Patent Publication Number: US-6981513-B2

Title: Fluid flow management system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 09/628,075, entitled DRY BREAK VALVE ASSEMBLY, filed Jul. 28, 2000, now U.S. Pat. No. 6,672,327, and incorporated herein in its entirety by this reference. 

   BACKGROUND 
   1. Technological Field 
   The present invention relates generally to fluid systems. More particularly, embodiments of the present invention relate to a fluid flow management system that includes a dry break valve assembly which automatically terminates flow in the event constituent portions of the dry break valve assembly are separated for any reason. The fluid flow management system also includes a feedback system that, among other things, facilitates both the monitoring of the integrity of one or more joints of the dry break valve assembly, as well as the implementation of various actions corresponding to the data obtained as a result of such monitoring. 
   2. Related Technology 
   In recent years, environmental concerns have been receiving significantly more attention, and various governmental agencies have responded by implementing stringent regulations to reduce or prevent pollution. Many of these regulations and concerns are directed towards those industries that transport fluids. For example, it is very difficult to transport a fluid without spilling or leaking some of the fluid into the environment. Thus, some environmental regulations require that minimal leaking occur during handling, processing, or transportation of the fluid. 
   These environmental concerns become especially clear when considering the magnitude of the industries that handle hazardous fluids that, if allowed to escape even in relatively small quantities, can cause significant damage. There is a concern, therefore, to protect both the public and the environment from these types of fluids. While some fluids that are transported, such as water and milk, may not pollute the environment when they are leaked or spilled, the loss of fluid into the environment is nevertheless viewed as a general waste of resources. More generally, the loss of fluid into the environment is not desirable even if the fluid does not contribute to pollution. 
   Within the transportation industry, a variety of different devices are used to transport a fluid from a source to a destination. These devices often use valve assemblies and conduits of various types to both connect the source to the destination as well as to manage fluid flow through the conduit. Typically, the conduit is pressurized to direct fluid toward the desired destination. With each transfer of fluid, there is a risk that leakage will occur due to human error, equipment malfunctions, or the like. 
   A common source of fluid leaks and fluid spills are the valves and other components and devices employed in fluid systems. By way of example, some valves may have leaks that permit flow through the valve even when the valve is secured in the closed position. In other instances, one or more joints defined by constituent elements of the valve, such as in the case of valves designed to be taken down in two or more pieces, and/or one or more joints at least partially defined by the valve, such as a valve-to-flange connection, may be defective, resulting in leakage of some or all of the system fluid. Unfortunately, problems such as these often do not manifest themselves until after flow has been established through the valve, component, or device. 
   Thus, in many instances, the system operator is limited in terms of the affirmative steps that can be taken to prevent a spill that may result from one or more defective joints, and oftentimes can only correct the spill when it occurs. This is true in the case of joints that are defectively assembled, or are otherwise defective upon assembly, as well as in the case of joints that become defective over a period of time due to operating, or other, conditions. 
   Other problems exist as well. For example, various types of valves have been designed to stop, or “check,” fluid flow through the valve when the valve is taken down into two or more constituent parts or assemblies. One known device for checking fluid flow is a ball check valve. A ball check valve is essentially a ball which rests against a ball seat to form a valve. An operator may use the ball check valve to initiate or terminate the fluid flow. Despite the check feature of the ball check valve, a problem exists in the integrity of the fluid transfer system when the valve or conduit undergoes stress. 
   When the conduit and the valve are subjected to forces such as stretching, pulling, twisting, and the like, the fluid being transferred through the conduit and the valve may leak or spill into the environment. More particularly, the conduit, rather than the ball check valve, is likely to rupture or otherwise malfunction in the presence of these forces. Thus, while the ball check valve is appropriate for checking fluid flow, it does not prevent spillage or leakage when subjected to external stress. Because the conduit is likely to rupture, or otherwise malfunction, in these types of situations, the spillage or leakage of fluid into the environment can be significant because the fluid flow can no longer be checked. 
