Abstract:
A vented tailpiece that may be used in existing sink installations is connected to a sink drain and a drainline trap as part of the sink drain line. A vent in the tailpiece releases air upstream of the drainline trap as the air is displaced by liquid flowing through the drain line. A retainer connected to the vent catches liquid escaping through the vent. The retainer may be fitted with an extension if necessary. An overflow valve, which is preferably a float valve, may be attached to the retainer and configured to prevent liquid from spilling out of the retainer if a problem in the drain line causes liquid to back up into the retainer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of co-pending provisional application Nos. 61/204,637 and 61/204,638, both filed Jan. 9, 2009. 
     
    
     FIELD OF INVENTION 
       [0002]    This invention relates to plumbing devices. This invention relates particularly to an apparatus for improving the draining of liquid from a sink. 
       BACKGROUND 
       [0003]    A typical sink installation comprises a sink with a drain connected to a tailpiece, the tailpiece connected to a drainline trap, such as a p-trap or s-trap, and the drainline trap connected to a drain elbow that connects to a drain pipe that transports liquid out of the installation to the sewer or other outlet. The sink drain is covered by a catch, such as a stationary grid cover or a pop-up stopper, to prevent articles from entering and clogging the piping. Unfortunately, an airlock occasionally forms on the underside of the catch, causing the sink to drain slowly by hindering or preventing the displacement of air from the tailpiece and piping, which is needed for liquid to flow out. 
         [0004]    It is common to vent the piping in the installation downstream of the drainline trap, in order to relieve pressure from gas entering the piping from the outlet. A downstream vent is difficult to add to an existing installation because the pipes downstream of the drainline trap are usually inside a wall and cannot be accessed. More importantly, the downstream vent does not prevent the airlock under the sink catch from forming because the drainline trap is always filled with liquid, so that the problematic air is retained between the sink drain and the drainline trap. In order to release the trapped air, a vent between the sink drain and drainline trap is needed. It would be further advantageous if the vent could be added to the drainline after the sink is installed. 
         [0005]    A sink overflow is a channel within the sink that runs from an open port near the top of the sink to a place below the sink drain. The sink overflow is designed to divert water from the sink to the piping once the liquid in the sink reaches a certain level. The sink overflow also helps to relieve the airlock when the channel is empty of liquid. However, the overflow channel is infrequently used, so it is common for mold, mildew, or bacteria to build up in the channel. The buildup can cause a foul odor to emanate from the overflow port, and can also attract pests. Further, the overflow port is an unwanted aesthetic distraction in vanity sinks. 
         [0006]    More and more sinks, including vessel sinks and undermount sinks, are being built without overflows due to their drawbacks. These sinks are typically installed and put into use before the slow-draining problem is recognized. In order to retain the aesthetic value of these sinks, an after-market modification that is not visible and releases the trapped air is needed. 
         [0007]    Therefore, it is an object of this invention to provide a device to relieve trapped air in a sink installation. It is a further object that the device relieve trapped air between the sink drain and the drainline trap. A further object is that the device be easily installed in an existing sink installation. A further object is that the device be hidden from plain view. 
       SUMMARY OF THE INVENTION 
       [0008]    A vented tailpiece is connected to a sink drain and a drainline trap as part of the sink drain line. A vent in the tailpiece releases air upstream of the drainline trap as the air is displaced by liquid flowing through the drain line. A retainer connected to the vent catches liquid escaping through the vent. The retainer may be fitted with an extension if necessary. An overflow valve, which is preferably a float valve, may be attached to the retainer and configured to prevent liquid from spilling out of the retainer if a problem in the drain line causes liquid to back up into the retainer. The vented tailpiece may conform to one or more of the common plumbing sizes so that it may replace unvented tailpieces in existing sink installations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a front perspective view of the preferred vented tailpiece. 
           [0010]      FIG. 2  is a top view of the vented tailpiece of  FIG. 1 . 
           [0011]      FIG. 3  is a cross-sectional view of the preferred vented tailpiece installed between the sink and the p-trap. 
           [0012]      FIG. 4  is a perspective view of an alternative vented tailpiece. 
           [0013]      FIG. 5  is a perspective view of another alternative vented tailpiece. 
