position of the bayonet lugs  218  and grooves which in turn depend on the screw threaded engagement of the inlet adaptor  219  with the spray gun  201 . 
   As a result, when the reservoir  202  is attached to the spray gun  201 , it can happen that the offset arrangement of the outlet spout  215  causes the alignment of the central longitudinal axes of the reservoir  202  and spray gun  201  to be lost. As a result, the reservoir  202  may be offset and extend to one side of the spray gun body  203  which can have an adverse effect on balance and handling of the spray gun  201 . 
   Furthermore, depending on the way in which the reservoir  202  is presented to the inlet adaptor  219 , the reservoir  202  can be secured in one of two positions according to user preference such that the outlet spout  215  is above or below the inlet  220 . Where the spout  215  is above the inlet  220 , a dead space is created in the reservoir  202  where paint may become trapped making it difficult to maneuver the spray gun  201  during use to remove all of the paint from the reservoir  202 . 
   If this happens, the mounted position of the reservoir  202  cannot be adjusted to re-position the spout  215  without compromising the connection between the reservoir  202  and the spray gun  201  and the integrity of the fluid seal between the spout  215  and the inlet adaptor  219 . As a result, paint may be left in the reservoir  202  which is wasteful and causes problems for safe disposal of the reservoir  202 . 
   Referring now to  FIGS. 8 and 9 , there is shown an alternative bayonet type connection of the type disclosed in International Patent Application No. WO 01/12237 that can be used to secure the reservoir to the spray gun. For convenience like reference numerals in the series  300  are used to indicate parts corresponding to the previous embodiments. 
   As shown, the bayonet connection is provided by engagement of a pair of hook members  322  on the lid  310  of the reservoir  302  with an external flange  323  on the inlet adaptor  319 . 
   The flange  323  is formed with a pair of circumferentially spaced recessed portions  324 . Each recessed portion  324  comprises a major recess  324   a  and a minor recess  324   b  separated by a lobe  324   c.    
   The major recesses  324   a  are sized to allow the hook members  322  on the lid  310  to pass freely when the spout  315  is inserted in the socket of the adaptor  319 . Thereafter the reservoir  302  is rotated to position the hook members  322  in the minor recesses  324   b  and locate the hook members  322  over the flange  323  to secure the reservoir  302 . 
   The mounted position of the reservoir  302  is fixed by location of the hook members  322  in the minor recesses  324   b  and the spout  315  of the reservoir  302  cannot be freely rotated in the socket of the adaptor  319 . 
   Referring now to  FIGS. 10 ,  11  and  12 , there is shown a first embodiment of a releasable connector system for securing a reservoir to a spray gun according to the present invention. For convenience, like reference numerals in the series  400  are used to indicate parts corresponding to  FIGS. 1 to 9 . 
   As shown, the lid  410  of the reservoir  402  is provided with an outlet spout  415  and a separate inlet  420  having a detachable closure cap  421 . The lid  410  is of frusto-conical shape with the spout  415  being offset from and inclined relative to the central longitudinal axis of the reservoir  402  allowing the size of the inlet  420  to be increased. 
   The spout  415  is cylindrical and is a push fit in a mating cylindrical socket (not shown) in the inlet adaptor  419 . The spout  415  may be provided with sealing means such as O-rings (not shown) or ribs (not shown) to provide a fluid tight seal with the opposed wall of the socket while permitting rotation of the spout  415  in the socket as described below. 
   The connector system for securing the lid  410  to the spray gun (not shown) comprises an integral spring leg  425  on the lid  410  and an annular flange  423  on the adaptor  419 . 
   As shown in  FIG. 10 , the spring leg  425  extends substantially parallel to and is radially spaced from the spout  415 . The distal end of the spring leg  425  has a lateral projection  426  with a chamfer face  427  leading to an undercut retainer face  428  to one side of the leg  425 . In this embodiment, the spring leg  425  is positioned between the spout  415  and the inlet  420  but it will be understood that this is not essential and the spring leg  425  may be located at any position around the spout  415 . 
