Abstract:
Disclosed is a dual stop valve assembly for use in a cargo tank motor vehicle having a flammable material stowing cargo tank with an external pipe for dispensing the flammable material (e.g., chemicals). The assembly includes an a dual stop valve assembly for use in a cargo tank motor vehicle having a flammable material stowing cargo tank with an external pipe for dispensing the flammable material. The assembly includes an external pipe connection section for connecting the external pipe to the cargo tank; a first stop valve positioned within the external pipe connection section; a second stop valves spaced apart from the first stop valve and positioned within the external pipe connection section; and an actuator for moving the pair of stop valves between a material transport position and a flammable material loading and unloading position. The external pipe connection section includes a break area for promoting breakage of the external pipe connection section along the break area such that, upon breakage along the break area, only an amount of flammable material that is stowed within the external pipe connection section and between the pair of stop valves is discharged. Advantageously, the present invention provides for improved safety in the transport of flammable liquids by providing an apparatus and method for reducing the amount of flammable liquids released in the event of a breakaway event. Moreover, the assembly can be made such that it does not includes any external linkages for effecting movement of the valves.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. Ser. No. 10/864,169, filed Jun. 9, 2004, pending, which also claims the benefit of the filing dates of U.S. application Ser. Nos. 60/477,174 and 60/486,954, filed on Jun. 9, 2003 and Jul. 14, 2003, respectively. 
     
    
     FIELD AND BACKGROUND OF THE INVENTION  
       [0002]     The invention relates generally to petroleum product transportation safety devices, and more particularly to a valve assembly for cargo tank motor vehicles having wet lines.  
         [0003]     Cargo tank motor vehicles, specifically models MC 306 and DOT 406, are frequently used in the over-the-road transportation and conveyance of gasoline, fuel oil and other petroleum products. Since Sep. 1, 1995, cargo tank motor vehicles have been required to meet DOT 406 specifications. These types of cargo tanks are low pressure (less than 5 psi) with a cargo capacity generally between 9,000 and 10,000 gallons. With such a large cargo of flammable materials, cargo tank integrity is of high concern, and improvements that enhance the safe transportation of such flammable products are of interest in the industry and to the general public.  
         [0004]     Cargo tanks are normally filled by pumping product through external piping. The external piping can carry 30-50 gallons of gasoline or other flammable products from the time of initial loading, through transport, until a first delivery stop. During transport, then, the external pipes are filled with product or are wet, with this condition being known in the industry as having “wet lines”.  
         [0005]     However, it has been found that the present systems and processes preclude the evacuation of gasoline in the external lines following loading of the product. Presently, the external lines are drained only after the individual cargo compartments have been unloaded of product during delivery, and then only by gravity. The net result is that the external lines of undelivered cargo compartments remain full of product during transportation.  
         [0006]     Generally, cargo tank integrity is protected from collisions that include the external piping through the use of shear sections (sacrificial device) on the external piping that fail first in the event of an accident, and by internal valves to stop the flow of product.  
         [0007]     The wet lines condition that exists presently on the cargo tank motor vehicles can make the vehicles vulnerable in side impact collisions involving the external piping of the cargo tank motor vehicles. Clearances (generally 2′ to 4′) between the cargo tank vehicles and the roadway also provide spacing for automobiles to underride the cargo tank in a side collision, resulting in potential damage to the external piping.  
         [0008]     In recent years, this condition has been of concern to the National Transportation Safety Board and the Research and Special Programs Administration of the United States Department of Transportation, culminating in proposed rulemaking to reduce safety risks associated with the transportation of flammable liquids in unprotected product piping. Therefore, there is a great recognition in the industry to solve the wet lines problem presently in existence.  
         [0009]     The need currently exists to be able to reduce the risk posed by wet lines. Additionally, it has been found that there is a lack of a solution acceptable to all affected parties to the wet lines problem that involves isolation of the flammable liquids contained within the outlet piping assemblies on cargo tank motor vehicles, and within the cargo tank.  
         [0010]     Another need that has been identified in the solving of the above problems is the safe and economical retrofitting of existing trailers in service with any new designs. To that end, it would be beneficial if proposed design solutions were dimensionally similar to stop valves currently in service on cargo tankers.  
         [0011]     Therefore, an invention solving the aforementioned problems would be highly desirable.  
