Patent Publication Number: US-6209569-B1

Title: Safety shut-off valve assembly for a fuel dispenser

Description:
This is a continuation-in-part of “Adapter Assembly For Accessing Primary Pipeline Of A Double Wall Pipeline System”, Ser. No. 08/933,462, filed Sep. 18, 1997, now U.S. Pat. No. 5,975,110. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a safety shut-off valve assembly for use with a fuel dispenser unit. More particularly, the invention relates to a safety shut-off valve assembly for connecting a terminus of a supply primary pipeline to a ground level gasoline station dispenser unit in a manner whereby periodic assess to the primary pipeline is provided. 
     BACKGROUND OF THE INVENTION 
     Many local, state and federal agencies require that underground storage tank systems for hazardous materials be secondarily contained. The systems generally include an underground tank, a pump containment sump located on top of the tank, and piping from the containment sump to a ground level dispenser unit. Double walled pipeline systems have recently become popular and in some locales are mandated for underground conveyance of the hazardous material. Such pipeline systems include an inner primary pipeline and an outer secondary pipeline for containing any leakage from the primary pipeline. Inclusion of a leak detection means which monitors for leakage from the inner primary pipeline is a further feature which enhances the systems. In fact, the double walled pipeline systems with leak detection capability for the primary pipeline is a cost effective way of meeting governmental leak detection requirements. 
     As a part of mandated safety requirements, many ground level dispenser units have pans, sometimes called dispenser sumps, at their base. The primary pipeline from the underground tank is normally under pressure when any dispenser(s) is dispensing fuel to a vehicle. Therefore, it is necessary to have an emergency safety shut-off valve interposed in the primary pipeline to stop the flow of gasoline in an emergency situation. That is, the valve is designed to close when either the dispenser unit is knocked off its mounting or a fire is started. The pan under each dispenser unit provides an area to access the primary pipeline and to install the safety valve. It also provides an area to access and replace the primary pipeline below the valve as well as to access piping above the valve which leads through the dispenser unit. U.S. Pat. No. 5,098,221, FIG. 7 illustrates a typical safety shut-off valve. 
     Typical dispenser pans result in a large open area under each dispenser unit. The area can collect flammable liquids or vapors which create fire and explosion hazards. The dispenser pans are also prone to fill up with ground water or rain water leaking down into the pan. Some state or local codes prohibit the secondary pipeline of the double walled pipeline system to terminate in an open manner to the interior of the dispenser pan. This is to prevent a collection of liquid or vapors which enters the pan from spreading through the secondary pipe and to the tank containment sump. As readily imagined, this is to prevent the spread of a fire emanating in the dispenser unit to the tank containment sump and possible explosion in the containment sump. The use of dispenser pans is further complicated in that most fire codes require the part of the primary pipeline of the double wall pipeline system which is within the pan to be steel piping or Underwriters Laboratories (UL) fire resistent piping. This means fiberglass and flexible plastic primary piping such as described in U.S. Pat. No. 5,098,221 must terminate underground before entering the dispenser pans. 
     All connector piping used within the dispenser pan must be fire resistent piping. This piping can be considerably more costly than the flexible piping used to convey the liquid from the storage tank to the dispenser pan. Because of leakage of water, flammable liquids or vapors into the dispenser pan, some fire codes require costly leak detection monitoring to detect leaks into the dispenser pan area. As mentioned above, many codes require the secondary pipeline connected to the pan be sealed so as not to let vapors/liquids from the pan into the secondary pipeline or the tank containment sump. In addition to all these requirements and precautions, dispenser pans are difficult and expensive to install in and under the concrete beneath the dispenser unit. They must be installed in a way to prevent rain or ground water from entering the pan. Many pipe and electrical conduit connections which lead into or from the dispenser pan require field installed seals. Historically, these seals have been problem areas of leakage of ground water into pans. Further heightening the problem is the fact it is costly to repair leaks into a dispenser pan during its operational life. 
     There are available dispenser units which do not have a dispenser pan. Secondary piping terminates in a liquid-tight sealed manner to a safety valve located at the dispenser&#39;s base. However, an associated disadvantage with this type of connection is that access to the primary pipeline is impeded. The primary pipeline is subject to deterioration and it is necessary to periodically remove it from within the secondary pipeline and replace it with new piping. Ideally, this is done without having to disconnect or disturb the secondary pipeline in any manner. It is necessary with known present systems to tamper with the secondary pipeline in any primary pipeline replacement process and this, as can be imagined, creates a whole set of new problems. 