   In use, the chamfer face  427  is co-operable with the flange  423  of the adaptor  419  as the spout  415  is inserted in the socket of the adaptor  419  to deflect the distal end of the spring leg  425  outwards until the projection  426  passes the flange  423 . The spring leg  425  then returns to its original position due to its inherent resilience causing the projection  426  to locate behind the flange  423 . As a result, axial separation of the spout  415  from the socket in the adaptor  419  is prevented by engagement of the retainer face  428  of the projection  426  with the opposed face  429  of the flange  423 . 
   As shown in  FIG. 12 , the projection  426  is of generally triangular shape being wider at the end arranged to overlie the opposed face  429  of the flange  423 . In this way, the surface area of the retainer face  428  engageable with the opposed face  429  of the flange  423  is enhanced and effectively resists release of the reservoir  402  if an axial force is applied to withdraw the spout  415  from the socket of the adaptor  419 . 
   The distal end of the spring leg  425  is also provided with a manually operable actuator in the form of an annular release button  430  that extends outwards from the other side of the spring leg  425  away from the narrow end of projection  426 . 
   In use, the spring leg  425  can be deflected to move the projection  426  clear of the flange  423  by finger pressure applied to the actuator button  430 . The spout  415  can then be withdrawn axially from the socket in the adaptor  419  to disconnect the reservoir  402  from the spray gun (not shown). 
   As shown in  FIG. 10 , the flange  423  is provided at one end of the adaptor  419  and the other end has an external screw thread  432  for securing the adaptor  419  to the spray gun (not shown). Between the flange  423  and the screw thread  432 , the adaptor  419  has a cylindrical portion  433  and a hexagonal portion  434 . The adaptor  419  may be rotated by engaging the hexagonal portion  434  with a spanner or the like (not shown) to connect or disconnect the adaptor  419 . In a modification (not shown) the inlet adaptor  419  may be permanently secured to or formed integrally with the spray gun body (not shown). 
   As shown in  FIG. 12 , the projection  426  terminates at an outer edge  435  that extends substantially tangential to the cylindrical portion  433  of the adaptor  419 . In this way, the projection  426  rotates around the cylindrical portion  433  and maintains engagement with the flange  423  if the spout  415  is rotated in the socket of the adaptor  419 . As a result, the position of the reservoir  402  relative to the spray gun (not shown) can be adjusted without releasing the reservoir  402 . 
   In this way, the reservoir  402  can be rotated through 360° relative to the spray gun (not shown) to position the centre of gravity of the reservoir  402  to optimise balance and handling while spraying. For example, the central longitudinal axes of the reservoir  402  and spray gun (not shown) may be arranged in substantially the same vertical plane when the spray gun is used in an upright position. Alternatively, the central longitudinal axis of the reservoir  402  may be offset to one side of the central longitudinal axis of the spray gun if the spray gun is used at an angle or if space is restricted. 
   Furthermore, during spraying the reservoir  402  can be rotated to position the spout  415  at the lowest point to prevent a dead space occurring in the reservoir  402  where paint may be trapped. Moreover, when it is desired to add paint to the reservoir through the inlet  420 , the reservoir  402  can be rotated to a position in which access to the inlet  420  is facilitated. 
   As will be appreciated, the lid  410  may be provided with more than one spring leg  425  arranged to engage the flange  423  on the adaptor  419  to secure releasably the reservoir  402  to the spray gun (not shown) while permitting rotation of the reservoir  402  relative to the spray gun. Furthermore, it will be appreciated that flange  423  does not require any recesses to engage/disengage the spring leg  425 . The flange  423  can therefore be of a uniform, annular shape that is simpler to manufacture than the flange shown in  FIGS. 8 and 9 . 
   Referring now to  FIGS. 13 to 15 , there is shown a modification to the connector system of  FIGS. 10 to 12  employing the prior art adaptor shown in  FIGS. 8 and 9 . For convenience, like reference numerals in the series  500  are used to corresponding parts. 
   As shown, the triangular shape of the projection  526  at the distal end of the spring leg  525  is such that the projection  526  can bridge the major recess  524   a  to engage the opposed face  529  of the flange  523  on either side of the recess  524   a . In this way, engagement of the projection  526  with the flange  523  is maintained if the reservoir  502  is rotated to a position in which the spring leg  525  is opposite the major recess  524   a . Similarly, engagement is maintained if the reservoir  502  is rotated to align the spring leg  525  with the minor recess  524   b.    
