Abstract:
In one aspect, the invention is directed to a plumbing drain system comprising a drain line and a valve. The drain line has a drain inlet. The valve is situated in the drain line, spaced from the drain inlet. The valve is positionable between an open position wherein liquid flow is permitted through the drain line and a closed position wherein liquid flow is substantially prevented through the drain line, so that a portion of the drain line upstream of the valve can hold a drain line cleaning solution for a selected period of time.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a cleaning assistance apparatus, such as an after-valve that can be installed downstream from any type of plumbing trap, permitting drains of plumbing fixtures, such as kitchen sinks and the like, to be cleaned when using a cleaning solution.  
         BACKGROUND OF THE INVENTION  
         [0002]    It is well known to provide drains for a variety of plumbing fixtures, with some sort of trap, to ensure that, at all times, the line is closed by water retained in the line. This is achieved by simply providing a trap whose highest point is lower than the immediately upstream and downstream portions of the drain line or conduit. Then, even after discharged water has passed through the drain line, the trap will be full of water, to close off the line, as shown in FIG. 1. This prevents offensive odors that originate from build-up downstream from the trap from venting out through a drain inlet in the sinks. Such traps are commonly identified as P-traps or U-traps, due to their characteristic shape. Odors, however, often emanate from sinks and other plumbing fixtures regardless of the presence of a trap.  
           [0003]    An ongoing battle that is being waged, in kitchens, bathrooms and other areas where plumbing fixtures are present, is the seemingly hopeless task of controlling the bad odors emanating from the drains of plumbing fixtures, such as, for example, kitchen sinks. All kinds of strong smelling cleaning agents are used to try to overcome this problem, but at best, only very temporary relief of any odors can be achieved, largely due to the strong smell of the cleaning agent itself, which masks the bad odors.  
           [0004]    The cleaning agent can do little more than clean the plumbing trap itself underneath the sink, and even that is not done very efficiently. Consequently, there is a constant need to pour cleaning agents down the drains. Indeed, the smells emanating from some sinks can get so dreadful that it becomes necessary to pour cleaning agents into the drains regularly.  
           [0005]    A representational drawing of a typical double sink system that is used in most kitchens is shown in FIG. 1. The two sinks each have drain inlets that are connected to the center outlet of a drain line, which combines the two drain inlets into a single pipe that is connected to a standard plumbing trap before being joined into the vented drainage system of the house. As explained above, the purpose of the plumbing trap is to provide a water barrier between the vented drainage system of the house and the sinks. This is in order to prevent any bad odors in the vented drainage system downstream from the trap from escaping out through the drain inlets of the sinks.  
           [0006]    As shown in FIG. 2, after a prolonged period of use, there can be a substantial build-up of matter that is deposited on the inside walls of the drain line upstream from the trap, within the trap, and also downstream from the trap. These deposits of matter can consist of all manner of foul and disease-ridden substances, which can grow and fester.  
           [0007]    The plumbing trap is long established, and it works very well indeed for its intended purpose of blocking the passage of bad odors that originate downstream from the trap, preventing those bad odors from reaching the drain line upstream from the trap and escaping out through the drain inlets of the sinks. Unfortunately, the plumbing trap does nothing whatever to prevent any of the bad odors that originate from build-up inside the pipes upstream from the trap, from escaping out through the drain inlets of the sinks. It is these bad odors that are the cause of so much distress and frustration when dealing with drain lines, such as, for example, sink drain lines.  
           [0008]    Furthermore, the build-up of matter on the inside walls of the drain lines can become substantial enough over time, to partially or entirely restrict the flow of drain liquids through the drain line. However, this build-up occurs regardless of the presence of the trap.  
           [0009]    As shown in FIG. 3, when a cleaning solution (such as caustic soda or sodium hypochlorite) is poured into the drain line of the sink, it all immediately collects only in the trap itself, and any excess merely passes through the vented drainage system of the house and into the sewers. Virtually none of the cleaning solution stays in the pipes upstream from and downstream from the trap, and therefore the residence time required for the cleaning agent to work on the build-up is not provided. Thus a significant cleaning of these portions of drain line is not achieved. Consequently, as shown in FIG. 4, after the cleaning solution has been flushed away, only the trap itself has been cleaned, and all of the matter deposits remain on the inside walls of the drain line upstream from and downstream from the trap, even after repeated cleaning. Thus, the offensive odors from the matter upstream from the trap will continue to emanate out from the drain inlets of the sinks. Furthermore, the build-up of matter can continue to grow and restrict the flow of drain liquids through the drain lines.  
