Abstract:
An under dispenser containment system with integral penetration fitting and a fitting support structure separate from the sump. The containment system is adapted for use under fuel dispensers. The containment system comprises a double-walled sump with apertures and lips surrounding the apertures molded into the inner and outer walls. The containment system also comprises a fitting support structure that is not attached to the sump to allow replacement of the support structure without having to replace the sump.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an under dispenser containment system (“UDC”) for use under a fuel dispenser such as the kind used to dispense gasoline, diesel or aviation fuel. The system includes quasi-integral penetration fittings and a shear valve support structure separate from the sump portion of the UDC. The UDC is double-walled and made of polyethylene. 
       BACKGROUND OF THE INVENTION 
       [0002]    Fuel such as gasoline, diesel and aviation fuel is typically stored in large underground storage tanks (“USTs”) and transported by a pump through underground piping to the area below above-ground fuel dispensers. At that point, the underground piping makes a turn to run vertically upward toward the fuel dispenser. Typically, a shear valve is located near the base of the dispenser. The shear valve closes off the fuel pipe to prevent massive fuel leaks in the event that the fuel pipe above the shear valve is broken which can occur, for example, if the fuel dispenser is hit by a car. 
         [0003]    Many jurisdictions, require the fuel to be secondarily contained to reduce the possibility of fuel leaking from the fuel handling equipment into the environment. Thus, UST&#39;s are typically double-walled with an inner wall that contains the fuel and an outer wall intended to contain any fuel that may leak through openings in the inner wall. Underground piping also is typically double-walled with an inner pipe that contains the fuel and an outer pipe intended to contain any fuel that may leak from the inner pipe. The interstitial space between the inner and outer wall of the UST and the underground piping may be monitored to detect leaks in either the inner or outer wall. Such monitoring may be accomplished by placing the interstitial space under vacuum and monitoring the vacuum pressure or filling the interstitial space with inert fluid and monitoring the level of the inert fluid. The underground piping typically is constructed from either fiberglass or polyethylene (“PE”). PE piping offers certain advantages over fiberglass piping in that PE is more flexible while fiberglass is more brittle. Fiberglass, however, is easier to bond with other materials making it easier to obtain solid connections that do not leak. 
         [0004]    Under the fuel dispenser, the secondary containment is typically provided by an under dispenser containment (“UDC”) system. The shear valves are typically located within the sump portion of the UDC. The internal piping of the dispenser is located above the sump such that any leaks from the internal piping will fall into and be contained within the sump. Examples of UDCs are shown in U.S. Pat. Nos. 4,842,163, 5,246,044 and 5,301,722. 
         [0005]    Historically, UDCs have presented several challenges. The piping that carries the fuel must pass through the UDC. In most UDC systems, the penetration apertures in the sump are cut at the installation site to allow the apertures to be placed in the proper locations with respect to the underground pipes. Cutting the apertures at the installation site increases the time and complexity of the installation. In addition, such penetrations are difficult to seal against leaks. Thus, the penetrations are usually located on the side of the sump rather than the bottom so that if the penetration is not sealed properly, no liquid fuel will leak through the penetration unless the liquid fuel fills the sump to at or above the level of the penetrations. If the underground piping in a fuel facility is made from fiberglass, many jurisdictions require a four-foot run of pipe from the exterior of the sump before a fitting may be placed on the pipe. Examples of such fittings might include an angled fitting to change the direction of the pipe or a straight connection to connect to a second length of underground pipe. If a four-foot run is required, the penetration is typically made in the side of the sump to avoid having to excavate to a depth of four feet below the bottom of the sump and run the fuel piping connecting to the USTs at an excessive depth. 