   For example, when a fuel transport vehicle is delivering liquid through a hose into a fuel tank, one end of the hose is attached to the fuel transport vehicle, and the other end of the hose is attached to a fuel tank. A valve such as a ball check valve may be disposed at the vehicle end of the hose such that fluid communication through the hose may be established or checked. 
   In the event the fuel transport vehicle drives away with the hose still connected, the connection will likely break or rupture. Because the hose is typically the weakest part of the connection, the break usually occurs somewhere in the hose and fluid escapes into the environment. In this example, the ball check valve typically does not disassemble because it is much stronger than the hose. Even if the ball check valve were to break instead of the hose, fluid would still leak from the system. Such problems are particularly acute in the context of automated environments and operations where few, or no, humans may be present, and a leak may go unnoticed for a relatively long period of time. 
   Accordingly, what is needed is a fluid flow management system having features directed to addressing the foregoing exemplary considerations, as well as other considerations not disclosed herein. An exemplary fluid flow management system includes a dry break valve assembly that automatically disassembles when excessive force is applied to the system to which the dry break valve assembly is connected. Moreover, the dry break valve assembly should be constructed to automatically terminate flow at substantially the same time as such disassembly occurs. Finally, the fluid flow management system should allow an operator to monitor the integrity of one or more of the dry break valve assembly joints, and to implement appropriate actions concerning the system in conjunction with which the fluid flow management system is employed, in the event such integrity is compromised. 
   BRIEF SUMMARY OF AN EXEMPLARY EMBODIMENT OF THE INVENTION 
   In general, embodiments of the invention are concerned with a fluid flow management system that, among other things, facilitates control of fluids before, during, and after transfer. 
   In one exemplary embodiment of the invention, a fluid flow management system is provided that includes a dry break valve assembly having first and second housing portions removably joined to each other and configured so that, when joined together, they collectively define a chamber. A flow control assembly is disposed in each of the first and second housing portions and each of the flow control assemblies are operably connected with an actuating mechanism which permits the simultaneous opening, and closing, of the flow control assemblies so as to permit, or prevent, respectively, flow through the dry break valve assembly. The dry break valve assembly is also configured so that upon separation of the first and second housing portions, the flow control assemblies each automatically assume a “closed” configuration, thereby preventing further fluid flow. 
   Additionally, the fluid flow management system includes a feedback system that among other things, facilitates both the monitoring of the integrity of one or more joints of the dry break valve assembly, as well as the implementation of various actions corresponding to the data obtained as a result of such monitoring. One exemplary embodiment of the feedback system includes a feedback system fluid source configured for communication with the chamber by way of a sensor line, as well as a pressure transducer in fluid communication with the sensor line, and a processor in electronic communication with the pressure transducer. 
   In this exemplary embodiment, the feedback system fluid source introduces fluid into the chamber and the pressure transducer until the chamber and pressure transducer are in static equilibrium with the feedback system fluid source. Because the chamber is formed proximate to the joint defined by the first and second housing portions, a relative movement between, or separation of, the first and second housing portions, will permit at least some of the pressurized feedback system fluid to escape. 
   In operation, a separation of the first and second housing portions causes the flow control assemblies to automatically assume the “closed” position, thereby preventing further fluid flow through the dry break valve assembly. At substantially the same time, separation of the first and second housing portions causes fluid to escape from the chamber, thereby upsetting the static equilibrium of the pressurized feedback system fluid. This disruption of the static equilibrium results in a pressure change that causes the pressure transducer to generate and transmit a corresponding signal which may then be employed to cause various actions to be taken respecting the system in conjunction with which the fluid flow management system is employed. In one exemplary embodiment, a processor in communication with the pressure transducer causes a visual and audible warning signal to be generated, indicating that the first and second housing portions have separated. 