           [0010]    The build-up of foul and disease-ridden matter inside of the drain line upstream from the plumbing traps of plumbing fixtures, such as kitchen sinks and the like, can not only result in unpleasant odors emanating from the drain lines of those kitchen sinks, but it could also be a health hazard, and can add to indoor pollution. In those situations where offensive odors from the drain lines of kitchen sinks have become unbearable, and strong smelling cleaning agents are constantly being poured into those drains, this excessive use of strong smelling cleaning agents may itself be contributing to the indoor pollution as well.  
           [0011]    There is a need for an apparatus to facilitate the cleaning of the drain line of plumbing fixtures, such as kitchen sinks, bathroom sinks, urinals, showers, bathtubs, liquid storage tanks.  
         SUMMARY OF THE INVENTION  
         [0012]    In a first aspect, the invention is directed to a plumbing drain system comprising a drain line, a trap and a valve. The drain line has a drain inlet. The trap is downstream from the drain inlet and is for holding a sufficient volume of liquid to close off the drain line. The valve is situated in the drain line, downstream from the drain inlet. The valve is positionable between a normally open position wherein liquid flow is permitted through the drain line and a closed position wherein liquid flow through the drain line is substantially prevented, so that a portion of the drain line upstream of the valve and including the trap can retain a drain line cleaning solution for a selected period of time.  
           [0013]    In a second aspect, the invention is directed to a plumbing drain line cleaning apparatus for use with a drain line cleaning solution to clean a drain line. The apparatus includes a valve. The valve is mountable in the drain line, downstream from the inlet to the drain line. The valve is positionable between an open position wherein liquid flow is permitted through the drain line and a closed position wherein liquid flow is substantially prevented through the drain line, so that a portion of the drain line upstream of the valve can hold the drain line cleaning solution for a selected period of time.  
           [0014]    In a third aspect, the invention is directed to a kit of parts for use with a cleaning solution to clean a drain line, the drain line having a drain inlet. The kit of parts comprises a section of drain line and a valve integrally mounted in the section of drain line. The valve includes a plunger housing and a plunger, the plunger housing is connected to and extends from the section of drain line. The plunger has a plunger body that is movably mounted in the plunger housing and sealingly engaged with the plunger housing to prevent liquid flow therethrough. The plunger body is movable in the plunger housing between an extended position wherein the plunger body extends into the section of drain line to substantially block liquid flow therethrough, and a retracted position wherein the plunger is substantially removed from the section of drain line to permit liquid flow therethrough. The plunger further includes a handle for moving the plunger body between the retracted and the extended positions.  