         [0006]    One example of an attempt to deal with the propensity of such penetrations to leak is found in U.S. Pat. No. 5,246,044 (“Robertson”). Robertson discloses a fiberglass UDC with integral fiberglass couplings that penetrate the bottom of the UDC. The most common method of sealing a penetration fitting is a bulkhead style penetration fitting. One example of such a fitting is disclosed in U.S. Pat. No. 5,285,829. Use of bulkhead style fittings requires the UDC to be relatively large to allow the installer easy access to the interior of the UDC to install the portion of the bulkhead fitting located inside the UDC. With such larger UDCs, PE&#39;s flexibility presents a problem. If a relatively larger UDC is made of PE, the pressure from the surrounding dirt and concrete once the UDC is installed can cause the UDC to bend, buckle or collapse. 
         [0007]    A second function of the UDC is to assist with providing support and bracing for the shear valves and internal piping of the dispenser. Typically, the support for the shear valves is connected to the sump portion of the UDC. For example, U.S. Pat. No. 4,842,163 discloses a “U” shaped brace that connects the shear valve to the side of the UDC. Robertson discloses shear valve support members connected to brackets attached to the UDC. One disadvantage of a connection between the shear valve and the UDC is that damage to the shear valve or internal piping, such as an impact by a car, usually results in damage to the UDC. That problem is particularly prevalent if the UDC is made of fiberglass because of its rigid properties. Thus, after such damage the entire UDC has to be replaced. Such replacement usually requires excavation, usually including breaking and re-pouring concrete surrounding the UDC. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention presents a UDC system that overcomes many of problems addressed above. The sump portion of the UDC is double-walled and made of PE. The penetration apertures are pre-molded in the inner and outer walls at the bottom of the sump portion of the UDC. Lips are provided around the edge of the apertures in both the internal wall and the external wall. In the preferred embodiment, double-walled PE pipes are placed in the penetration apertures and fittings are applied that fuse the outer wall of the pipe to the lips around the aperture providing what is essentially an integral penetration fitting. In addition, the lip around the penetration aperture in the internal wall reduces the chance that liquid fuel will leak out of the interior of the UDC in the event of a fuel spill and a failure of the fusion fitting. 
         [0009]    The exterior end of the penetration pipe is connected to the underground fuel piping. The interior end of the penetration fitting is connected to a shear valve. The provision of the penetration pipes already installed in the sump portion of the UDC means that the total size of the sump can be smaller than those currently in use as there is no need to have easy access to the interior of the UDC to install bulkhead style fittings. The smaller size allows the UDC to maintain structural integrity even though it is made from PE. The provision of the penetration pipes and smaller size also allows the sump portion of the UDC to be replaced without the need to break and repour concrete. 
         [0010]    The UDC system also is provided with a support rack for the shear valves and internal piping that is independent from sump portion of the UDC system. Anchors for the support rack are embedded in the concrete next to the upper lip of the UDC. A collar is connected to the anchors. The shear valves are held by the collar. The combination of a PE sump and a shear valve support rack independent from the sump in the disclosed system provides important advantages over the current state of the art. In the event of trauma to the dispenser, such as the dispenser being struck by a car, the internal piping of the dispenser will likely be damaged along with the mechanism providing support for the shear valves. In the current state of the art, the shear valve support structures are integral with the sump portion of the UDC. Thus, damage to the shear valve support structure frequently causes damage to the sump requiring replacement of both the sump and the support structure. Sumps in current use typically have a relatively narrow opening in the top and a wider body to allow room for workmen to work inside the sump. That structure results in the sump having “shoulders” that are typically covered with concrete. Thus, replacement of the sump usually requires excavation including breaking and re-pouring concrete. 
         [0011]    In contrast to the current state of the art, the support structure for the shear valves of the disclosed UDC system is completely independent from the sump portion of the UDC. In addition, the sump portion of the UDC is made of PE which is flexible. Thus, in the event of trauma to the dispenser and damage to the shear valve support structure, the support structure usually can be removed and replaced without the need to break and re-pour concrete. In addition, the flexible properties of the PE sump portion typically allow the sump to absorb any trauma by flexing and springing back into position without any damage to the sump. Finally, the disclosed sump has no “shoulders” but rather straight sides and a lip that is intended to be located at ground level. Thus, should the sump portion need to be replaced, the sump can be lifted out after cutting the bottom of the sump around the penetration pipes. A new sump with openings appropriately sized to accommodate the existing penetration pipes and attached portions of the previous sump may be lowered into the existing hole and the joints sealed by hand welding or other known method. Such replacement may be done without the need to break and re-pour the surrounding concrete. 