           [0014]      FIG. 6  is a cross-sectional view of the tailpiece of  FIG. 5  installed between the sink and the p-trap. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Referring to  FIGS. 1 and 2 , there is illustrated the preferred embodiment of the present invention, a vented tailpiece for installation in a sink drain line. The components of the vented tailpiece may be made in varying dimensions to accommodate placement in any new or existing sink installations, such as those in residential, commercial, industrial, or medical environments. The vented tailpiece comprises a pipe  10  that may be made of any suitable plumbing material, including plastic such as polyvinyl chloride (“PVC”) and acrylonitrile butadiene styrene (“ABS”), and metals such as brass, stainless steel, copper, and zinc alloys. If the vented tailpiece is to be used in a medical environment, the pipe  10  and other components may be made of or coated in an antimicrobial material that is easily sterilized. The pipe  10  has a top end  11  that attaches to a sink drain and a bottom end  12  that attaches to a drainline trap. The pipe  10  may be threaded at the top end  11 , the bottom end  12 , and is preferably threaded at both ends  11 ,  12 , to attach to the sink drain and drainline trap, respectively. Alternatively, the pipe  10  may have a flange (not shown) at one or both ends  11 ,  12  to fit over the sink drain, drainline trap, or both. The pipe  10  is preferably fabricated in dimensions that are common to existing tailpieces, so that the vented tailpiece may replace tailpieces in existing sink installations. Most preferably, the pipe  10  is from six to eight inches long. 
         [0016]    A vent  13  provides access to the interior of the pipe  10  and is positioned on the surface of the pipe  10  between the top end  11  and bottom end  12 . The vent  13  is a hole that allows air in the drain line between the sink drain and the drainline trap to be released from the drain line as it is displaced by liquid draining from the sink. The vent  13  may be any shape but is preferably substantially circular. The vent  13  has a diameter that is sufficient to allow air to escape, and may be as small as a pinhole. The preferred vent  13  diameter is about 0.375 inches. A vent  13  of about 0.75 inches to  1  inch in diameter is shown in the figures for the purpose of clarity. Using the top end  11  as a reference, the vent  13  may be placed any distance from the top end  11  that allows proper air release. This distance may be chosen depending on the existing sink installation in which the vented tailpiece will be used. Specifically, the pipe  10  may need to be longer or shorter to accommodate the existing sink installation. For standard sink installations, the pipe  10  is typically 6-8 inches long. The preferred pipe  10  is about 8 inches long with the vent  13  placed at the midway point of the pipe  10 . Further, the preferred pipe  10  may be modified to fit the sink installation by cutting off part of the pipe  10  from the bottom end  12 , and if the pipe  10  is not long enough for an existing installation it may be fitted with an appropriately-sized standard plumbing pipe extension. The vent  13  functions the same regardless of its radial position on the surface of the pipe  10 . 
         [0017]    As liquid flows past the vent  13 , some liquid may pass through the vent  13 . In order to deflect this liquid back into the drain line, a retainer  14  may be attached to the exterior of the pipe  10  over the vent  13 . The retainer  14  may also be integral with the pipe  10 , and may be made by casting the retainer  14  together with the pipe  10  from the same mold. In the preferred embodiment, the retainer  14  is a single piece of semi-cylindrical metal with a rounded bottom that extends vertically a short distance up the pipe  10  and is permanently attached on the sides and bottom to the surface of the pipe  10 . An open end  15  allows air from the vent  13  to escape. The retainer  14  is attached at the bottom of the vent  13  so that liquid that accumulates in the retainer  14  flows back through the vent  13  and into the drain line. The attachment points are preferably watertight, and the retainer  14  is most preferably welded to the pipe  10 . In alternate embodiments, the retainer  14  may be made of other suitable plumbing materials, and may be permanently or removably attached to the pipe  10 . For example, the retainer  14  and pipe  10  may be PVC, and the retainer  14  may be adhered to the pipe  10  using a waterproof adhesive. Any shape or size of retainer  14  may be used as long as it allows air to escape through the vent  13  and is positioned to deflect liquid back into the drain line. Alternate embodiments may have overflow-preventive elements such as those shown in  FIGS. 4 and 5  and discussed below. 
         [0018]      FIG. 3  illustrates a typical sink installation with the preferred vented tailpiece positioned below the sink  20  drain  21  and attached to the p-trap  23 . When the parts of the sink installation are functioning normally, the vent  13  allows rapid release of air in the drain line, so that liquid in the sink falls through the catch  22 , the drain  21 , into the vented tailpiece and quickly through the p-trap  23 , with very little liquid passing through the vent  13 . What little liquid does pass through is deflected by the retainer  14 . However, if there is a problem in the drain line, such as inadequate venting of gas after the p-trap  23  or a clog in the drain line, the pipe  10  may fill with water and spill continuously through the vent  13  into the retainer  14 . The preferred embodiment of the vented tailpiece is the simplest and most efficient embodiment, because it is an integral unit that does not have moving parts or require special positioning. Therefore, it may be used substantially universally for sinks that would benefit from it. However, it does not provide significant protection against this kind of overflow condition. 