   These and other, aspects of embodiments of the present invention will become more fully apparent from the following description and appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more particular description of various aspects of the embodiments of the invention illustrated in the appended drawings will now be rendered. Understanding that such drawings depict only exemplary embodiments of the invention, and are not therefore to be considered limiting of the scope of the invention in any way, various features of such exemplary embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
       FIG. 1  depicts an exemplary operating environment for at least some embodiments of the present invention; 
       FIG. 2  is a perspective view of an embodiment of the dry break valve assembly which includes a source housing and a destination housing that can be releasably connected to each other using a sleeve; 
       FIG. 3  depicts an embodiment of a sleeve which releasably seals and connects a source housing with a destination housing; 
       FIG. 4  is a perspective view indicating various details of a breakable link assembly that is an integral portion of a collar; 
       FIG. 5  is a perspective cutaway view of an embodiment of the present invention, illustrating various features of an actuating mechanism; 
       FIG. 6  is a cross section view of an exemplary sealing interface within an embodiment of a dry break valve assembly; 
       FIG. 7  is a perspective view illustrating various features of an exemplary embodiment of an actuating mechanism disposed within an embodiment of a dry break valve assembly; 
       FIG. 7A  is a side view illustrating various features of an embodiment of an actuating mechanism positioned so as to allow fluid flow through the dry break valve assembly; 
       FIG. 7B  is a side view illustrating various features of an embodiment of an actuating mechanism positioned so as to substantially prevent fluid flow through the dry break valve assembly; 
       FIG. 8  is a schematic view that illustrates various features of an embodiment of a feedback system; 
       FIG. 8A  is a schematic view of selected aspects of an alternative embodiment of the feedback system illustrated in  FIG. 8 ; 
       FIG. 8B  is a schematic view of selected aspects of another alternative embodiment of the feedback systems illustrated in  FIGS. 8 and 8A , respectively; 
       FIG. 9A  is a cutaway view of an embodiment of an exemplary fluid system component, specifically a dry break valve assembly, configured for use with a feedback system; 
       FIG. 9B  is a cutaway view of an alternative embodiment of an exemplary fluid system component, specifically a dry break valve assembly, configured for use with a feedback system; 
       FIG. 10  is a schematic view of an embodiment of a feedback system employed in conjunction with a control system; 
       FIG. 11  is a schematic view of an embodiment of a feedback system configured to generate line fluid leakage data; and 
       FIG. 12  is a schematic view of an alternative embodiment of a feedback system configured to generate line fluid leakage data. 
   

   DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION 
   Reference will now be made to figures wherein like structures will be provided with like reference designations. It is to be understood that the drawings are diagrammatic and schematic representations of various embodiments of the invention, and are not to be construed as limiting the present invention, nor are the drawings necessarily drawn to scale. 
   With reference first to  FIG. 1 , one embodiment of a fluid transfer system is indicated generally at  100 . Note that, as contemplated herein, “fluid” includes liquids, gases, liquid-gas combinations, slurries, liquid-solid combinations, gas-solid combinations, and liquid-solid-gas combinations. In the exemplary embodiment depicted in  FIG. 1 , fluid transfer system  100  includes a fluid source  102  configured for fluid communication with a dry break valve assembly  200 . Dry break valve assembly  200 , in turn, is configured for selective fluid communication with a fluid destination  104 , by way of a fluid conduit  106 . 
   As discussed elsewhere herein, it will be appreciated that dry break valve assembly  200  may be located, in its entirety, at fluid source  102 , or alternatively at fluid destination  104 . In one embodiment, discussed in detail below, dry break valve assembly  200  comprises at least two discrete portions, one of which may be located at fluid source  102 , and the other of which may be located at fluid conduit  106 , or vice versa in a fluid loading situation. 
   As contemplated herein, the term “conduit” is meant to include any structure or device adapted to facilitate transportation of a fluid, wherein such structures and devices include, but are not limited to, pipes, hoses, tubes, or the like. Fluid conduit  106  may be constructed of a variety of materials, or combinations thereof, including, but not limited to, metal, plastic, rubber, and the like. 
   With continuing reference to  FIG. 1 , the fluid source  102  is illustrated as a fluid transport vehicle, and the fluid destination  104  is illustrated as an underground tank. However it will be appreciated that fluid source  102  and/or fluid destination  104 , may comprise any of a variety of different static or mobile structures and vehicles. Such structures and vehicles include, but are not limited to, air, water, or land vehicles, such as, but not limited to, trucks, boats, automobiles, motorcycles, ships, railcars, aircraft, and the like, as well as structures such as tanks, reservoirs, and the like. 