       BRIEF SUMMARY OF THE INVENTION  
       [0012]     Disclosed herein is a dual stop valve assembly for use in a cargo tank motor vehicle having a flammable material stowing cargo tank with an external pipe for dispensing the flammable material. The assembly comprises an external pipe connection section for connecting the external pipe to the cargo tank; a pair of stop valves spaced apart and operable within the external pipe connection section; and an actuator for actuating opening of each of the pair of stop valves between a material transport position and a flammable material loading/unloading position. The external pipe connection section includes a break area for promoting breakage of the external pipe connection section along the break area such that, upon breakage along the break area, only an amount of flammable material that is stowed within the external pipe connection section and between the pair of stop valves is discharged.  
         [0013]     Other objects, aspects, and advantages of the invention will be apparent upon a thorough reading of the detailed description below along with the drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     Embodiments of the invention are disclosed with reference to the accompanying drawings and are for illustrative purposes only. The invention is not limited in its application to the details of construction or the arrangement of the components illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in other various ways. Like reference numerals are used to indicate like components. In the drawings:  
         [0015]      FIG. 1  is a schematic side view of a cargo tank motor vehicle having a cargo tank incorporating the present invention;  
         [0016]      FIG. 2  is an enlarged view of one embodiment of an inventive dual stop valve assembly shown in an open position and taken along line  2 - 2  of  FIG. 1 ;  
         [0017]      FIG. 3  is a cross-sectional view of one embodiment of the dual stop valve assembly shown in an open position;  
         [0018]      FIG. 4  is a cross-sectional view of one embodiment of the dual stop valve assembly shown in a closed position;  
         [0019]      FIG. 5  is an enlarged view similar to  FIG. 2  with the inventive dual stop valve assembly shown in a closed position;  
         [0020]      FIG. 6  is an enlarged portion of one embodiment of the dual stop valve assembly taken along line  6 - 6  of  FIG. 4  showing a shear section;  
         [0021]      FIG. 7  is an enlarged view similar to  FIG. 5  illustrating the inventive dual stop valve assembly during breakaway;  
         [0022]      FIG. 8  is a cross-sectional cutaway view of the dual stop valve assembly showing the upper valve assembly portion  64   a  post breakaway;  
         [0023]      FIG. 9  is a schematic cross-sectional view taken along line  9 - 9  of  FIG. 8 ;  
         [0024]      FIG. 10  is a cross-sectional view of another embodiment of the dual stop valve assembly;  
         [0025]      FIG. 11  is an enlarged portion of an embodiment of the dual stop valve assembly taken along line  11 - 11  of  FIG. 10 ;  
         [0026]      FIG. 12  is a cross-sectional view of another embodiment of the dual stop valve assembly in accordance with the present invention;  
         [0027]      FIG. 13  is an enlarged portion of an embodiment of the dual stop valve assembly taken along line  13 - 13  of  FIG. 12 ;  
         [0028]      FIG. 14  is a cross-sectional view of another embodiment of the dual stop valve assembly in accordance with the present invention;  
         [0029]      FIG. 15  is a cross-sectional view of another embodiment of the dual stop valve assembly in accordance with the present invention; and  
         [0030]      FIG. 16  is a cross-sectional view of another embodiment of the dual stop valve assembly in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]      FIG. 1  is a schematic side view of a cargo tank motor vehicle  10  having a cab  12  and a cargo tank trailer  14  connectable thereto. Trailer  14  includes a cargo tank  16  for holding and transporting a material. In the embodiment shown, the tank includes several compartments or sections  18   a - d , and thus, the tank is capable of transporting a plurality of materials. The materials for which the invention is designed include petroleum products (e.g., gasoline, fuel oil, kerosene) or other hazardous or flammable products. Exemplary cargo tank motor vehicles contemplated for use with the present invention include MC306 and DOT406 vehicles. Such vehicles can be constructed from mild or stainless steel, or aluminum (e.g., desirable due to it low weight) and typically have a cargo capacity of between 9000 and 10000 gallons. Each cargo tank section  18   a - d  is connected to an external pipe  20   a - d  through which the contents of the individual section are pumped in or drawn out. Each external pipe  20   a - d  terminates in a spigot or valve  22  to dispense the respective material held in the respective tank section. Connecting each external pipe  20   a - d  to each cargo section  18   a - d  are inventive valve assemblies  24 ,  26 ,  28  and  30 . The valve assemblies, as can be seen, are positioned below the cargo sections and thus are vulnerable to impact (and particularly side impacts) from, for example, another motor vehicle. Such impacts result in wet lines and the associated discharge of hazardous material from the piping. It is a significant aspect of the present invention that the present inventive valve assemblies, whether newly installed or part of a retrofit assembly, will serve to isolate and protect wet lines in cargo tankers and thus minimize discharge of hazardous products.  