         [0012]    The present UDC system presents an additional advantage over the state of the art. As discussed, conventional practice when installing a UDC is to drill the penetration apertures at the location of installation and to install penetration fittings, such as bulkhead fittings, to seal the penetration points. In the preferred embodiment of the present UDC system, the penetrations are pre-installed with PE double-walled pipes extending through the sump and downward from the bottom of the sump portion. The UDC systems may be delivered in a frame that may be buried. Thus, installation may involve simply excavating a hole of an appropriate size and dropping the UDC system including the support structure into the hole. The underground piping is connected to the double-walled penetration pipes of the disclosed UDC system with conventional fittings that are used to connect one piece of underground pipe to another such as elbow or angle fittings. Thus, the disclosed UDC system greatly simplifies the installation process and reduces the chances of human error during the installation resulting in savings of time and money. The double-walled PE pipes of the present UDC system are easily attached to underground piping made of PE. The flexible properties of PE make it a preferable material for underground piping as compared with fiberglass underground piping. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a front view of a fuel dispenser and a cut-away front view of one embodiment of the UDC system installed beneath the fuel dispenser; 
           [0014]      FIG. 2  is a front view of one embodiment of the UDC system; 
           [0015]      FIG. 3  is a side cut-away view of one embodiment of the UDC system along line  3 - 3  of  FIG. 2 ; 
           [0016]      FIG. 4  is a plan view of one embodiment of the UDC system; 
           [0017]      FIG. 5  is a side cut-away view of one embodiment of the UDC system along line  5 - 5  of  FIG. 4 ; 
           [0018]      FIG. 6  is an enlarged detailed view of one embodiment of the penetration fitting as indicated in  FIG. 5 ; 
           [0019]      FIG. 7  is a perspective view showing one embodiment of the UDC system including the support structure installed in earth and concrete; and 
           [0020]      FIG. 8  is a front view of a fuel dispenser and a cut-away front view of a prior art sump installed beneath the fuel dispenser. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    In accordance with the preferred embodiment of the present invention, as shown in  FIG. 1 , the UDC system, indicated generally as  10 , is shown installed beneath fuel dispenser  12 . Support rack  14  is connected to anchors  16  by bolts  18 . Anchors  16  are embedded in concrete  20  poured on top of earth  22 . Sump, indicated generally as  24 , rests on earth  22  and is encased in concrete  20 . UDC  10  is installed so that lip  60  of sump  24  is approximately level with the top of concrete  20 . Fuel pipes  26  connect to penetration pipes  28  that pass through penetration fittings  30 . Shear valves  32  are connected to the upper end of penetration pipes  28  and connected to rack  14  by brackets  34 . Additional views of the foregoing components of the UDC system are shown in  FIGS. 2 and 3 . 
         [0022]    As shown in  FIGS. 3 and 5 , sump portion  24  has an outer wall  36  and an inner wall  38  creating an interstitial space  40  that may be monitored for leaks in walls  36  and  38 . 
         [0023]    As shown in  FIGS. 3 ,  4  and  5 , support rack  14  may comprise two main L-shaped beams running either side of shear valves  32 . Support rack  14  is connected to anchors  16  by bolts  18 . Shear valves  32  are connected to support rack  14  by brackets  34 . In the event of damage to support rack  14 , such as might occur should dispenser  12  be hit by a car, bolts  18  may be removed, brackets  34  disconnected and rack  14  replaced without the need to remove and replace sump  24 . 