   In operation, a pressure differential is established between fluid source  102  and fluid destination  104  so as to cause flow of the fluid through fluid conduit  106  in the desired direction. It will be appreciated that the pressure differential may be established in such a way as to cause flow to proceed in the opposite direction as well. The pressure differential may result from the force of gravity, or may alternatively be established by various types of equipment and devices including, but not limited to, pumps and the like. 
   In general, dry break valve assembly  200  facilitates management and control of fluid flow between fluid source  102  and fluid destination  104 . In particular, valve assembly  200  allows for selective establishment and termination of fluid communication between fluid source  102  and fluid destination  104 . Additionally, dry break valve assembly  200  facilitates releasable engagement of two different fluid system components, for example, fluid conduit  106  and fluid source  102 . Finally, dry break valve assembly  200  includes various features which substantially prevent fluid leakage should the discrete portions of dry break valve assembly  200  be separated for any reason. 
   With reference now to  FIG. 2 , dry break valve assembly  200  includes a first housing portion  202  and second housing portion  204 . As used herein, the portion of the valve assembly closest to the fluid source is referred to as the source housing while the other housing portion is referred to as the destination portion. Either portion of the dry break valve assembly can be the source housing or the destination housing. Coupling  500  serves to removably secure first housing portion  202  and second housing portion  204  in a substantially leakproof engagement. 
   Substantially disposed within first housing portion  202  and second housing portion  204 , respectively, are flow control assemblies  300 A and  300 B. In general, flow control assemblies  300 A and  300 B facilitate management of fluid flow through conduits, or the like, connected to first housing portion  202  and second housing portion  204 , respectively. Also disposed within first housing portion  202 , and discussed in greater detail below, is an actuating mechanism (not shown in  FIG. 2 ), which serves to manipulate the position of flow control assemblies  300 A and  300 B in response to input provided by way of actuating lever  402 . Thus, the position of the flow control assemblies  300 A and  300 B may vary between fully open and fully closed. 
   First housing portion  202  includes a conduit connector  202 A. Conduit connector  202 A is configured to attach to fluid conduit  106  (shown in  FIG. 1 ), wherein such attachment may be accomplished in a variety of ways including, but not limited to, welding, brazing, soldering, and the like. Alternatively, conduit connector  202 A may comprise a compression fitting, threaded fitting, or the like for attaching to fluid conduit  106 . 
   In similar fashion, second housing portion  204  has a conduit connector  204 A. Conduit connector  204 A is configured to attach to fluid conduit  106 , wherein such attachment may be accomplished in a variety of ways including, but not limited to, welding, brazing, soldering, and the like. Alternatively, conduit connector  204 A may comprise a compression fitting, threaded fitting, or the like for attaching to fluid conduit  106 . It will be appreciated that conduit connector  202 A and/or conduit connector  204 A may, alternatively, be connected directly to fluid source  102  or fluid destination  106 . 
   Directing attention now to  FIG. 3 , and with continuing attention to  FIG. 2 , additional details regarding coupling  500  are provided. As indicated in  FIG. 3 , coupling  500  includes a first engaging portion  500 A and a second engaging portion  500 B joined together by collar  502  which serves to substantially prevent relative motion between first engaging portion  500 A and a second engaging portion  500 B. Preferably, first engaging portion  500 A and a second engaging portion  500 B each comprise an outward extending annular ridge or the like which, when brought into a confronting relation with each other, are collectively configured to mate with corresponding structure defined by collar  502 , as suggested in  FIG. 3 . It will be appreciated however, that coupling  500  and collar  502 , either individually or collectively, may be configured in any number of alternate ways that would facilitate achievement of the functionality disclosed herein. In addition the connecting portions of the engaging portions  500 A and  500 B may be ridged to ensure that relative motion between the portions does not occur. 