           [0015]    In a fourth aspect, the invention is directed to a method for cleaning a drain line system, the drain line system including a drain line having a drain inlet, the drain line system including a trap situated in the drain line, the method comprising:  
           [0016]    closing the drain line off to flow therethrough, at a point of closure that is downstream from the trap;  
           [0017]    filling the drain line with cleaning solution, so that substantially all of the drain line upstream of the point of closure is filled with cleaning solution; and  
           [0018]    opening the drain line to flow therethrough after a selected period of time corresponding to the time required for the cleaning solution to clean the drain line.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0019]    For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made to the accompanying drawings, in which:  
         [0020]    [0020]FIG. 1 shows a side sectional view of a typical double sink system of the prior art, that is used in some kitchens;  
         [0021]    [0021]FIG. 2 shows a side sectional view of the double sink system shown in FIG. 1, after a prolonged period of use, and illustrates the build-up of matter that occurs inside of the drain line and the trap, as well as the resultant offensive odors;  
         [0022]    [0022]FIG. 3 shows a side sectional view of the double sink system shown in FIG. 1, with cleaning solution inside the trap;  
         [0023]    [0023]FIG. 4 shows a side sectional view of the double sink system shown in FIG. 1, after the cleaning solution has been flushed away;  
         [0024]    [0024]FIGS. 5 a  and  5   b  show side sectional views of a plumbing trap after-valve in accordance with a first embodiment of the present invention, having a centrally pivoted flap in open and closed positions;  
         [0025]    [0025]FIGS. 6 a  and  6   b  show side sectional views of a plumbing trap after-valve in accordance with a second embodiment of the present invention, having an end pivoted flap in open and closed positions;  
         [0026]    [0026]FIGS. 7 a  and  7   b  show side sectional views of a plumbing trap after-valve in accordance with a third embodiment of the present invention, having a vertical sliding plate that can be moved up or down in order to open or close the valve;  
         [0027]    [0027]FIGS. 8 a  and  8   b  show side sectional views of a plumbing trap after-valve in accordance with a fourth embodiment of the present invention, having a rotatable plug section with a pass-through conduit therethrough, whereby the plug can be turned from an open position wherein the pass-through conduit is aligned with the drain line, thereby permitting flow therethrough, to a closed position wherein the pass-through conduit is not aligned with the drain line, preventing flow therethrough;  
         [0028]    [0028]FIGS. 9 a  and  9   b  show side sectional views of a plumbing trap after-valve in accordance with a fifth embodiment of the present invention, having a vertically sliding plunger that can be moved up and down in order to open and close the valve;  
         [0029]    [0029]FIG. 10 shows a side sectional view of a double sink system having the plumbing trap after-valve shown in FIGS. 9 a  and  9   b  installed behind the trap;  
         [0030]    [0030]FIG. 11 shows a side sectional view of the proposed double sink system after a prolonged period of use, with a build-up of matter that occurs inside of the drain line and the trap, as well as the resultant offensive odors;  
         [0031]    [0031]FIGS. 12, 13 and  14  illustrate a procedure in accordance with a sixth embodiment of the present invention, to clean the drain line of the double sink system shown in FIG. 11;  
         [0032]    [0032]FIG. 15 shows a perspective view of a plumbing trap after-valve in accordance with a seventh embodiment of the present invention, for use with plumbing connections that are soldered or glued or the like;  
         [0033]    [0033]FIG. 15 b  shows a perspective view of the plumbing trap after-valve shown in FIG. 15, with an optional knob;  
         [0034]    [0034]FIG. 16 shows an exploded perspective view of the plumbing trap after-valve of FIG. 15;  
         [0035]    [0035]FIG. 17 shows a perspective view of a plumbing trap after-valve in accordance with an eighth embodiment of the present invention, for use with compression type plumbing connections;  
         [0036]    [0036]FIG. 17 b  shows a perspective view of the plumbing trap after-valve shown in FIG. 17, with an optional knob;  
         [0037]    [0037]FIG. 18 shows an exploded perspective view of the plumbing trap after-valve shown in FIG. 17;  
         [0038]    [0038]FIG. 19 shows an exploded side view of the plumbing trap after-valve shown in FIG. 17;  
         [0039]    [0039]FIG. 20 shows an exploded end view of the plumbing trap after-valve shown in FIG. 17;  
         [0040]    [0040]FIG. 21 shows an exploded top view of the plumbing trap after-valve shown in FIG. 17;  
         [0041]    [0041]FIG. 22 a  shows a top view of the plumbing trap after-valve shown in FIG. 17;  
         [0042]    [0042]FIG. 22 b  shows a side view of the plumbing trap after-valve shown in FIG. 17 in the fully open position;  
         [0043]    [0043]FIG. 22 c  shows an end view of the plumbing trap after-valve shown in FIG. 17 in the fully open position;  
         [0044]    [0044]FIG. 23 a  shows a side view of the plumbing trap after-valve shown in FIG. 17 in the fully closed position;  
         [0045]    [0045]FIG. 23 b  shows an end view of the plumbing trap after-valve shown in FIG. 17 in the fully closed position;  
         [0046]    [0046]FIG. 24 shows a top view of plumbing trap apparatus in accordance with a ninth embodiment of the present invention, having a plumbing trap, a section of drain line and a plumbing trap after-valve;  
         [0047]    [0047]FIG. 25 shows a side view of the plumbing trap apparatus shown in FIG. 24, with the plumbing trap after-valve in the fully open position;  
         [0048]    [0048]FIG. 26 shows a side view of the plumbing trap apparatus shown in FIG. 24, with the plumbing trap after-valve in the fully closed position; and  
         [0049]    [0049]FIG. 27 shows optionally included attachment surfaces on two portions of the plumbing trap after-valve. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0050]    Reference is made to FIGS. 9 a  and  9   b , which show a plumbing trap after-valve  10  in accordance with an embodiment of the present invention.  
