You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION 
       [0001]    This invention relates to a drain fitting. In particular, the invention relates to a drain fitting for use in floor and shower wastes for both commercial and domestic applications and will be described in this context. However, it should be appreciated that the drain fitting may be used for other applications. 
       BACKGROUND OF THE INVENTION 
       [0002]    Waste water drain pipes have been around for thousands of years and still play an important part in most buildings throughout the world. A common problem with waste water drain pipes is that odours can be emitted from them that offend most people&#39;s olfactory senses. This is mainly due to debris, such as food, hair and/or detergent, passing into the waste water drain pipe, decomposing and creating putrid water. 
         [0003]    A reasonably effective way in which to overcome offensive smells that are emitted from waste water drain pipes is to install an S-bend. An S-bend provides a water seal in the pipe to prevent odours from passing from upwardly from below the water seal. This water that forms the water seal is changed every time water passes through the pipe. 
         [0004]    A difficulty with the S-bend is it is generally located a long way from the floor waste. Therefore, debris can become stuck within the drain pipe between the floor waste and S-bend to create an unpleasant odour. Further, a substantial proportion of the debris that creates odour floats in water. Therefore, it becomes trapped in the water in the S-bend. The trapped debris, as described above, creates putrid water and an offensive smell. 
         [0005]    International Patent Application No. WO 99/27199 shows a drain fitting that is used in floor and shower wastes to assist in preventing odours from passing out of the floor and shower wastes. The drain fitting includes a conduit, a cage and a base cap. The cage is attached to the conduit and the base cap. The conduit extends through the cage such that an outlet of the conduit is located within the base cap. Apertures extend through the cage. 
         [0006]    In order to install the drain fitting, a grate is attached to the drain fitting and the grate is placed within a waste body so that the drain fitting is located within a drain pipe. In use, water passed through the conduit to fill the base cap with water. Any excess water passes out of the base cap, through the apertures and down the drain pipe. When water stops passing through the floor waste into the conduit, water located within the base cap covers the outlet to provide a water seal to prevent odours from passing through the drain pipe and out of the grate. The water located within the base cap is replaced every time the water passes through conduit. 
         [0007]    Unfortunately, the drain fitting disclosed in WO 99/27199 has an inherent problem. Debris that passes through the floor and shower wastes often become lodged in the base cap and/or the apertures. This debris, as it decomposes, creates putrid water in base cap which can be smelt through the floor or shower waste. 
       OBJECT OF THE INVENTION 
       [0008]    It is an object of the invention to overcome and/or alleviate one or more of the above disadvantages and/or provide the consumer with a useful or commercial choice. 
       SUMMARY OF THE INVENTION 
       [0009]    In one form, the invention resides in a drain fitting comprising:
       a cage having a plurality of apertures extending through the cage;   a conduit having an inlet and an outlet, the conduit extending at least partially through the cage; and   a base cap attached to the cage, the outlet located within the base cap;   wherein the conduit includes an internal surface that extends from the inlet to the outlet, the internal surface increasing the velocity of the water substantially the length of the internal surface as the water  50  passes from the inlet to the outlet.       
 
         [0014]    The cage is normally a tube. The tube is typically cylindrical in shape. The surface area of the apertures is normally larger than the surface area of the remainder of the cage. 
         [0015]    The conduit may be a funnel. The funnel may have an upper portion and a lower portion. 
         [0016]    The internal surface may be in the form of a number of internal walls. Typically the internal walls are inclined. Preferably, the internal walls are inclined at an angle of at least 30 degrees. More preferably, the internal walls are inclined at an angle of at least 45 degrees. Still more preferably, the internal walls are inclined at an angle of at least 60 degrees. 
         [0017]    An internal wall of the upper portion is preferably between 50 degrees and 70 degrees. More preferably, the internal wall of the upper portion is between 55 degrees and 65 degrees. Most preferably, internal wall of the upper portion upper portion is between 57.5 degrees and 62.5 degrees. 