   In one embodiment, first engaging portion  500 A and a second engaging portion  500 B each further includes a plurality of pins  504  that mate with corresponding grooves  202 B and  204 B, defined by first housing portion  202  and second housing portion  204 , respectively. Thus, a rotary motion imparted to coupling  500  by way of handles  506  releasably joins first engaging portion  500 A and a second engaging portion  500 B to first housing portion  202  and second housing portion  204 , respectively, by causing pins  504  to travel to the respective ends of grooves  202 B and  204 B. Preferably, grooves  202 B and  204 B are of such a length that a rotary motion of about 90 degrees is adequate to releasably couple first housing portion  202  to second housing portion  204 . It will be appreciated that a rotary motion of about 120 degrees in the opposite direction will be effective to disengage coupling  500  and thus release first housing portion  202  from second housing portion  204 . 
   It will be appreciated that the arrangement of coupling  500  with respect to first housing portion  202  and second housing portion  204  may be varied in a number of ways. For example, in one embodiment, first engaging portion  500 A is integral with first housing portion  202 , so that only second engaging portion  500 B comprises pins  504 . Correspondingly, only grooves  204 B are present and grooves  202 B are not required. In this embodiment, a rotation, preferably about 120 degrees, imparted to coupling  500  by way of handles  506  causes rotating pins  504 , or bearings in another embodiment, to travel the length of grooves  204 B so that coupling  500  thereby releasably joins first housing portion  202  to second housing portion  204 . 
   Yet another embodiment employs essentially a reverse configuration of that just discussed. In particular, in this embodiment, second engaging portion  500 B is integral with second housing portion  204 , and only first engaging portion  500 A includes pins  504 . Correspondingly, only grooves  202 B are present and grooves  204 B are not required. In this embodiment, a rotation, preferably about 90 degrees, imparted to coupling  500  by way of handles  506  causes pins  504  to travel the length of grooves  202 B so that coupling  500  thereby releasably joins first housing portion  202  to second housing portion  204 . 
   Finally, it will be appreciated that other types of structure and devices may be usefully employed to achieve the functionality collectively provided by pins  504  and grooves  202 B and  204 B. Accordingly, other structures and devices that provide such functionality are contemplated as being within the scope of the present invention, wherein such other structures and devices include, but are not limited to, threaded connections, spring-biased connections, and the like. 
   Directing attention now to  FIG. 4 , and with continuing attention to  FIG. 3 , additional details regarding collar  502  of coupling  500  are provided. In particular, collar  502  further includes a breakable link assembly  600 . Generally, breakable link assembly  600  serves two primary purposes. First, breakable link assembly  600  serves to retain collar  502  securely in place about first engaging portion  500 A and second engaging portion  500 B of collar  502 . Further, breakable link assembly  600  includes a sacrificial element that is designed to break, thereby allowing first engaging portion  500 A and second engaging portion  500 B to separate from each other, when a force, or forces, of predetermined magnitude are applied to particular elements of fluid transfer system  100 , such as to valve assembly  200 , or to fluid conduit  106 . 
   In effect, when the sacrificial element breaks, then the coupling  500  is no longer capable of joining the first and second housings of the valve assembly and the valve assembly disassembles into two separate components. As previously described, fluid flow from each separate housing may be checked and when the valve assembly separates in this manner, fluid flow is checked and fluid spillage or leakage is thereby minimized. 
   As suggested in  FIG. 4 , collar  502  is essentially C-shaped, having an opening between its two ends. Breakable link assembly  600  is disposed across the opening thus defined and includes a threaded member  602 , such as a bolt or the like, defining a bore (not shown) near one end. Preferably, the bore thus defined is substantially perpendicular to the longitudinal axis of threaded member  602 . A shear pin  604  is slidably disposed in the bore and the opposing ends of shear pin  604  are received in collar  502  as indicated. Preferably, shear pin  604  is prevented from exiting the bore by way of cotter pins  606 , or the like, disposed at either end of shear pin  604 . It will be appreciated that shear pin  604  may alternatively be glued, welded, brazed, or otherwise bonded to collar  502  so as to prevent it from exiting the bore in threaded member  602 . 