         [0024]      FIG. 6  shows a detail view of a penetration fitting  30 . Penetration pipe, designated generally as  28 , has an inner wall  42  and an outer wall  44  defining an interstitial space  46  that may be monitored for leaks in walls  42  or  44 . The outer wall  36  of sump  24  is formed into an annular lip  48  that surrounds an aperture in outer wall  36  through which penetration pipe  28  passes. Similarly, inner wall  38  of sump  24  is formed into an annular lip  50  that surrounds an aperture in inner wall  38 . 
         [0025]    Cuff  52  is placed over and contains lip  48  and penetration pipe  28  where penetration pipe  28  passes through the aperture formed by lip  48 . Cuff  52  contains internal heating elements that, when activated, partially melt those portions of cuff  52  that contact the outer wall  44  of penetration pipe  28  and lip  48  forming a permanent sealed bond with outer wall  44  and lip  48 . Similarly, cuff  54  is placed over and contains lip  50  and penetration pipe  28  where penetration pipe  28  passes through the aperture formed by lip  50 . Cuff  54  contains internal heating elements that, when activated, partially melt those portions of cuff  54  that contact the outer wall  44  of penetration pipe  28  and lip  50  forming a permanent sealed bond with outer wall  44  and lip  50 . The bonding of lip  50 , cuff  54  and outer wall  44  provides a sealed interior bottom surface of sump  24  that will catch and hold any fuel that may escape from the shear valves  32  or internal piping of the dispenser. Furthermore, in the event cuff  54  fails to bond completely to lip  50  and outer wall  44  or such bond fails at some point in time, lip  50  provides some protection against leaks as any fluid would need to build up in the bottom of sump  24  to a height above lip  50  before such fluid could leak through the aperture defined by lip  50 . In such an event, the fluid would still be contained within sump  24  in the interstitial space  40 . Monitoring of interstitial space  40  by known means would alert interested parties to any failure at any point in penetration  30 . 
         [0026]      FIG. 7  shows the UDC system  10  installed in a typical fueling station environment and illustrates the convenient installation of the UDC system. Anchors  16  are partially embedded in concrete  20 . Support rack  14  is connected to anchors  16  by bolts  18 . Sump  24  is supported by support frame  56  and, after concrete  20  is poured, lip  60 . To install UDC system  10 , a hole is dug in earth  22  that is large enough and deep enough to accommodate sump  24 , support frame  56  and the portion of penetration pipes  28  that extend below sump  24 . Before and during installation, anchors  16  and connected support rack  14  may be held in place at the appropriate level with respect to sump  24  by bands  58  that connect anchors  16  to support frame  56 . UDC system  10  and support frame  56  are lowered into the hole and penetration pipes  28  are connected to fuel pipes  26  by conventional means. The hole is then backfilled and concrete  20  is poured. 
         [0027]    Should it become necessary to replace support rack  14 , support rack  14  may be disconnected from anchors  16  by removing bolts  18 . Shear valves  32  are disconnected from brackets  34  and support rack  14  may be removed and replaced. 
         [0028]    With reference to  FIG. 6 , should it become necessary to replace sump  24 , support rack  14  is removed as described above, an annular cut may be made in inner wall  38  around each penetration pipe  28 . A second annular cut may be made in outer wall  36  around each penetration pipe  28 . Once the penetration pipes  28  have been separated from the walls of sump  24 , sump  24  may be lifted out. A new sump  24  with holes in its inner wall  38  and outer wall  36  sized appropriately to accommodate penetration pipes  28  may be dropped into the hole. Penetration pipes  28  may be connected to outer wall  36  and inner wall  38  with annular patches and hand welding. 
         [0029]    As shown in  FIG. 8 , typical prior art sumps such as sump  64  have shoulders  62  that are covered with concrete  20  which must be removed and repoured if the sump  64  is to be replaced. The replacement of sump  24  and support rack  14  in the disclosed UDC system  10  may be accomplished without the need to break and re-pour the concrete  20  surrounding UDC system  10  which greatly simplifies the replacement process saving both time and money and allowing the dispenser  12  to be put back into service much more quickly than is possible in the case of prior art UDC systems.