Patent Abstract:
A fueling environment that distributes fuel from a fuel supply to fuel dispensers in a daisy chain arrangement with a double walled piping system. Fuel leaks that occur within the double walled piping system are returned to the underground storage tank by the outer wall of the double walled piping. This preserves the fuel for later use and helps reduce the risk of environmental contamination. Leak detectors may also be positioned in fuel dispensers detect leaks and provide alarms for the operator and help pinpoint leak detection that has occurred in the piping system proximate to a particular fuel dispenser or in between two consecutive fuel dispensers.

Full Description:
RELATED APPLICATION 
   The present application is a continuation of U.S. patent application Ser. No. 10/173,990, filed Jun. 18, 2002, which is hereby incorporated by reference in its entirety. 

   FIELD OF THE INVENTION 
   The present invention relates to a fuel recovery system for recovery leaks that occur in fuel supply piping in a retail fueling environment. 
   BACKGROUND OF THE INVENTION 
   Managing fuel leaks in fueling environments has become more and more important in recent years as both state and federal agencies impose strict regulations requiring fueling systems to be monitored for leaks. Initially, the regulations required double walled tanks for storing fuel accompanied by leak detection for the tanks. Subsequently, the regulatory agencies have become concerned with the piping between the underground storage tank and the fuel dispensers and are requiring double walled piping throughout the fueling environment as well. 
   Typically, the double walled piping that extends between fuel handling elements within the fueling environment terminates at each end with a sump that is open to the atmosphere. In the event of a leak, the outer pipe fills and spills into the sump. The sump likewise catches other debris, such as water and contaminants that contaminate the fuel caught by the sump, thereby making this contaminated fuel unusable. Thus, the sump is isolated from the underground storage tank, and fuel captured by the sump is effectively lost. 
   Coupled with the regulatory changes in the requirements for the fluid containment vessels are requirements for leak monitoring such that the chances of fuel escaping to the environment are minimized. Typical leak detection devices are positioned in the sumps. These leak detection devices may be probes or the like and may be connected to a control system for the fueling environment such that the fuel dispensing is shut down when a leak is detected. 
   Until now, fueling environments have been equipped with elements from a myriad of suppliers. Fuel dispensers might be supplied by one company, the underground storage tanks by a second company, the fuel supply piping by a third company, and the tank monitoring equipment by yet a fourth company. This makes the job of the designer and installer of the fueling environment harder as compatibility issues and the like come into play. Further, it is difficult for one company to require a specific leak detection program with its products. Interoperability of components in a fueling environment may provide economic synergies to the company able to effectuate such, and provide better, more integrated leak detection opportunities. 
   Any fuel piping system that is installed for use in a fueling environment should advantageously reduce the risk of environmental contamination when a leak occurs and attempt to recapture fuel that leaks for reuse and to reduce excavation costs, further reducing the likelihood of environmental contamination. Still further, such a system should include redundancy features and help reduce the costs of clean up. 
   SUMMARY OF THE INVENTION 
   The present invention capitalizes on the synergies created between the tank monitoring equipment, the submersible turbine pump (STP), and the fuel dispenser in a fueling environment. A fluid connection that carries a fuel supply for eventual delivery to a vehicle is made between the underground storage tank and the fuel dispensers via double walled piping. Rather than use the conventional sumps and low point drains, the present invention drains any fuel that has leaked from the main conduit of the double walled piping back to the underground storage tank. This addresses the need to recapture the fuel for reuse and to reduce fuel that is stored in sumps which must later be retrieved and excavated by costly service personnel. 
   The fluid in the outer conduit may drain to the underground storage tank by gravity coupled with the appropriately sloping piping arrangements, or a vacuum may be applied to the outer conduit from the vacuum in the underground storage tank. The vacuum will drain the outer conduit. Further, the return path may be fluidly isolated from the sumps, thus protecting the fuel from contamination. 
   In an exemplary embodiment, the fuel dispensers are connected to one another via a daisy chain fuel piping arrangement rather than by a known main and branch conduit arrangement. Fuel supplied to a first fuel dispenser by the STP and conduit is carried forward to other fuel dispensers coupled to the first fuel dispenser via the daisy chain fuel piping arrangement. The daisy chain is achieved by a T-intersection contained within a manifold in each fuel dispenser. Fuel leaking in the double walled piping is returned through the piping network through each downstream fuel dispenser before being returned to the underground storage tank. 
