Abstract:
A Recreational Vehicle tank flush system is provided in which the existing vent pipe to the blackwater tank is modified by attaching an introduction tee which provides a hookup to a source of flushing water and to a hose and sprayer which may be hung just inside the top of the tank.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   None. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   This invention relates to waste tanks, often referred to as black water tanks which collect human waste. Such tanks are often built into recreational vehicles (RVs). Normally, after the tanks fill up they must be drained by attaching an outlet valve to a suitable collection facility. Unfortunately, while this empties the black water tank sufficiently for it to be reused, it does not clean the tank to prevent build-up, odors and fouling of tank quantity transmitters. 
   Currently, owners of such tanks may attempt to clean their black water tanks by connecting an external hose to a water source, dragging the hose to the RV toilet, pushing the probe through the toilet and running water in an attempt to flush the tank. In addition, the hose and probe are now horribly fouled and may represent a risk of contaminating the clean water source. The dirty hose and probe must also be stored. 
   Another method used is to drill a hole through the side of the black water tank and install a nozzle to flush and deodorize the tank. This is invasive and could cause a leak in the tank. 
   A final method is to use the existing drain valve and direct water back through the drain into the waste tank to flush and rinse. Again, this involves a new hose that will be fouled after use and must be stored. Also, very little washing occurs unless the pressurized water has a straight route to the tank. 
   The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. § 1.56(a) exists. 
   BRIEF SUMMARY OF THE INVENTION 
   The invention provides an elegantly simple, effective and safe system to clean black water tanks without any of the detriments of prior approaches. The tank flush system of the invention involves using the vent stack from the tank and builds in a fitting that can be fed clean water from an outside source to the fitting and down into the tank where a spray head directs cleaning water exactly where desired. Retrofitting an existing R/V may be done by cutting into the vent stack and inserting the device. It is a completely built in system with nothing to store. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A detailed description of the invention is hereafter described with specific reference being made to the drawings in which: 
       FIG. 1  is a cross-sectional view of a recreational vehicle showing the inventive tank flush system; 
       FIG. 2  is an enlarged view of the tank flush system of  FIG. 1 ; 
       FIG. 3  is an enlarged view of the sprayer of the tank flush system as it is presented in a black water tank; 
       FIG. 4  is a cross-sectional view of the tank flush system fittings through line  4 - 4  of  FIG. 2 ; 
       FIG. 5  is a cross-sectional view of the tank flush system similar to  FIG. 2  in which the components may be solvent welded together; 
       FIG. 6  is a cross-sectional view of a tank flush system similar to  FIG. 2  in which the fittings are presented as a one piece introduction tee suitable for OEM use. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a stylized Recreational Vehicle or RV  10 . Such RVs include sidewalls  12 , roof  14  and a blackwater tank  16  beneath a toilet which is not shown. The blackwater tank  16  includes a drain  18  to which an external drain connection  20  may be made. The tank  16  includes a vent stack which includes a vent pipe  22  which leads to a vent cap  24 , typically on roof  14  to exhaust any noxious gases produced in the tank  16 . Typically, vent pipe  22  enters tank  16  via flange fitting  26 . 
     FIG. 2  shows how an existing vent pipe has been modified to include a side opening  30 . A clamp-on split side introduction Tee  32  composed of a back half  34  and a mating inlet half  36  having an inlet boss  38  is mated with an elbow fitting  40  that includes a tubing inlet  44  and a tubing outlet  46 . The elbow fitting  40  fits snugly within the inlet boss  38  and descends downwardly within the vent pipe  22  when so fitted. Prior to fitting, a flexible tube  50  is secured to tubing outlet  46  by any suitable manner, such as a clamp  48 . 
     FIG. 3  shows the flexible tube  50  as it descends downwardly into blackwater tank  16 . The free end of tube  50  is attached to a spray fitting  52  which typically includes a tubing nipple  54  to which tube  50  may be secured, as by a clamp  56 . The sprayer  52  may include a lower diverter disk  58  which water would hit and deflect evenly out to the sides of the blackwater tank  16  to rinse any material to the bottom so it may exit the tank via drain  18 . The sprayer  52  may be similar to fire sprinkler system spray heads which are positioned on ceilings in buildings. The sprayer  52  may be of any construction which directs water from tube  50  outwardly to the sides of tank  16 . 
   The tubing inlet  44  of Tee  32  is connected to another tube  60  and secured by a clamp  62  or other securement method. As best shown in  FIG. 1 , the tube  60  exits the sidewall  12  of RV  10  and is suitably secured to the sidewall via a coupling flange  64 . A quick disconnect fitting  66  or other suitable fitting may be used to connect the tank flush system to a source of water. Note that tube  60  may be longer than needed to provide a descending loop that would retain residual water and form a trap  68  to prevent any gases from exiting through fitting  66 . Alternatively, if side venting of gas is not a problem a simple straight tube may be employed. 
     FIGS. 2 and 4  show the introduction tee  32  with an elastomeric gasket  70  and a pair of clamps  72 ,  74  to secure the back half  34  to the inlet half  36  and thereby seal the opening  30 . Other mechanisms may be used to assemble the tee  32  to the vent pipe  22  as are well known in the art. 
     FIG. 5  shows the introduction tee of the invention in an alternative construction in which the tee  80  is a single molded tee as in conventional plumbing tees. It includes the inlet boss  38  and elbow fitting  40  as previously described. However, with a single piece tee  80 , the vent pipe  22  is cut and a section is removed such that the tee  80  may be inserted therebetween with conventional shoulders  82 ,  84  providing the limit for insertion of the cut ends of vent pipe  22 . They may be socket welded or otherwise sealed depending on the materials of the vent pipe and tee  80 . 
   Finally,  FIG. 6  shows a tee  90  formed to include a tee with integral inlet  92  for connection to tube  60  and a tubing outlet  94  for attachment to tube  50 . Tee  90  includes shoulders  82 ,  84  as previously described. As shown, tubing outlet  94  preferably extends beyond the end of tee leg  98  to make it easier to secure tube  50  to outlet  94 . This form of the invention may be readily incorporated into either OEM construction or existing RV units. 
   The invention utilizes the existing vent pipe to provide a simple tank flush system in which water from outside of the RV may be directed from above the blackwater tank into the tank and out toward its walls to flush out the tank. It does not require an additional opening into tank  16  and provides a contamination and leak free system for supplying water to the tank  16 . No hoses are contaminated and fouled by the cleaning system as described in comparison to previous approaches. 
   The introduction tees  32 ,  80  and  90  of the invention all provide a mechanism to connect to the vent pipe  22  and provide a connection to external water which may be directed down through the vent pipe  22  and present a sprayer  52  within tank  16 . 
   While this invention may be embodied in many different forms, there are shown in the drawings and described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
   The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. 
   This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.