     There now has been developed a safety shut-off valve assembly which allows for the installation, removal and replacement of a flexible primary pipeline which is connected to a dispenser unit base without unsealing and/or removing the secondary pipeline under the dispenser unit from the safety shut-off valve assembly. The valve assembly eliminates the need for a fire resistent primary pipeline between the flexible primary pipeline and the safety shut-off valve. The safety shut-off valve assembly further eliminates an accumulation of fuel vapors in the dispenser. 
     SUMMARY OF THE INVENTION 
     A safety shut-off valve assembly is operatively associated with a primary pipeline leading to a dispensing pipeline at a ground level gasoline service station dispenser unit. It can be used with a double wall pipeline system having the primary pipeline for conveying a liquid and a secondary pipeline substantially concentric with the primary pipeline to form an annular space for receiving leakage. The assembly comprises an open-top fuel flow chamber for permanent mounting at a base of the fuel dispenser, a removable cover plate for the open-top fuel flow chamber and having a break-away tube member, and a bonnet valve. The open-top fuel flow chamber has an opening to receive an outlet terminus of the primary supply pipeline as an ingress for the fuel. The break-away tube member in the cover plate has a terminus which serves as an egress through which fuel in the fuel flow chamber passes to the dispensing pipeline in the fuel dispenser unit. The bonnet valve allows the free flow of fuel to pass from the primary pipeline to the dispensing pipeline and shuts off the flow of fuel to the dispensing pipeline upon activation. The bonnet valve is disengageable from the fuel flow chamber to allow access to the primary pipeline for initial installation, removal and replacement purposes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an environmental view partially in section showing a double wall pipeline system and a gasoline service station dispenser unit with a safety shut-off valve assembly of the invention. 
     FIG. 2 is a side elevational view partially in section showing in detail the safety shut-off valve assembly of FIG.  1 . 
     FIG. 3 is a top plan view partially in section of the safety shut-off valve assembly of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The safety shut-off valve assembly of the invention finds its greatest use with ground level dispenser units such as found at retail gasoline service stations for filling fuel tanks of vehicles. For this reason, the shut-off valve assembly is described below and is illustrated in the drawings with reference to such dispenser units. It can as well be used with other dispenser units which control the flow of liquid from a bulk storage tank or other containment means and which dispense to commercial vehicles or other machinery. 
     The safety shut-off valve assembly of the invention is operably associated with the base of a gasoline dispenser unit. It is interposed between a primary supply pipeline and a dispensing pipeline in the dispenser unit. Most importantly, the safety shut-off valve assembly provides a means to install, remove and replace the primary pipeline from a double wall pipeline system without a need to disconnect the secondary pipeline. It also eliminates the need for a fire resistant connector pipeline between the primary supply pipeline and the dispensing pipeline. 
     As used herein, “base” of the dispenser unit is used to indicate a structure located at or below ground surface level and underneath the dispenser unit. Bases include a (1) a bottom well wall of the dispenser unit itself and (2) a concrete body, with or without a rigid island form, at an island station on which the dispenser unit is mounted. Removal of the dispenser unit or a side panel to the dispenser unit will typically expose the safety shut-off valve assembly of the invention. 
     With reference to FIG. 1, there is shown a safety shut-off valve assembly  10  of the invention positioned at the base of a dispenser unit  11 . The base is a concrete body  12  and, as shown, preferably includes a bottom wall of a rigid island form  13  used in formation of a concrete island structure  14 . The dispenser unit  11  itself is mounted on the concrete island structure  14 . The concrete island structure extends up to about twelve inches above ground surface. It helps to protect the dispenser unit  11  and pipelines within and leading to it from damage by a vehicle. One or more drain holes  15  are preferably provided leading through the island form  13  and concrete island structure  14 , to primarily drain rain water or leaked liquid which may collect within the area under the dispenser unit onto a concrete pad  16  of the service station. 
     The rigid island form  13  is used in formation of the concrete island structure and normally remains in the concrete body  12 . The island form  13  is made of metal, though other materials rigid enough to retain their shape during formation of the dispenser unit base can be used. Together, the concrete body  12  and the bottom wall of the island form  13  provide the base of the dispenser unit depicted in FIGS. 1 and 2. 
     The dispenser unit  11  is secured to the concrete island structure  14  over the island form  13 . The safety shut-off valve assembly  10  is at or below the top surface of the concrete island structure  14 . As further discussed below the valve is designed to shut-off or close the primary pipeline upon the occurrence of a bumping sufficiently hard to cause structural damage or a fire at the dispenser unit. Further flow of gasoline from the primary supply pipeline to the dispensing pipeline within the dispenser unit is stopped. 
     The dispenser unit  11  has a panel (not shown) to access its interior for routine maintenance work on any component of the unit and to access the safety shut-off valve assembly and the primary pipeline. Gasoline hoses with fueling nozzles and a control panel are also a part of the dispenser unit and operate conventionally. 