         [0032]      FIG. 2  is an enlarged view of one embodiment of an inventive dual stop valve assembly  30  (also called a dual closing stop valve assembly) shown in an open position and taken along line  2 - 2  of  FIG. 1 . The dual stop valve assembly is connected to the cargo tanker ( FIG. 1 ) and to an external pipe  20   d . The assembly  30  is situated between the external pipe  20   d  and cargo tank section  18   d  and is connected thereto via a flange section  32 . The assembly is connected to the pipe  20   d  via connecter  34 .  
         [0033]      FIG. 3  is a cross-sectional view of one embodiment of the dual stop valve assembly  30  shown in an open position and  FIG. 4  is a cross-sectional view of one embodiment of the dual stop valve shown in a closed position. The dual stop valve assembly  30  includes an external pipe connection section  36  for connecting the external pipe (via connector  34 ) to the cargo tank  18 , and more specifically cargo tank section  18   d . The assembly  30  further includes a pair of stop valves  38   a - b  spaced and operable within the external pipe connection section  36 . One of the pair of stop valves  38   a  is for sealing and containing a flammable material within the cargo tank section  18   d  and the other of the pair of stop valves  38   b  is for sealing and containing the flammable material within, primarily within, the external pipe  36 . An actuator  40  (see  FIG. 2 ) is used for actuating opening of each of the pair stop valves  38   a - b  between a material transport position ( FIG. 4 ) in which the valves are closed and a flammable material loading/unloading position ( FIG. 3 ) in which the valves are open. Both valves are self-closing by means of spring action. The external pipe connection section  36  includes a break area  42  (also called a “shear section”) for promoting sacrificial breakage of the external pipe connection section along the break area such that, upon breakage along the break area, only an amount of flammable material that is stowed within the external pipe connection section and between the pair of stop valves is discharged.  
         [0034]     Referring to  FIGS. 2-4 , in this embodiment, actuator  40  is secured in a known fashion to the external pipe connection section  36 , and is further mechanically connected to impart motion to valves  38   a - b  via linkage arms  48   a - b . Linkage arm  50  is connected to linkage  48   a - b  so as to synchronize motion of the arms, and ultimately, the valves between open and closed positions, as illustrated in  FIGS. 3 and 4  respectively. The actuator can take various forms, such as mechanical, hydraulic or pneumatic. The actuator can also be referred to as actuating means.  
         [0035]     In the embodiment illustrated, valves  38   a - b  are rotatable about their respective pivot point  52   a - b  located at the center of spindles  56   a - b  such that the valves rotate in same directions (i.e., as shown, valves  38   a - b  rotate in counterclockwise fashion when the valves are opened during loading/unloading of material into or out of the cargo tank as shown in  FIG. 3  and valves  38   a - b  rotate in clockwise fashion to achieve a closed position suitable during material transport as shown in  FIG. 4 ). Stated another way, the spindles are located on opposite sides of the external pipe section such that, when the poppets are opened and closed, the spindles rotate in the same direction. Self-closing spring return assemblies  54   a - b  are used to facilitate, in conjunction with the actuator, opening and closing of the valves  38   a - b  as they rotate about spindles  56   a - b . Stop valves  38   a - b  further include lift forks  58   a - b , to which O-ring or other seals or sealing means  60   a - b  and poppets  62   a - b  are connected in a known fashion. Advantageously, each of the plurality of linkage arms is individually removable for leakage testing of each of the pair of valves individually to ensure valve-seal integrity.  
