Patent Abstract:
An exemplary embodiment of the invention is a kit for installing an underground piping system. The kit includes a protective conduit having flexible piping contained therein and a plurality of sealing members. The installer positions the protective conduit and flexible piping as a single unit thereby facilitating installation.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/488,136 filed Jan. 20, 2000, now U.S. Pat. No. 6,315,003 the entire contents of which are incorporated herein by reference, and claims the benefit of U.S. provisional application Ser. No. 60/116,770 filed Jan. 22, 1999, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates generally to piping systems and in particular to an underground piping system using flexible gas piping. Currently, flexible gas piping, such as corrugated stainless steel tubing (CSST), is used in underground applications or received in concrete slabs. Various plumbing and mechanical codes require that such installations of CSST be protected. Typically, protective conduit is placed in underground installations and the flexible piping is positioned in the protective conduit by pulling the flexible piping through the protective conduit. Pulling the flexible piping through the protective conduit creates excess labor and increases the cost of installing flexible piping. 
     SUMMARY OF THE INVENTION 
     The above-discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the underground piping system of the present invention. An exemplary embodiment of the invention is a kit for installing an underground piping system. The kit includes a protective conduit having flexible piping contained therein and a plurality of sealing members. The installer positions the protective conduit and flexible piping as a single unit thereby facilitating installation. 
     The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: 
     FIG. 1 is a partial cross-sectional view of an underground piping system and fitting in an exemplary embodiment of the invention; 
     FIGS. 2-4 illustrate steps in installing the underground piping system; 
     FIG. 5 is a side view of an alternate embodiment of the invention; and, 
     FIG. 6 is a cross sectional view of an alternate embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a side view, in partial cross-section, of an underground piping system and fitting in an exemplary embodiment of the invention. The underground piping system includes flexible piping  12  (such as CSST), a protective conduit  14  and a sealing member  16 . Flexible piping  12  may include a jacket (not shown). A conventional fitting  10  maybe connected to the flexible piping  12 . The protective conduit  14  is a made from a semi-rigid material in order to protect the flexible piping  12  while still allowing the protective conduit  14  to be coiled for easy handling and transportation. In an exemplary embodiment, protective conduit  14  is made from polyethylene. Sealing member  16  seals the gap between the inner diameter of the protective conduit  14  and the outside surface of the flexible piping  12 . This contains gas within the gas-impermeable protective conduit  14 . In an exemplary embodiment, the sealing member  16  is a heat shrink polyolefin. A heat source, such as a heat gun, is used to shrink the sealing member  16  to the protective conduit  14  and the flexible piping  12  or the jacket of the flexible piping  12  if so equipped. 
     Installation of the underground piping system will now be described with reference to FIGS. 2-4. The underground piping system of the invention may be supplied in a kit containing a predetermined length (e.g. 100 feet or longer) of flexible piping  12  positioned within a similar length of protective conduit  14  and two sealing members  16 . FIG. 2 depicts the flexible piping  12  positioned within the protective conduit  14 . In an exemplary embodiment, the protective conduit has a cylindrical cross section. As noted above, the flexible piping  12  is positioned within the protective conduit  14  to eliminate the need to pull the flexible piping  12  through the protective conduit  14 . The first step of the installation procedure is to remove a portion of the protective conduit  14 . This is done using a standard tubing cutter and results in flexible piping  12  extending beyond the protective conduit  14  as shown in FIG.  3 . At this point, the flexible piping  12  may be cut to a desired length. 
     The next step is to place sealing member  16  over the end of the protective conduit  14  such that the sealing member  16  covers both the protective conduit  14  and the flexible piping  12  as shown in FIG.  4 . In an exemplary embodiment, sealing member  16  has a cylindrical cross section and has an inner diameter slighter larger than the outer diameter of protective conduit  14 . In an exemplary embodiment, a three inch length of sealing member  16  is used. The sealing member  16  is then heated with an appropriate heat source (e.g. heat gun) such that the sealing member contracts and seals against both the flexible piping  12  (or piping jacket) and the protective conduit  14  as shown in FIG.  1 . The other end of the flexible piping  12  and protective conduit  14  may be prepared in a similar fashion. A fitting, such as fitting  10  in FIG. 1, may then be attached to the flexible piping  12  as is known in the art. If necessary, the flexible piping  12  can be removed from the protective conduit  14  after installation by removing sealing members  16  and pulling the flexible piping  12  from the protective conduit  14 . 
     FIG. 5 shows an alternate embodiment of the invention which uses a corrugated protective conduit  15 . Also shown in FIG. 5 is the jacket  13  of the flexible piping  12  described above. The corrugated protective conduit  15  may be made from polyethylene. The jacket  13  may also be made from polyethylene. The corrugated protective conduit  15  provides more flexibility than the cylindrical protective conduit  14  described above with reference to FIGS. 1-4. 
     FIG. 6 shows another alternative embodiment of the invention. As shown in FIG. 6, the underground piping system includes a vent member shown generally at  20 . Certain regulations may require that the protective conduit  14  be vented. The vent member  20  provides for compliance with such regulations. As shown in FIG. 6, the vent member  20  is implemented, in one embodiment of the invention, using a tee joint  22 . A first end  24  of the tee joint  22  is connected to the protective conduit  14  using known techniques such as adhesives. A vent opening  28  in vent tee  22  allows gas to escape from the protective conduit  14 . The second end  26  of the vent tee  22  may be sealed directly to the flexible tubing  12 ′ using a sealing member  16 ′ contacting jacket  13 ′. Alternatively, the system may include an extension protective conduit  30  which is connected to the second end  26  of the vent tee  22  using known techniques. The extension protective conduit  30  is then sealed to the jacket  13  of flexible piping  12  by a sealing member  16 . 
     The present invention provides an underground piping system which facilitates installation. The invention may be embodied in a kit including a protective conduit having flexible piping positioned therein, sealing members and vent tees if necessary. Although, the invention has been described with respect to underground installations, it is understood that it is applicable to installations in concrete slabs and similar installations were protection of the flexible piping is needed. 
     While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

Technology Classification (CPC): 5