         [0018]    An internal wall of the lower portion is preferably at least 75 degrees. More preferably, the internal wall of the lower portion is between at least 80 degrees. Most preferably, internal wall of the upper portion upper portion is at least 82.5 degrees. 
         [0019]    The base cap usually includes a floor. Preferably the floor is arcuate. The base cap may also include a stem which extends upwardly from the floor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0020]    An embodiment of the invention will be described with reference to the accompanying drawings in which: 
           [0021]      FIG. 1  shows a perspective view of a drain fitting according to a first embodiment of the invention; 
           [0022]      FIG. 2  shows a further perspective view of the drain fitting of  FIG. 1 ; 
           [0023]      FIG. 3  shows a top view of the drain fitting of  FIG. 1 ; 
           [0024]      FIG. 4  shows a front view of the drain fitting of  FIG. 1 ; 
           [0025]      FIG. 5  shows a side sectional view of the drain fitting of  FIG. 1 ; 
           [0026]      FIG. 6  shows an exploded side sectional view of the drain fitting of  FIG. 1 ; 
           [0027]      FIG. 7  shows a section view of the drain fitting of  FIG. 1  when attached to a shower waste; 
           [0028]      FIG. 8  shows a sectional view of the drain fitting of  FIG. 1  when water is passing through a shower waste; 
           [0029]      FIG. 9  shows a sectional view of the drain fitting of  FIG. 1  with an alternative base cap; and 
           [0030]      FIG. 10  shows a sectional view of the drain fitting of  FIG. 4  with an attached expansion member. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0031]      FIGS. 1 to 7  show a drain fitting  10  for use in a shower waste  11  to assist in preventing odours from passing out of the shower waste  11 . A typical shower waste  11  includes a grate  12  and a waste body  13  as shown in  FIG. 7 . The grate  12  normally fits within the waste body  13  using a bayonet type attachment. 
         [0032]    The drain fitting  10  includes a conduit  20 , a base cap  30  and a cage  40 . The conduit  20 , base cap  30  and cage  40  are all made from plastic. However, it should be appreciated that the conduit  20 , base cap  30  and cage  40  may be made from other materials such a metal. 
         [0033]    The conduit  20  is used to increase the velocity of water  50  that flows through the conduit  20 . The conduit  20  is in the form of funnel that has an upper portion  21  and a lower portion  22 . The upper portion  21  of the conduit  20  has an internal wall  23  that is inclined at an angle of approximately 60 degrees. The lower portion  24  of the conduit  20  has an internal wall  24  that is inclined at approximately 85 degrees. An inlet  25  to the conduit  20  is located adjacent an end of the upper portion  21  and an outlet  26  of the conduit  20  is located adjacent an end of the lower portion  24 . 
         [0034]    A grate attachment lip  27  is located adjacent the inlet on an external wall  28  of the upper portion  21 . A lip thread  29  extends around the grate attachment lip  27 . The grate  12  is fitted to the grate attachment lip  27  via an internal thread located on the grate  12 . 
         [0035]    The base cap  30  is located adjacent the outlet  26  of the conduit  20  such that the outlet  26  is located within the base cap  30 . The base cap  30  is made from a foot  31  and a depending skirt  32 . The foot  31  is arcuate in shape. The depending skirt  32  extends upwardly from the foot  31 . A stem  33  extends up from the foot  31 . 
         [0036]    The base cap  30  is integrally formed with the cage  40 . However, it should be appreciated that the base cap  30  and cage  40  may be attached to each other by different methods. For example, the base cap  30  may be attached to the cage  40  via an internal thread formed in the depending skirt. 