         [0036]      FIG. 6  is an enlarged portion of one embodiment of the dual, stop valve taken along line  6 - 6  of  FIG. 4 , specifically showing shear section  42 . As illustrated, the shear section includes a notch-shaped groove  44  that runs substantially about an outer perimeter of a wall  46  of the shear section  42 . It is contemplated that the shear section can take on other shapes or forms, however, the shear section is generally defined or characterized by an area of reduced material or reduced material thickness. Such reduction results in a line or area of weakness that when, by way of example, an impact or force is applied to a generalized region encompassing the material reduction area, breakage is promoted (i.e., likely to occur) along the area. Such breakaway (also called a “breakaway event”) will occur, by definition, at a force that is below a force necessary to break adjoining non-shear section areas of the external pipe connection section  36 .  
         [0037]      FIG. 5  is an enlarged view similar to  FIG. 2  with the inventive dual stop valve assembly  30  shown in the material transport or closed position. As noted above,  FIG. 6  is an enlarged portion of one embodiment of the dual stop valve assembly showing the shear section. And  FIG. 7  is an enlarged view similar to  FIG. 5  illustrating the inventive dual stop valve assembly during breakaway. During an impact that causes breakaway (i.e., a breakaway impact), dual stop valve assembly  30  breaks along shear section  44  into a first or upper dual stop valve assembly portion  64   a  and a second or lower dual stop valve assembly portion  64   b . More specifically, as shown, linkage  50  may become dislodged to permit the lower portion  64   b  to fall away and, in conjunction with the closing of the stop valves (and in particular valve  38   b ), contain material with the external pipe  20   d . In addition, upper  64   a  remains connected to the cargo tanker section  18   d . As a result, even if an impact causes dual stop valve assembly to be dislodged from its associated cargo tank section and translated to a resting position, the flammable contents will be effectively isolated from potential ignition sources. That is, only a nominal volume of flammable liquids (i.e., the contents encapsulated between the poppets of the stop valve) would possibly be released. Stated another way, only a small quantity (i.e., about a cup or less) of material (i.e., material located in the area between the stop valves) is dispensed or released.  
         [0038]      FIG. 8  is a cross-sectional cutaway view of the dual stop valve assembly showing the upper valve assembly portion  64   a  post breakaway.  FIG. 9  is a schematic cross-sectional view taken along line  9 - 9  of  FIG. 8 . As shown, valve  38   a  is in a closed position so as to seal flammable material within cargo section  18   d . Shown in phantom is actuator  40 , which again, accomplishes the opening of the valve. Valve assembly again includes flange section  32  having holes  66  for permitting connection of the assembly to the cargo tank section  18   d , as by bolts or other connection means  68 .  
         [0039]      FIG. 10  is a cross-sectional view of another embodiment of the dual stop valve  130  and  FIG. 11  is an enlarged portion of an embodiment of the dual stop valve taken along line  11 - 11  of  FIG. 10 . This embodiment still includes two stop valves  138   a - b , however in this instance, the valves are situated so that valve  138   a  is located over valve  138   b . In this embodiment, the valves rotate about their respective spindles  156   a - b  such that they now rotate in opposite directions when moving from their closed position shown, or open position (shown in phantom). Stated another way, the spindles are located on opposite sides of the external pipe section such that, when the poppets are opened and closed, the spindles rotate in opposite directions. As illustrated, the shear section includes a vertex  145  and two flat section  147   a - b  to create a groove  144  that runs substantially about an outer perimeter of a wall  146  of the shear section  142 . The groove again constitutes an area of reduced material or reduced material thickness to promote breakaway.  
         [0040]      FIG. 12  is a cross-sectional view of another embodiment of the dual stop valve  230  in accordance with the present invention and  FIG. 13  is an enlarged portion of an embodiment of the dual stop valve taken along line  13 - 13  of  FIG. 12 . In this embodiment, the valve assembly  230  includes a first valve  238   a  comprising a poppet and a second valve  238   b  of the butterfly variety, which is situated within a disc  239  to form a disc assembly  240 . The principal of operation is similar to that described above in that both valves move simultaneously (or substantially simultaneously) from their closed position during transport and their open position during loading/unloading (shown in phantom), with a shear section  242  disposed between the valves. As illustrated, the shear section includes a notched groove  244  that runs substantially about an outer perimeter of a wall  246  of the shear section  242 . The groove again constitutes an area of reduced material or reduced material thickness to promote breakaway.  