         [0051]    The plumbing trap after-valve  10  may be located in a drain line  12  downstream from a plumbing trap  14 . Alternatively, the plumbing trap after-valve  10  may be located immediately upstream from the plumbing trap  14 , or even within the trap  14  itself.  
         [0052]    The plumbing trap after-valve  10  is a cleaning assistance apparatus. The installation of the plumbing trap after-valve  10  in the drain line  12  downstream from a plumbing trap  14 , permits the drain line  12  upstream from the plumbing trap  14  to be properly cleaned. The plumbing trap after-valve  10  is a device for shutting off the flow of drain liquids through the drain line  12 .  
         [0053]    The plumbing trap after-valve  10  comprises plunger  16  that may slide inside a plunger housing  18 , between an open position, as shown in FIG. 9 a  and a closed position as shown in FIG. 9 b . The plunger housing  18  may be connected to a portion of the drain line  12 . When the valve  10  is in the open position, the flow of drain liquids through the drain line  12  is unimpeded. When the plumbing trap after-valve  10  is in the closed position, the flow of drain liquids is substantially prevented from passing through the drain line  12 .  
         [0054]    The plunger housing  18  and the plunger  16  may extend vertically upwards from the drain line  12 , downstream from the trap  14 . This will inhibit drain liquids from accumulating in the plunger housing  18  when the valve  10  is in the open position. Alternatively, the plunger housing  18  and the plunger  16  may extend, for example, horizontally outwards from the side of the drain line  12 . As another alternative, they may extend downwards from underneath the drain line  12 , or at any suitable angle from the drain line  12 .  
         [0055]    Reference is made to FIG. 10. A double sink system  20  includes the valve  10 , a pair of sinks  22  and  24 , a drain line  26 , a trap  28  and an optional vent line  30 . The valve  10 , the drain line  26 , the trap  28  and the optionally included vent line  30  make up a plumbing drain system  31 . The drain line  26  includes two drain inlets  32  and  34 , one of which is positioned in each sink  22  and  24 . A first portion  36  of the drain line  26  may extend generally downwards from the drain inlets  32  and  34  to the inlet of the trap  28 . A second portion  38  of the drain line  26  may extend generally horizontally from the outlet of the trap  28  to the vent line  30 . The vent line  30  preferably connects to the top of the drain line  26 , to inhibit the flow of drain liquids therein. A third portion  40  of the drain line  26  extends from the vent line  30  to a drain, such as, for example a municipal drain (not shown).  
         [0056]    The plumbing trap after-valve  10  is shown in the open position. In this position, the sinks may be used as they would normally. Any bad odors originating from the vented drainage system downstream from the trap  28  are blocked by the water  29  in the trap  28  and are thus prevented from escaping out through the drains of the kitchen sinks.  
         [0057]    Reference is made to FIG. 11. After a prolonged period of use, there may be a substantial build-up of matter  42  that is deposited on the inside walls of the drain line  26  upstream from the trap  28 , within the trap  28 , downstream from the trap  28 , and also downstream from the valve  10 . The offensive odors caused by the build-up of matter  42  in the drain line  26  upstream from the trap  28  emanate from the drain inlets  32  and  34  of the sinks  22  and  24 .  