     Still with reference to FIG. 1, an underground storage tank  18  is used to store the gasoline. It typically has a capacity of 10,000 to 20,000 gallons liquid, though can be smaller or larger. An access way  19  extends downwardly from ground surface, through the concrete pad  16 , and to the top surface of the storage tank  18 . A removable cover  20  is used to enter the access way  19  for periodic maintenance work on a pump  21  positioned in the access way  19  or piping  22  connecting the pump  21  to the storage tank  18 . Access ways are further described in U.S. Pat. Nos. 5,134,878 and 5,136,877. 
     As shown, a double wall pipeline system  23  leads from the pump  21  through a wall of the access way  19  and to a distribution box  24 . A manifold (not shown) or other distribution means within the distribution box  24  splits the flow of gasoline into separate pipelines which lead directly to one or more (two as shown) dispenser units  11 . Alternatively, the access way  19  can serve as a distribution box with a distal end of the secondary pipeline beginning at the access way&#39;s wall. The pipeline system  23  could also be a single wall primary pipeline. 
     As best seen in FIG. 2, the double wall pipeline system  23  includes a primary supply pipeline  25  which conveys the gasoline and a larger diameter secondary pipeline  26  substantially concentric therewith. The secondary pipeline serves to contain any gasoline which may leak from the primary pipeline. An annular space  27  is formed between the primary and secondary pipelines. The primary pipeline is semi-rigid or flexible in nature and is made of any suitable material, e.g. a plastic such as polyethylene, nylon, nitrel or tetrafluoroethylene (available as Teflon) or a metal such as soft copper or aluminum or fluted stainless steel. Rolled or fluted tubing is particularly attractive in that it can be readily pulled through the secondary pipeline. Preferably, while not illustrated, a leak detection system is operably connected to the annular space between the primary and secondary pipelines to detect the presence of leaked liquid, e.g. gasoline or ground water. Any leakage detection is conveyed to a monitoring station to alert the station owner/operator to the problem. Necessarily, all terminuses of both the primary pipeline and secondary pipeline of the double wall pipeline system are sealed in a liquid-tight manner. 
     The built-in safety shut-off valve assembly  10  is easy to install and is reliable. It is interposed between the primary pipeline  25  and the dispensing pipeline  28 . The safety shut-off valve assembly comprises an open-top fuel flow chamber member  30 , a removable cover plate  31  dimensioned to overlie the fuel flow chamber member  30  and a bonnet valve  32 . The open-top fuel flow chamber member  30  is shown as permanently mounted in the concrete island structure  14 . It is directly below the dispenser unit  11 . The fuel flow chamber member  30  has a base and upstanding walls to form a chamber area  33  to hold fuel as further discussed below. 
     The removable cover plate  31  overlies the chamber area  33  of the fuel flow chamber member  30  and is bolted to it. A break-away tube member  34  extends from the cover plate  31 . As shown, it is integral with the cover plate and extends vertically. Its lower terminus is an egress for fuel flowing through the fuel flow chamber member  30 . Its upper terminus is connected to the dispensing pipeline and for this reason a set of internal threads are provided. As evident, a base  35  of the break-away tube member  34  above the cover plate  31  is thin walled so that any force exerted on the break-away tube member  34  will cause it to break or at least bend. The break-away tube member  34  can end at the cover plate or, as shown, extend downwardly from the cover plate&#39;s underside into the chamber area  33 . 
     The cover plate  31  and break-away tube member  34  can be one-piece as shown with a mid-portion  36  of the cover plate  31  recessed downwardly to accommodate a trigger arm as described below. The cover plate  31  and break-away tube member  34  can also be two discreet structures which are joined together. For example, the cover plate  31  can have a centrally disposed threaded hole and the break-away tube member  34  be externally threaded. The one-piece integral structure is preferred because of an elimination of any sealing means which would be needed with a two piece structure to prevent fuel escaping from the chamber area  33 . 
     The safety shut-off valve assembly  10  also includes the bonnet valve  32  to control the flow of fuel to the break-away tube member  34 . The bonnet valve has a substantially flat plate disc  37  dimensioned to fully cover the terminus of the break-away tube member  34 . In the open state, fuel freely flows through the opening of the break-away tube member  34  as it egresses the fuel chamber area  33 . In the closed state, the plate disc  37  is urged into contact with the opening to prevent further fuel flow therethrough. The plate disc  37  has a lower annular lip  38  to receive and retain an upper end of a spring  40 . It also has an approximately centered guide post  39  extending vertically. As evident in FIG. 2, the bonnet valve includes the spring  40  to urge the plate disc  37  upwardly upon activation. The spring  40  is positioned over a spring form tube  41  to hold a lower end in position. Other means of urging the plate disc of the bonnet valve to mate with the terminus of the break-away tube member  34  to close it off can be used. 