   In this way, the reservoir  502  can be connected to a spray gun (not shown) provided with the adaptor  519  of a prior art bayonet connection system and the capability of full rotation of the reservoir  502  through 360° while attached to the spray gun is maintained. As a result, the same adaptor  519  can be used to provide a bayonet connection as shown in  FIGS. 8 and 9  or a rotatable latch connection as shown in  FIGS. 13 to 15 . 
   With reference now to  FIG. 16 , an alternative arrangement of the spring leg of the connector systems of  FIGS. 10 to 15  is shown. For convenience, like reference numerals in the series  600  are used to indicate corresponding parts. 
   As shown, the spring leg  625  is now positioned on the opposite side of the outlet spout  615  adjacent to the outer edge of the lid  610 . In this way, access to the annular release button  630  at the distal end of the spring leg  625  may be enhanced when the reservoir (not shown) is connected to a spray gun (not shown). As a result, manual release of the spring leg  625  to allow the reservoir to be detached from the spray gun may be facilitated. It will be understood that the spring leg  625  may be located at any angular position with respect to the spout  615  and that more than one spring leg  625  may be provided at circumferentially spaced positions around the spout  615 . 
   As will now be appreciated, the spring leg and flange provide a self-latching connector system for automatically securing a reservoir to a spray gun and permitting rotation of the reservoir relative to the spray gun while connected to the spray gun. More specifically, the self-latching engagement of the spring leg with the flange resists axial separation of the reservoir from the spray gun while allowing unrestricted rotation of the reservoir through 360° and is manually releasable when the reservoir is to be disconnected from the spray gun. 
   In this way, the reservoir can be rotated relative to the spray gun without compromising the integrity of the connection between the reservoir and the spray gun. In particular, the fluid tight seal between the reservoir and the spray gun is maintained to prevent liquid leaking out between the spout and socket as the reservoir is rotated. In the above-described embodiments, the seal between the spout and socket also acts to maintain the reservoir in any angularly adjusted position so that unrestricted rotation of the reservoir is prevented as the attitude of the spray gun is adjusted for different spray positions. 
   Various benefits and advantages of the rotatable connector system above-described will now be described with reference to  FIGS. 17 to 22  which show a spray gun and reservoir employing the rotatable connector system of  FIGS. 13 to 15 . It will be understood that the benefits and advantages also apply to the rotatable connector system of  FIGS. 10 to 12  and to the modification of  FIG. 16 . For convenience, like reference numerals in the series  700  are used to indicate parts corresponding to parts described and illustrated previously. 
   Referring first to  FIG. 17 , the spray gun  701  is shown in an upright position with the spray nozzle  705  arranged to provide a horizontal spray such as when spraying a vertical surface. The reservoir  702  is shown secured to the inlet adaptor  719  by the spring leg  725  and the inlet to the reservoir  702  positioned above the body  703  of the spray gun  701 . 
   In this orientation of the spray gun  701  and reservoir  702 , the inlet to the reservoir  702  is below the outlet creating a dead space within the reservoir  702 . As a result, when spraying, the liquid level in the reservoir  702  may fall below the level of the outlet connection to the spray gun  701 . If this occurs, the reservoir  702  can be rotated through 180 degrees to the position shown in  FIG. 18  so that the outlet  714  is below the inlet  720  to allow the user to continue spraying without interruption. In this way, substantially all the liquid can be withdrawn from the reservoir  702  without changing the attitude of the spray gun  701  when spraying a vertical surface. 
   Referring now to  FIG. 19 , the spray gun  701  is shown turned through 90 degrees from the position shown in  FIG. 18  to arrange the nozzle  705  to provide a vertical spray such as when spraying a horizontal surface. 
   In this orientation of the spray gun  701  and reservoir  702 , the outlet connection to the spray gun  701  is again above the lowest point of the reservoir creating a dead space within the reservoir  702  in which the liquid level can fall below the outlet as shown. If this happens, the reservoir  702  can be rotated through 180 degrees to the position shown in  FIG. 20  so that the outlet connection is at bottom of the reservoir  702  to allow the user to continue spraying without interruption and without changing the attitude of the spray gun  701 . 