         [0037]    The cage  40  is used to hold the base cap  30  so that the outlet  26  is located within the base cap  30 . The cage  40  is a cylindrical tube  41  having a series of apertures  42  and  43  that extend through the tube  41 . There are a first set of four apertures  42  extending through the tube  41  adjacent one end of the tube and a second set of four apertures  43  extending through the tube  41  adjacent the opposite end of the tube  41 . The first set of apertures  42  are offset with respect to the second set of apertures  43 . The apertures  42  and  43  are sized and arranged so that water can easily pass from one side of the tube  41  through to the other side of the tube  41 . It should be appreciated that the number, size and orientation of the apertures  42  and  43  may be varied. An internal thread  44  is located adjacent the end of the tube  41  for attachment of the base cap  30 . 
         [0038]      FIG. 7  shows a cross-sectional view of the drain fitting  10  attached to the shower waste  11  at rest. As is shown, water  50  is located within the base cap  30 . The water  50  in the base cap  30  covers the outlet  26  and provides a water seal. This assists in preventing odours from passing up a drain pipe  15  and out of the shower waste  11 . 
         [0039]      FIG. 8  shows a cross-sectional view of the drain fitting  10  when water is flowing through the drain fitting  10 . In use, water  50  travels along a shower floor before it passes through the grate  12  of the shower waste  11 . Hence, the water is travelling relatively slowly in a horizontal direction. When the water passes through the grate  12  and through the inlet  25  of the conduit  21 , it contacts the internal wall  23  of the upper portion  21  of the conduit  20 . 
         [0040]    As the internal wall  23  of the upper portion  21  is angled at  60  degrees, the velocity of the water  50  increases as it passes through the upper portion  21  under the force of gravity. The water  50  then passes onto the internal wall  24  of the lower portion  22  of the conduit  20 . As the internal wall  22  of the lower portion  22  is angled at 85 degrees, the velocity of the water  50  increases further under the force of gravity. 
         [0041]    The water  50  then passes out of outlet  26  travelling at a relatively high velocity. The water  50  then crashes into the base cap  30 . The stem  33  directs the water  50  from the outlet along the arcuate floor  31  of the base cap  30  upwardly adjacent the depending skirt  32  and into the tube  41 . The water  50  then passes through the first and second set of apertures  42  and  43  of the tube  41 . Any water  50  that is forced adjacent the external wall  28  of the upper portion  21  and is deflected out of the apertures  42  and  43 . 
         [0042]    The drain fitting  10  is less likely to have debris becoming lodged in the base cap  30  and/or the cage  40  due to the velocity of the water  50  being increased as it passes through the conduit  20 . If debris does become lodged in the base cap  30  and/or cage  40 , the next time the drain fitting is used and water passes through the drain fitting  10 , the increased velocity of the water  50  generally flushes any old debris from the base cap  30  and/or cage  40 . Hence, the likelihood of any decomposing debris causing an odour problem is unlikely. 
         [0043]      FIG. 9  shows an alternative base cap  30  that is large in size than the base cap  30  shown in  FIGS. 1 to 3 . This base cap  30  may be used when debris is wanting to be captured. After the debris is captured in the large base cap  30 , the drain fitting  10  can be removed and cleaned. This is especially helpful if any hazardous materials, such as heavy metals or medical waste, are used on a floor that should not be washed down in the sewage system. 
         [0044]      FIG. 10  shows an extension member  60  that is used when a larger grate  12  is required. The extension member  60  has an extension body  61 , an extension grate attachment lip  62  and a conduit attachment lip  63 . The extension grate attachment lip  61  has an external thread  64  and is used to attach a grate  12  to the extension member  60 . The conduit attachment lip  63  has an internal thread  65  and is used to attach the extension member  60  to the conduit  20 . Once the extension member  60  is attached to a grate  12  and to the conduit  20 , the drain fitting  10  operates as described above. 
         [0045]    It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit or scope of the invention.

Summary:
A drain fitting comprising a cage having a plurality of apertures extending through the cage; a conduit having an inlet and an outlet, the conduit extending at least partially through the cage; and a base cap attached to the cage, the outlet located within the base cap wherein the conduit includes an internal surface that extends from the inlet to the outlet, the internal surface increasing the velocity of the water substantially the length of the internal surface as the water passes from the inlet to the outlet.