     The bonnet valve  32  also includes a trigger arm  43  which is mounted on the break-away tube member  34  and is operably associated with the plate disc  37  of the bonnet valve. It forces the plate disc  37  and spring  40  downwardly to permit flow of fuel through the primary pipeline, and into the dispensing pipeline of the dispenser unit. 
     The trigger arm  43  is a rod bent in a mid-section to give an approximate right angle with a first section  44  extending generally vertically along the break-away tube member  34  and a second section  45  extending generally horizontally into an interior area of the tube member. It is configured to normally hold the plate disc  37  of the bonnet valve down, yet move with the break-away tube member  34  in case of an accident so as to break contact with the plate disc  37 . The trigger arm  43  has a looped end  46  at its upper terminus. A retention pin  47  secured to the break-away tube member  34  extends laterally and is used to receive the looped end  46 . A hole  48  in the tube member&#39;s side wall receives the second section and along with the retention pin  47  holds the trigger arm in place. A seal  49  in the hole ensures no fuel leakage. 
     A set of guide arms  50  extend substantially horizontally inwardly from the lower terminus of the break-away tube member  34 . The guide arms  50  receive the centered guide post  39  on the plate disc  37  to hold the bonnet valve in position. 
     It should be readily apparent that a bumping of sufficient force will cause the break-away tube member  34  to bend or break-off and then trip the trigger arm  43 . This in turn releases the plate disc  37  of the bonnet valve to move upwardly into blocking contact with the break-away tube member terminus to effectively close off further liquid flow from the primary pipeline. 
     The trigger arm  43 , at least in an exposed area, is optionally made of a meltable material such as solder. In case of a fire, the solder melts to release the bonnet valve. 
     Of particular importance, a complete unit is available which effectively prevents accidental spills. The chamber area  33  of the fuel flow chamber member  30  is substantially filled with gasoline and, because of a lack of sufficient oxygen, will not catch fire. At the same time, the chamber area can be emptied for ready access to the primary pipeline when needed. 
     As aforementioned, the safety shut-off valve assembly of the invention can be used with a primary pipeline which is the sole pipeline or with a primary pipeline which has a concentric secondary pipeline. In the later case, preferably an adaptor assembly is used. The adaptor assembly  60  depicted in FIG. 2 comprises a casing  61 , a coupling  62  and a disengageable seal system  63 . The casing  61  has an upper cylinder and a smaller diameter lower cylinder. The coupling  62  is a short tubular member which fits into a terminal end of the primary pipeline  25 . A flared end is preferably provided for use of installation purposes. The coupling primarily acts as a rigid backing to prevent collapse of the primary terminus. The disengageable seal system  63  includes a compressible annular member  64  which provides a compression seal on both its inner wall surface which is in contact with the primary pipeline  25  and on its outer wall surface which is in contact with the casing  61 . The annular member  64  is made of a compressible material, e.g. a synthetic elastomeric material and is dimensioned to fit at least partially into and substantially fill the space within the upper cylinder of the casing  61 . An annular ram seat  65  fits over the coupling  62  and primary pipeline  25  and sits on top of the compressible annular member  64 . The ram seat is an annular flat rigid member. A ram nut  66  is externally threaded to engage threads in the ingress opening in the fuel flow chamber  30  and to impart a force onto the ram seat  65  to hold the compressible annular member  64  in place during use. While not necessary, the ram seat  65  prevents the compressible annular member  64  from spreading outwardly or inwardly and is preferably used for this reason. Still other adaptor assemblies are described in U.S. Pat. No. 5,975,110 and are incorporated by reference herein. 
     In use, the dispenser unit having the safety shut-off valve assembly of the invention dispenses fuel as normal. Fuel flows from an underground storage tank through the primary supply pipeline to the dispenser&#39;s base. The fuel flows into fuel flow chamber and then continues to flow through the break-away tube member and into the dispensing pipeline. If the dispenser unit is bumped or otherwise disturbed, the bonnet valve is activated. That is, the plate member of the bonnet valve is urged into contact with the terminus of the break-away tube member to prevent egress of fuel into the dispenser unit. 
     When it is necessary to check and/or replace the primary pipeline, access to the safety shut-off valve assembly of the invention is readily gained, normally by an access panel on the dispenser unit. The cover plate is removed. The bonnet valve is then removed to reveal the primary pipeline. The primary pipeline can be disconnected at its terminuses and replaced if need be. 
     While several embodiments of the invention have been described in detail and with reference to the drawings, still other embodiments to accomplish the same purpose are contemplated. Such embodiments and all changes or modifications of an obvious nature are considered within the scope of the appended claims.