   The daisy chain arrangement allows for leak detection probes to be placed within each fuel dispenser so that leaks between the fuel dispensers may be detected. The multiplicity of probes causes leak detection redundancy and helps pinpoint where the leak is occurring. Further, the multiple probes help detect fuel leaks in the outer conduit of the double walled piping. This is accomplished by verifying that fuel dispensers downstream of a detected leak also detect a leak. If they do not, a sensor has failed or the outer conduit has failed. A failure in the outer piping is cause for serious concern as fuel may be escaping to the environment and a corresponding alarm may be generated. 
   Another possibility with the present invention is to isolate sumps, if still present within the fuel dispenser, from this return path of captured leaking fuel such that contaminants are precluded from entering the leaked fuel before being returned to the underground storage tank. In this manner, fuel may potentially be reused since it is not contaminated by other contaminants, such as water, and reclamation efforts are easier. Since the fuel is returned to the underground storage tank, there is less danger that a sump overflows and allows the fuel to escape into the environment. 
   Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention. 
       FIG. 1  illustrates a conventional communication system within a fueling environment in the prior art; 
       FIG. 2  illustrates a conventional fueling path layout in a fueling environment in the prior art; 
       FIG. 3  illustrates, according to an exemplary embodiment of the present invention, a daisy chain configuration for a fueling path in a fueling environment; 
       FIG. 4  illustrates, according to an exemplary embodiment of the present invention, a fuel dispenser; 
       FIG. 5  illustrates a first embodiment of a fuel return to underground storage tank arrangement; 
       FIG. 6  illustrates a second embodiment of a fuel return to underground storage tank arrangement; and 
       FIG. 7  illustrates a flow chart showing the leak detection functionality of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. 
   Fueling environments come in many different designs. Before describing the particular aspects of the present invention (which begins at the description of  FIG. 3 ), a brief description of a fueling environment follows. A conventional exemplary fueling environment  10  is illustrated in  FIGS. 1 and 2 . Such a fueling environment  10  may comprise a central building  12 , a car wash  14 , and a plurality of fueling islands  16 . 
   The central building  12  need not be centrally located within the fueling environment  10 , but rather is the focus of the fueling environment  10 , and may house a convenience store  18  and/or a quick serve restaurant  20  therein. Both the convenience store  18  and the quick serve restaurant  20  may include a point of sale  22 ,  24 , respectively. The central building  12  may further house a site controller (SC)  26 , which in an exemplary embodiment may be the G-SITE® sold by Gilbarco Inc. of Greensboro, N.C. The site controller  26  may control the authorization of fueling transactions and other conventional activities as is well understood. The site controller  26  may be incorporated into a point of sale, such as point of sale  22  if needed or desired. Further, the site controller  26  may have an off-site communication link  28  allowing communication with a remote location for credit/debit card authorization, content provision, reporting purposes or the like, as needed or desired. The off-site communication link  28  may be routed through the Public Switched Telephone Network (PSTN), the Internet, both, or the like, as needed or desired. 
   The car wash  14  may have a point of sale  30  associated therewith that communicates with the site controller  26  for inventory and/or sales purposes. The car wash  14  alternatively may be a stand alone unit. Note that the car wash  14 , the convenience store  18 , and the quick serve restaurant  18  are all optional and need not be present in a given fueling environment. 
   The fueling islands  16  may have one or more fuel dispensers  32  positioned thereon. The fuel dispensers  32  may be, for example, the ECLIPSE® or ENCORE® sold by Gilbarco Inc. of Greensboro, N.C. The fuel dispensers  32  are in electronic communication with the site controller  26  through a LAN or the like. 