         [0058]    Reference is made to FIGS. 12, 13 and  14 , which illustrate a method for cleaning drain line  26 . Referring to FIG. 12, a first step in the method for cleaning the drain line  26  includes moving the plunger  16  of the valve  10  to the closed position to block off flow in the drain line  26 . Referring to FIG. 13, a second step in the method includes pouring a sufficient amount of cleaning solution  44  into one or both drain inlets  32  and  34  in the sinks  22  and  24 , until the level of cleaning solution  44  reaches the tops of the drain inlets  32  and  34 . As can be seen, the cleaning solution  44  fills all of the drain line  26  that is upstream of the valve  10 , including the plumbing trap  28 , and the cleaning solution substantially remains there until the valve  10  is opened again. Usually about 20 minutes is sufficient time for the cleaning solution  44  to properly attack and destroy the build-up of matter inside the drain line  26  and also inside the plumbing trap  28 .  
         [0059]    Referring to FIG. 14, a third step may be carried out after the desired time has elapsed. The third step comprises opening the valve  10  to release the cleaning solution  44 , including the destroyed remnants of the matter, into the remainder of the vented drainage system and on into the sewers. Finally, the drain line  26  of the sinks  22  and  24  may be flushed through with clean water, and, as shown in FIG. 14, the sinks  22  and  24  may afterwards be clean and fresh and ready for normal use again.  
         [0060]    The offensive odors will have been eliminated because the cleaning solution was provided with a suitable residence time in contact with the build-up of matter  42  to remove substantially all of the matter from the drain line  26  upstream from the trap  28 , within the trap  28 , and between the trap  28  and the valve  10 . Any matter  42  that remains on any of the drain line  26  is located downstream of the valve  10 . Thus, any offensive odors that might originate from such matter  42  would be blocked by the water in the plumbing trap  28 . Furthermore, the matter  42  that is downstream from the valve  10  might be reduced somewhat by the sudden release of cleaning solution  44  when the valve  10  is first re-opened.  
         [0061]    The cleaning of the drain line  26  also improves the capacity of the drain line  26  to transport drain liquids, and reduces the risk of a blockage developing in drain line  26  from a build-up of matter  42 .  
         [0062]    Reference is made to FIG. 15, which shows a plumbing trap after-valve, or cleaning assistance apparatus  50  in accordance with another embodiment of the present invention. Valve  50  is similar to valve  10 , and includes the plunger  16  (see FIG. 16), the plunger housing  18 , and a pass-through conduit  52 , which has, on each end a connector  54  for connecting the valve  50  in-line in a drain line.  
         [0063]    The connectors  54  may be soldered, glued or the like, onto associated portions of drain line that have been inserted into an opening  56  at each end  57  of the pass-through conduit  52 . Alternatively, the connectors  54  may be any suitable means for connecting the valve  50  to a drain line.  
         [0064]    An exploded perspective view of the plumbing trap after-valve  50  is shown in FIG. 16. The plunger  16  may be generally cylindrically-shaped, and may have an outside diameter that is slightly larger than the internal diameter of the plunger housing  18 . The plunger  16  is made of material that is soft but resilient (such as sponge rubber or plastic) so that it can slide smoothly, but tightly, against the inside wall of the plunger housing  18  when the plunger  16  is inserted into the plunger housing  18 . This friction fit ensures that the plunger  16  remains in position at any desired position inside the plunger housing  18 , and also provides a substantially watertight, and airtight, seal between the plunger  16  and the inside wall of the plunger housing  18  when the plunger  16  is in any position therein. The end  58  of the plunger  16  may be hemispherical for mating tightly against the inside wall of the pass-through conduit  52 , for sealing off the pass-through conduit  52  against liquid flow therethrough.  
         [0065]    The generally cylindrical shape of the plunger  16  permits the plunger  16  to be rotated within the valve  10  or  50  so that any selected portion of the plunger surface can be positioned towards the upstream side of the valve  10  or  50 . In this way, the useful service life of the plunger  16  can be extended.  
         [0066]    The plunger  16  may have a handle  60  firmly attached thereto. The handle  60  is the means whereby the plunger  16  is moved into the open and closed positions. The attachment between the plunger  16  and the handle  60  may be made along the full length of that portion of the handle  60  that is inside the plunger  16  to reduce any distortions of the plunger  16  that could interfere with the smooth movement of the plunger  16  inside of the plunger housing  18 . This form of attachment may be attained by means of gluing or fusing the plunger  16  onto the handle  60 , or the like. Alternatively, as shown in FIG. 27, the handle  60  may include a series of ridges  62  that mate with a matching series of ridges  64  that may be molded or otherwise formed into the inside cavity of the plunger  16 .  