         [0019]      FIGS. 4-6  illustrate alternative embodiments that provide overflow protection. Referring to  FIG. 4 , an extension tube  40  may be permanently or removably attached to the retainer  14  at the open end  15 . The extension tube  40  may be rigid or flexible. Permanent attachment may be accomplished with an adhesive, welding, solder, or similar means, depending on the material used for the retainer  14  and extension tube  40 . Removable attachment may be accomplished with a clip, mating mechanism, or friction fit of the extension tube  40  into the open end  15 . In the illustrated embodiment, the extension tube  40  is preferably made of a flexible, waterproof material, such as a plumbing tube or a clear or opaque rubber tube, and is long enough to extend above the fill line of the sink  20 . The extension tube  40  is held substantially vertically at or near the outer surface of the sink  20 . During a drain line backup, the retainer  14  and extension tube  40  fill with liquid until a hydrostatic equilibrium is reached at the vent  13 , preventing further liquid from passing into the retainer  14 . 
         [0020]    Referring to  FIGS. 5 and 6 , an overflow valve  50  may be attached to the retainer  14  at the open end  15 . In this embodiment, the retainer  14  may comprise a tube having a vertical portion  16  that is substantially parallel to the pipe  10  and an angled portion  17  that connects to the pipe  10 , surrounding the vent  13 . The tube may be the same material as the pipe  10 , or may be a different material suitable for plumbing fixtures. In this embodiment, the retainer  14  is preferably copper. The retainer  14  may be permanently attached, such as by welding, or removably attached. In one example of removable attachment, illustrated in  FIGS. 5 and 6 , a threaded bulkhead  51  is attached to the pipe  10  and surrounds the vent  13 , and the retainer  14  has a mated threaded portion  18  for attaching the retainer  14  to the bulkhead  51 . The angled portion  17  is angled so that liquid that enters the retainer  14  flows back into the drain line through the vent  13 . The angle of the angled portion  17 , with respect to the pipe  10 , is preferably  45  degrees. 
         [0021]    The overflow valve  50  fits over the open end  15  of the retainer  14 . The overflow valve  50  is a housing  52  attached to the retainer  14  and having one or more vent holes  53  that allow air to escape. The housing  52  may be metal, such as brass, stainless steel, or copper, or may be plastic, such as ABS or PVC. The housing  52  may be permanently or removably attached to the retainer  14  by welding, solder, adhesive, mated mechanism, or friction fit, depending on the materials used. Preferably, the housing  52  is metal like the retainer  14  and is welded to the retainer  14 . The housing  52  is preferably cylindrical with a diameter of about 0.75 inches, with four vent holes  53  having a diameter of 0.125 inches, and the retainer  14  is a 0.5 inch diameter pipe. 
         [0022]    A float  54  is disposed in the interior  55  of the housing  52 , and is disposed about a pole  56  passing through or attached to the top of the housing  52 . The pole  56  is a substantially rigid rod, made of metal or rubber, that suspends the float  54  above the open end  15  of the retainer  14 . The float  54  is preferably an annular disc disposed around the pole  56  at the base of the pole  56 . The float  54  is smaller in diameter than the housing  52 , and is made of a buoyant material such as plastic, cork, or rubber. An additional rubber or cork gasket  57  may be attached to the top of the float  54  if the float  54  is made of a material, such as inexpensive Kydex® plastic, that does not completely seal the vent holes  53  on its own. Preferably, the float  54  is permanently attached to the pole  56 , which passes through a hole in the top of the housing  52  that is slightly larger in diameter than the pole  56 . See  FIG. 6 . As liquid rises through the retainer  14  into the housing  52 , the float  54  rises on the surface of the liquid, pushing the pole  56  through the hole in the housing  52 , until the float  54  reaches the top of the housing  52  and covers the vent holes  53 , sealing the overflow valve  50 . Once the drain line backup is repaired, the liquid drains back into the drain line through the vent  13 , dropping the float  54  and allowing air to escape normally. In an alternative embodiment, the pole  56  is permanently attached to the top of the housing  52  and the float  54  has a hole that is slightly larger than the diameter of the pole  56 , allowing it to slide along the pole  56  as the water level rises. 
         [0023]    While there has been illustrated and described what is at present considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the true scope of the invention. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.