   The fueling environment  10  also has one or more underground storage tanks  34  adapted to hold fuel therein. As such the underground storage tank  34  may be a double walled tank. Further, each underground storage tank  34  may include a tank monitor (TM)  36  associated therewith. The tank monitors  36  may communicate with the fuel dispensers  32  (either through the site controller  26  or directly, as needed or desired) to determine amounts of fuel dispensed and compare fuel dispensed to current levels of fuel within the underground storage tanks  34  to determine if the underground storage tanks  34  are leaking. 
   The tank monitor  36  may communicate with the site controller  26  and further may have an off-site communication link  38  for leak detection reporting, inventory reporting, or the like. Much like the off-site communication link  28 , off-site communication link  38  may be through the PSTN, the Internet, both, or the like. If the off-site communication link  28  is present, the off-site communication link  38  need not be present and vice versa, although both links may be present if needed or desired. As used herein, the tank monitor  36  and the site controller  26  are site communicators to the extent that they allow off site communication and report site data to a remote location. 
   For further information on how elements of a fueling environment  10  may interact, reference is made to U.S. Pat. No. 5,956,259, which is hereby incorporated by reference in its entirety. Information about fuel dispensers may be found in commonly owned U.S. Pat. Nos. 5,734,851 and 6,052,629, which are hereby incorporated by reference in their entirety. Information about car washes may be found in commonly owned U.S. patent application Ser. No. 60/380,111, filed 6 May 2002, entitled SERVICE STATION CAR WASH, which is hereby incorporated by reference in its entirety. An exemplary tank monitor  36  is the TLS-350R manufactured and sold by Veeder-Root. For more information about tank monitors  36  and their operation, reference is made to U.S. Pat. Nos. 5,423,457; 5,400,253; 5,319,545; and 4,977,528, which are hereby incorporated by reference in their entireties. 
   In addition to the various conventional communication links between the elements of the fueling environment  10 , there are conventional fluid connections to distribute fuel about the fueling environment as illustrated in  FIG. 2 . Underground storage tanks  34  may each be associated with a vent  40  that allows over-pressurized tanks to relieve pressure thereby. A pressure valve (not shown) is placed on the outlet side of each vent  40  to open to atmosphere when the underground storage tank  34  reaches a predetermined pressure threshold. Additionally, under-pressurized tanks may draw air in through the vents  40 . In an exemplary embodiment, two underground storage tanks  34  exist—one a low octane tank ( 87 ) and one a high octane tank ( 93 ). Blending may be performed within the fuel dispensers  32  as is well understood to achieve an intermediate grade of fuel. Alternatively, additional underground storage tanks  34  may be provided for diesel and/or an intermediate grade of fuel (not shown). 
   Pipes  42  connect the underground storage tanks  34  to the fuel dispensers  32 . Pipes  42  may be arranged in a main conduit  44  and branch conduit  46  configuration, where the main conduit  44  carries the fuel to the branch conduits  46 , and the branch conduits  46  connect to the fuel dispensers  32 . Typically, pipes  42  are double walled pipes comprising an inner conduit and an outer conduit. Fuel flows in the inner conduit to the fuel dispensers, and the outer conduit insulates the environment from leaks in the inner conduit. For a better explanation of such pipes and concerns about how they are connected, reference is made to Chapter B13 of PIPING HANDBOOK, 7 th  edition, copyright 2000, published by McGraw-Hill, which is hereby incorporated by reference. 
   In a typical service station installation, leak detection may be performed by a variety of techniques, including probes and leak detection cables. More information about such devices can be found in the previously incorporated PIPING HANDBOOK. Conventional installations do not return to the underground storage tank  34  fuel that leaks from the inner conduit to the outer conduit, but rather allow the fuel to be captured in low point sumps, trenches, or the like, where the fuel mixes with contaminants such as dirt, water and the like, thereby ruining the fuel for future use without processing. 
   While not shown, vapor recovery systems may also be integrated into the fueling environment  10  with vapor recovered from fueling operations being returned to the underground storage tanks  34  via separate vapor recovery lines (not shown). For more information on vapor recovery systems, the interested reader is directed to U.S. Pat. Nos. 5,040,577; 6,170,539; and Re. 35,238, and U.S. patent application Ser. No. 09/783,178 filed 14 Feb. 2001, all of which are hereby incorporated by reference in their entireties. 