         [0041]      FIG. 14  is a cross-sectional view of another embodiment of the dual stop valve  330  in accordance with the present invention. The embodiment is the “dual butterfly valve assembly” embodiment. In this embodiment, the valve assembly  330  includes a first valve  338   a  and a second valve  238   b , both of the butterfly variety, again positioned within a disc  339  to form a disc assembly  340 . The principal of operation is similar to that described above in that both valves move simultaneously (or substantially simultaneously) from their closed position during transport and their open position during loading/unloading (shown in phantom), with a shear section  342  disposed between the valves. As illustrated, the shear section includes a notched groove  344  that runs substantially about an outer perimeter of a wall  346  of the shear section  342 . The groove again constitutes an area of reduced material or reduced material thickness to promote breakaway.  
         [0042]      FIG. 15  is a cross-sectional view of another embodiment of the dual closing valve in accordance with the present invention. The embodiment is referred to as the “Cam-butterfly valve assembly”. In this embodiment, the valve assembly  430  includes a first valve  438   a  and a second valve  438   b . Here, the first valve  438   a  includes a cam  448  that moves cam stem  450  which is connected to disc  452  to move and thereby compress spring  454 . The disc  452  compresses spring  454  within cage  456 . Here again, valve  438   a  includes seal  458  of an O-ring type. The generally principal of operation is similar to that described above in that both valves move simultaneously (or substantially simultaneously) from their closed position during transport and their open position during loading/unloading (shown in phantom), with a shear section  442  disposed between the valves. As illustrated, the shear section includes a notched groove  444  that runs substantially about an outer perimeter of a wall  446  of the shear section  442 . The groove again constitutes an area of reduced material or reduced material thickness to promote breakaway.  
         [0043]      FIG. 16  is a cross-sectional view of another embodiment of the dual stop valve assembly in accordance with the present invention. This embodiment can be referred to as a “Double Poppet Dry Break Valve Assembly”. In this embodiment, valve assembly  530  again includes a first valve  538  and a second valve  540 . As shown, the valves are poppet valves. Here, a cylinder  542 , or actuator, located within elbow portion  543  of assembly  530 , raises the lower valve  538 , which in turn contacts the upper valve  540  so as to elevate or drive the upper valve upperwardly. In one embodiment cylinder  542  is a hydraulic valve, and in another embodiment, the cylinder is a pneumatic cylinder. Upper valve  540  is connected to, as shown, a coil spring  544  which compresses as the upper valve moves upwardly. Here again, valve  538  includes seal  546  of an O-ring type. In general, the valves are in a closed position during transport and an open position during loading/unloading. Advantageously, there are no external linkages (i.e., linkages located external of the assembly housing or wall) connecting the valves, for again, the lower valve raises the upper valve. A break or shear section  548  is again disposed between the valves. As illustrated, the shear section includes a notched groove  550  that runs substantially about an outer perimeter of a wall  552  of the shear section  548 . The groove again constitutes an area of reduced material or reduced material thickness to promote breakaway. Advantageously, this “dry break design” results in very small amounts of material between the valves and a reduced amount of potential contamination during assembly breakage upon impact (and along the shear section). As a result, suitable applications or environments for the assembly  530  include chemical trailers.  
         [0044]     Also disclosed is a method of operating a dual stop valve assembly in a trailer having a flammable material stowing cargo tank and an external pipe for transporting a flammable material from the tank. The method comprises: attaching a dual stop valve assembly to a vehicle, the assembly including a pair of stop valves spaced and operable within an external pipe connection section, one of the pair of stop valves for sealing a flammable material within the cargo tank and the other of the pair of stop valves for sealing the flammable material within the external pipe. The method further comprises closing the first valve to isolate fluid communication within the tank and closing a second valve to isolate fluid communication within the outlet pipe. The external pipe connection section includes a break area for promoting breakage of the external pipe connection section along the break area such that, following the closing steps, and upon breakage along the break area, only an amount of flammable material that is stowed within the external pipe connection section and between the pair of stop valves is discharged. In at least one embodiment, the closing steps occur substantially simultaneously. In one embodiment, at least 2 actuators could be used.  
         [0045]     Despite any methods being outlined in a step-by-step sequence, the completion of acts or steps in a particular chronological order is not mandatory. Further, modification, rearrangement, combination, reordering, or the like, of acts or steps is contemplated and considered within the scope of the description and claims.  
         [0046]     While the present invention has been described in terms of a preferred embodiment(s), it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.