         [0067]    The plunger  16  may be made from a smooth-skinned sponge rubber or plastic material that is soft, and resilient, and is capable of withstanding contact with typical cleaning solution chemicals.  
         [0068]    The plunger housing  18  may be formed integrally with the pass-through conduit  52 . The plunger housing  18  may join to the pass-through conduit  52  perpendicularly or at any suitable angle. An end cap  66  may be removably mountable to the free end  68  of the plunger housing  18 . For example, the end cap  66  may be threaded for mating with a corresponding threaded surface at the free end  68 . Alternatively, any suitable releasable connection may be used. By providing a releasable connection for end cap  66 , end cap  66  may be removed so that the plunger  16  can be accessed for replacement or maintenance.  
         [0069]    The end cap  66  may have a hole  70  therethrough at its center for the pass-through of the handle  60 . The end cap  66  provides a sliding engagement with the handle  60 . An optional washer  72  may be included between the end cap  66  and the free end  68  to provide a cushion against which the end cap  66  would be tightened.  
         [0070]    Optionally, as shown in FIG. 15 b , a detachable knob  74  may be fastened onto the free end  76  of the handle  60  to provide a better grip for a user. The knob  74  may be detachable to permit the pass-through of the handle  60  through hole  70  during assembly or disassembly of the valve  50 .  
         [0071]    Reference is made to FIG. 17, and more particularly to FIGS. 18, 19,  20  and  21 , which show a plumbing trap after-valve or cleaning assistance apparatus  80  in accordance with another embodiment of the present invention. The valve  80  is similar to the valve  50  except that the valve  80  includes a compression connector  82  which mates with a threaded portion  84  adjacent each end  57  of the pass-through conduit  52 . The compression connector  82  includes a sleeve  86  and a wedge-shaped packing ring  88 . The sleeve  86  has an internal threaded portion  90 , which mates with one of the threaded portions  84 . The sleeve  86  includes an internal shoulder  92  at its outer end.  
         [0072]    As the sleeve  86  is tightened on the threaded portion  84 , the internal shoulder  92  compresses the wedge-shaped packing ring  88  against the end  57 . The compression of the packing ring  88  causes the packing ring to extend radially inwardly, for sealing against the outside wall of a drain line inserted into the opening  56 .  
         [0073]    Reference is made to FIGS. 22 a ,  22   b  and  22   c , which show a top view, a side view, and an end view of the valve  80  after it has been assembled. As shown, the handle  60  has been pulled fully outwards so that the plunger  16  is positioned entirely within the plunger housing  18 , so that the pass-through conduit  52  is clear of any obstruction. This is the open position of the valve  80 .  
         [0074]    The closed position of the assembled valve  80  is shown in FIGS. 23 a  and  23   b . In this case, the handle  60  has been pushed fully downwards so that the plunger  16  is positioned partly within the plunger housing  18  and partly within the pass-through conduit  52 . The portion of the plunger  16  that is within the pass-through conduit  52  is for blocking off the flow of drain liquids through the pass-through conduit  52 . The portion of the plunger  16  that is within the plunger housing  18  is for providing a watertight seal between the pass-through conduit  52  and the portion of the plunger housing  18  that is above the plunger  16 .  
         [0075]    The foregoing has been a description of a plumbing trap after-valve that would be a totally separate and self-contained device, which can be installed as a unit, in order to be part of a plumbing system. This can be easily done by connecting onto pipes with various connection means that use either soldered, glued, or compression joints.  
         [0076]    Alternatively, an after-valve could be incorporated into a kit of parts for a plumbing trap assembly so as to form a combined trap and valve unit  100 . FIG. 24 shows a top view of such a combination, and FIG. 25 shows a side view of the combination with the valve being in the fully open position. The combined unit  100  includes a trap assembly  102 , a substantially horizontal section of drain line  104  and the plumbing trap after-valve  10 . The trap assembly  102  may have connection means that utilize compression connectors  82  similar to those described with the valve  80 , but it may alternatively have connection means that are soldered, glued, or the like, such as those that have been described with the valve  50 .  