   Referring now to  FIG. 21 , the spray gun  701  is shown inverted from the position shown in  FIG. 17 . The reservoir  702  provides a stable base over which the spray gun  701  can be balanced without disconnecting the spray gun  701  from the reservoir  702 . As a result, the user can put the assembly of the spray gun  701  and reservoir  702  down temporarily without risk of spillage or leakage of liquid from the reservoir  702 . 
   In this orientation of the spray gun  701  and reservoir  702 , access to the closure cap  721  is restricted. If it is desired to add liquid to the reservoir  702 , this can be done while the spray gun  701  is inverted without disconnecting the reservoir  702  by rotating the reservoir  702  to the position shown in  FIG. 22 . In this position, the reservoir  702  is inclined at a larger angle to the vertical relative to the spray gun  701  and access to the closure cap  721  is facilitated. As a result, the closure cap  721  can be removed and liquid added to the reservoir  702  while attached to the spray gun  701 . 
   As will now be appreciated, rotation of the reservoir relative to the spray gun allows the user to optimise the ergonomics and balance of the assembly when the reservoir is attached to the spray gun. In addition, the occurrence of dead spaces or lost volume within the reservoir can be minimised to enable substantially all the liquid to be withdrawn from the reservoir in any attitude of the spray gun. Furthermore, where provided, access to the inlet opening may be facilitated to allow easier addition of liquid to the reservoir while attached to the spray gun. 
   It will be appreciated that the exemplary embodiments described herein are intended to illustrate the diverse range and application of the invention and that features of the embodiments may be employed separately or in combination with any other features of the same or different embodiments. 
   Moreover, while the exemplary embodiments described and illustrated are believed to represent the best means currently known to the applicant, it will be understood that the invention is not limited thereto and that various modifications and improvements can be made within the spirit and scope of the invention as generally described herein. 
   Thus, the invention has been described with reference to a reservoir in which the outlet spout is offset from the central longitudinal axis of the reservoir. It will be appreciated however, that the invention is not limited to such arrangement and that the connector system can be employed with reservoirs in which the outlet spout is aligned with the central longitudinal axis of the reservoir. 
   It will also be appreciated that a separate inlet for adding liquid to the reservoir while attached to the spray gun may be provided at any position in the reservoir. Alternatively, the separate inlet may be omitted. 
   Other modifications and changes will be apparent to those skilled in the art. For example, the arrangement of the spring leg on the lid of the reservoir and the co-operating flange on the inlet adaptor of the spray gun may be reversed so that the spring leg is on the inlet adaptor and the co-operating flange is on the lid. Alternatively, the inlet adaptor may be omitted and the spray gun body provided with one of the spring leg and co-operating flange with the other of the spring leg and co-operating flange being on the lid of the reservoir. 
   The part provided with the flange may have a locking member that can be moved between an operative position in which it prevents release of the spring leg and an inoperative position in which it permits release of the spring leg. For example, a locking ring slidably and rotatably mounted on the part provided with the flange. 
   The lateral projection of the spring leg for engaging the flange may be of any suitable shape but is preferably designed to provide a large contact surface area with the flange. In this way, the spring leg effectively resists axial separation of the reservoir and can maintain engagement if the flange has a non-circular profile due to local discontinuities or irregularities. 
   The outlet spout and associated connector formation may be formed on a lid of the reservoir as described or any other suitable part of the reservoir. 
   The reservoir may be of any construction for containing paint to be delivered to the spray gun. For example, the reservoir may comprise a disposable lid/liner assembly that can be thrown away after use as described in International Patent Application No. WO 98/32539. The lid and liner may be separate components for assembly with a re-usable outer container and collar. Alternatively, the lid and liner may be permanently secured together in which case the outer container and collar may not be required. In another arrangement, the reservoir may comprise a re-usable paint pot that is cleaned on completion of spraying. 
   The reservoir may be pre-filled with the paint to be sprayed. Alternatively, the reservoir may be supplied empty and filled by the end user. Pre-filling may be advantageous for spraying paints of standard colours that do not require special matching of the colour, for example primers, base coats etc. 
   The spray gun may be of the gravity feed type as described in the exemplary embodiments. Alternatively, the spray gun may be of the suction feed type or pressure feed type. The pressure feed type may employ a bleed line from the compressed air supply to the gun to assist delivery of the paint from the reservoir to the spray gun. The invention may also apply to other types and constructions of spray guns for spraying liquids as defined herein.