   Now turning to the present invention, the main and branch supply conduit arrangement of  FIG. 2  is replaced by a daisy chain fuel supply arrangement as illustrated in  FIG. 3 . The underground storage tank  34  provides a fuel delivery path to a first fuel dispenser  32   1  via a double walled pipe  48 . The first fuel dispenser  32   1  is configured to allow the fuel delivery path to continue onto a second fuel dispenser  32   2  via a daisy chaining double walled pipe  50 . The process repeats until an nth fuel dispenser  32   n  is reached. Each fuel dispenser  32  has a manifold  52  with an inlet aperture and an outlet aperture as will be better explained below. In the nth fuel dispenser  32   n , the outlet aperture is terminated conventionally as described in the previously incorporated PIPING HANDBOOK. 
   As better illustrated in  FIG. 4 , each fuel dispenser  32  comprises a manifold  52  with a T-intersection housed therein. The T-intersection  54  allows the fuel line conduit  56  to be stubbed out of the daisy chaining double walled pipe  50  and particularly to extend through the outer wall  58  of the daisy chaining double walled pipe  50 . This T-intersection  54  may be a conventional T-intersection such as is found in the previously incorporated PIPING HANDBOOK. The manifold  52  comprises the aforementioned inlt aperture  60  and outlet aperture  62 . While shown on the sides of the manifold  52 &#39;s housing, they could equivalently be on the bottom side of the manifold  52 , if desired. Please note that the present invention is not limited to a manifold  52  with a T-joint, and that any other suitable configuration may be used that allows fuel to be supplied to a fuel dispenser  32  and allows to continue on as well to the next fuel dispenser  32  until the last fuel dispenser  32  is reached. 
   A leak detection probe  64  may also be positioned within the manifold  52 . This leak detection probe  64  may be any appropriate liquid detection sensor as needed or desired. The fuel dispenser  32  has conventional fuel handling components  66  therein, such as fuel pump  68 , a vapor recovery system  70 , a fueling hose  72 , a blender  74 , a flow meter  76 , and a fueling nozzle  78 . Other fuel handling components  66  may also be present as is well understood in the art. 
   With this arrangement, the fuel may flow into the fuel dispenser  32  in the fuel line conduit  56 , passing through the inlet aperture  60  of the manifold  52 . A check valve  80  may be used if needed or desired as is well understood to prevent fuel from flowing backwards. The fuel handling components  66  draw fuel through the check valve  80  and into the handling area of the fuel dispenser  32 . Fuel that is not needed for that fuel dispenser  32  is passed through the manifold  52  upstream to the other fuel dispensers  32  within the daisy chain. A sump (not shown) may still be associated with the fuel dispenser  32 , but it is fluidly isolated from the daisy chaining double walled pipe  50 . 
   A first embodiment of the connection of the daisy chaining double walled pipe  50  to the underground storage tank  34  is illustrated in  FIG. 5 . The daisy chaining double walled pipe  50  connects to a casing construction  82 , which in turn connects to the double walled pipe  48 . A submersible turbine pump  84  is positioned within the underground storage tank  34 , preferably below the level of the fuel  86  within the underground storage tank  34 . For a more complete exploration of the casing construction  82  and the submersible turbine pump  84 , reference is made to U.S. Pat. No. 6,223,765 assigned to Marley Pump Company, which is incorporated herein by reference in its entirety and the product exemplifying the teachings of the patent explained in  Quantum Submersible Pump Manual: Installation and Operation , also produced by the Marley Pump Company, also incorporated by reference in its entirety. In this embodiment, fuel captured by the outer wall  58  is returned to the casing construction  82  such as through a vacuum or by gravity feeds. A valve (not shown) may allow the fuel to pass into the casing construction  82  and thereby be connected to the double walled pipe  48  for return to the underground storage tank  34 . The structure of the casing construction in the &#39;765 patent is well suited for this purpose having multiple paths by which fuel may be returned to the outer wall of the double walled pipe that connects the casing construction  82  to the submersible turbine pump  84 . 