         [0077]    The valve  10  is attached to the top of the horizontal drain line section  104 , downstream from the trap assembly  102 . The horizontal drain line section  104  and the trap assembly  102  may be connected together by means of a different kind of compression connector  83 , which tightens a union-type joint between them to provide a watertight seal. In this case, a vertical tail pipe from the drain of a single sink, or a vertical pipe from the drain line of a double sink, would be inserted into the connector  82  in the upstream end  106  of the trap assembly  102  and a watertight seal would be provided when the sleeve  86  is tightened to compress the packing ring  88  against the inserted pipe, as has been described earlier. Also in this case, the downstream end  108  of the combined trap and after-valve unit  100  may fit into a similar type of compression joint to that used at the upstream end  106 , or by some other means, for connection into the vented drainage system of the house. It will also be understood that the horizontal drain line section  104  and the trap assembly  102  could be integral with one another, with suitable connection fittings at each end.  
         [0078]    With the valve handle  60  pulled outwards, the plunger  16  will be entirely contained within the plunger housing  18 , and the valve  10  will be in its fully open position. When the valve handle  60  is pushed inwards, the plunger  16  will block off the horizontal drain line section  104 , as shown in FIG. 26, and the valve  10  will be in its fully closed position.  
         [0079]    Installation of a shut-off valve, such as the valves  10 ,  50  or  80  upstream from a plumbing trap, within a plumbing trap itself, or preferably downstream from a plumbing trap, for the purpose of selectively preventing the normal passage of waste water through a drain line, facilitates the cleaning of the drain line with a cleaning solution, by permitting the cleaning solution a suitable residence time in contact with matter that is built up on the inside walls of the drain line.  
         [0080]    The valves  10 ,  50  and  80  provide a simple way to shut off waste water flow, while not interfering to the free passage of waste water when fully open. The valves  10 ,  50  and  80  are easy to operate and to maintain, in that the plunger and associated handle are the only moving parts, and can easily be replaced.  
         [0081]    All of the parts of the valves  10 ,  50  and  80 , except for the washer  72  and the plunger  16  may be molded from a hard plastic, or alternatively they may be formed from metal, or some other suitable material.  
         [0082]    Reference is made to FIGS. 5 a  and  5   b , which show a plumbing trap after-valve  110  in accordance with another embodiment of the present invention. The plumbing trap after-valve  110  may have a flap  112  that is centrally pivoted inside a drain line  12  downstream from a plumbing trap  14 .  
         [0083]    Reference is made to FIGS. 6 a  and  6   b  which show a plumbing trap after-valve  114  in accordance with another embodiment of the present invention. The plumbing trap after-valve  114  has an end-pivoted flap  116  which swings up into a cavity  118  located above the drain line  12  when the valve  114  is open so that there is no obstruction to the free flow of waste water in the open position.  
         [0084]    Reference is made to FIGS. 7 a  and  7   b , which show a plumbing trap after-valve  120  in accordance with another embodiment of the present invention. The plumbing trap after-valve  120  comprises a sliding plate  122  that may be located on top of the drain line  12 , downstream from the trap  14 . The plate  122  can be pushed inwards in a guide shaft  123  in order to close off the drain line  12 , and can be pulled outwards in the guide shaft  123  in order to open the drain line  12  to waste water flow.  
         [0085]    Reference is made to FIGS. 8 a  and  8   b , which show a plumbing trap after-valve  124  in accordance with another embodiment of the present invention. The plumbing trap after-valve  124  comprises a rotatable cylindrical plug  126  positioned downstream from the trap  14 . The plug  126  has an outer cylindrical wall  128  and a conduit  130  therethrough, and can be rotated so that either the cylindrical wall  128  is positioned within the drain line  12  to close the valve  124 , or the conduit  130  is aligned with the drain line  12  to open the valve  124 .  
         [0086]    The plumbing trap after-valve may be installed downstream from the plumbing traps of other household appliances, or downstream from the plumbing traps on drain lines in factories, hospitals and institutions.  
         [0087]    While the above description constitutes the preferred embodiments, it will be appreciated that the present invention is susceptible to modification and change without departing from the fair meaning of the accompanying claims.