   A second embodiment of the connection of the daisy chaining double walled pipe  50  to the underground storage tank  34  is illustrated in  FIG. 6 . The casing construction  82  is substantially identical to the previously incorporated U.S. Pat. No. 6,223,765. The daisy chaining double walled pipe  50  however comprises a fluid connection  88  to the double walled pipe  48 . This allows the fuel in the outer wall  58  to drain directly to the underground storage tank  34 , instead of having to provide a return path through the casing construction  82 . Further, the continuous fluid connection from the underground storage tank  34  to the outer wall  58  causes any vacuum present in the underground storage tank  34  to also be existent in the outer wall  58  of the daisy chaining double walled pipe  50 . This vacuum may help drain the fuel back to the underground storage tank  34 . In an exemplary embodiment, the fluid connection  88  may also be double walled so as to comply with any appropriate regulations. 
     FIG. 7  illustrates the methodology of the present invention. During new construction of the fueling environment  10 , or perhaps when adding the present invention to an existing fueling environment  10 , the daisy chained piping system according to the present invention is installed (block  100 ). The pipe connection between the first fuel dispenser  32   1  and the underground storage tank  34  may, in an exemplary embodiment, be sloped such that gravity assists the drainage from the fuel dispenser  32  to the underground storage tank  34 . The leak detection system, and particularly, the leak detection probes  64 , are installed in the manifolds  52  of the fuel dispensers  32  (block  102 ). Note that the leak detection probes  64  may be installed during construction of the fuel dispensers  32  or retrofit as needed. In any event, the leak detection probes  64  may communicate with the site communicators such as the site controller  26  or the tank monitor  36  as needed or desired. This communication may be for alarm purposes, calibration purposes, testing purposes or the like as needed or desired. Additionally, this communication may pass through the site communicator to a remote location if needed. Further, note that additional leak detectors (not shown) may be installed for redundancies and/or positioned in the sumps of the fuel dispensers  32 . Still further, leak detection programs may be existent to determine if the underground storage tank  34  is leaking. These additional leak detection devices may likewise communicate with the site communicator as needed or desired. 
   The fueling environment  10  operates as is conventional, with fuel being dispensed to vehicles, vapor recovered, consumers interacting with the points of sale, and the operator generating revenue (block  104 ). At some point a leak occurs between two fuel dispensers  32   x  and  32   x+1 . Alternatively, the leak may occur at a fuel dispenser  32   x+1  (block  106 ). The leaking fuel flows towards the underground storage tank  34  (block  108 ), as a function of the vacuum existent in the outer wall  58 , via gravity or the like. The leak is detected at the first downstream leak detection probe  64  (block  110 ). Thus, in the two examples, the leak would be detected by the leak detection probe  64  positioned within the fuel dispenser  32   x . This helps in pinpointing the leak. An alarm may be generated (block  112 ). This alarm may be reported to the site controller  26 , the tank monitor  36  or other location as needed or desired. 
   A second leak detection probe  64 , positioned downstream of the first leak detection probe  64  in the fuel dispenser  32   x−1 , will then detect the leaking fuel as it flows past the second leak detection probe  64  (block  114 ). This continues, with the leak detection probe  64  in each fuel dispenser  32  downstream of the leak detecting the leak until fuel dispenser  32   1  detects the leak. The fuel is then returned to the underground storage tank  34  (block  116 ). 
   If all downstream leak detection probes  64  detect the leak at query block  118 , that is indicative that the system works (block  120 ). If a downstream leak detection probe  64  fails to detect the leak during the query of block  118 , then there is potentially a failure in the outer wall  58  and an alarm may be generated (block  122 ). Further, if the leak detection probes  64  associated with fuel dispensers  32   x+1  and  32   x−1  both detect the leak, but the leak detection probe  64  associated with the fuel dispenser  32   x  does not detect a leak, that is indicative of a sensor failure and a second type of alarm may be generated. 
   Additionally, once a leak is detected and the alarm is generated, the fueling environment  10  may shut down so that clean up and repair can begin. However, if the double walled piping system works the way it should, the only repair will be to the leaking section of inner pipe within the daisy chaining double walled pipe  50  or the leaking fuel dispenser  32 . Any fuel may caught by the outer wall  58  is returned for reuse, thus saving on clean up. 
   Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Technology Classification (CPC): 8