   Breakable link assembly  600  further includes a nut  608 , or the like, engaged for advancement along threaded member  602 . In operation, nut  608  is rotated so as to advance along threaded member  602  and thus draw the opposing ends of collar  502  securely together. 
   The operation of breakable link assembly  600  proceeds generally as follows. In the event a force, or forces, of predetermined magnitude in either a tensile or axial load are applied to valve assembly  200  and/or to fluid conduit  106 , shear pin  604  will fracture and the valve assembly will disassemble. It will be appreciated that the materials and/or geometry of shear pin  604  may desirably be varied to adjust the point at which fracture will occur. It will further be appreciated that sacrificial elements other than shear pin  604  may usefully be employed. In general, any sacrificial element and/or breakable link assembly that provides the functionality, disclosed herein, of shear pin  604  and/or breakable link assembly  600  is contemplated as being within the scope of the present invention. 
   Upon fracture of shear pin  604 , threaded member separates from collar  502 , thus permitting the ends of collar  502  to move apart and thereby allow separation of first housing portion  202  and second housing portion  204 . The functionality provided by breakable link assembly  600  thus ensures that in the event a predetermined level of force is applied to dry break valve assembly  200 , or to components to which it is connected, dry break valve assembly  200  will break dry, and thus substantially prevent any material leakage of fluid. Further, breakable link assembly  600  substantially ensures that in the event such forces are applied, no material damage occurs to the components of fluid transfer system  100  (see  FIG. 1 ). Thus, in addition to minimizing the fluid loss that would otherwise occur, the conduit  106  is preserved and damage is not done to the fluid source or the fluid destination. 
   Note that a variety of means may be profitably employed to perform the functions enumerated herein, of sealingly engaging first housing  204  with second housing  206  using coupler  500 . Coupler  500  is an example of means for sealingly engaging first housing portion  202  and second housing portion  204 . Accordingly, the structure disclosed herein simply represents one embodiment of structure capable of performing this function. It should be understood that this structure is presented solely by way of example and should not be construed as limiting the scope of the present invention in any way. 
   The valve assembly  200  and its various parts may be made of a range of materials depending on the type of fluid being transferred. Preferably, a material is chosen that can withstand corrosion and high temperature thermal cycling, such as carbon steel or stainless steel. Generally, valve assembly  200  may be constructed from Austenitic steel. 
     FIG. 5  shows an exploded perspective view of various features of the flow control assemblies of valve assembly  200 . The following description of the housing configuration and flow control assemblies is by illustration only and not by way of limitation. Generally, flow control assembly  300 A may comprise a flow control member  302 A, a guide  322 A, a resilient member  344 A, a fitting member  348 , and a snap ring  364 A. Similarly, flow control assembly  300 B may comprise a flow control member  302 B, a guide  322 B, a resilient member  344 B, a sealing member  350 , and a snap ring  364 B. 
   Flow control assemblies  300 A and  300 B have a flow control member  302 A and  302 B, respectively. As shown in  FIG. 3 , flow control members  302 A and  302 B have a round disc-like valve gate  304 A and  304 B, respectively. Valve gate  304 A contains a bore  320  substantially in the center of the valve gate so as to allow a substantially cylindrical piece to pass through the bore. It will be understood that bore  320  may be any geometrical shape (e.g., square, rectangular, polygonal, etc.) that will allow passage of a corresponding geometrical-shaped piece to pass through the bore. 
   Attached to valve gate  304 A is a hollow driver shaft  316 . Driver shaft  316  is placed in transverse relation to valve gate  304 B. Preferably, driver shaft  316  is substantially concentric with bore  320  and contains substantially the same geometric shape as bore  320 . Attached to valve gate  304 B is a member  318 , which may be solid or hollow. Driver shaft  316  and member  318  may be attached to valve gate  304 A and  304 B by any means known in the art, such as, but not limited to, welding, adhesive bonding, or may be formed integrally with valve gates  304 A and  304 B. 
     FIG. 5  further illustrates guides  322 A and  322 B. Guides  322 A and  322 B essentially add structural support to flow control assemblies  300 A and  300 B. Guides  322 A and  322 B contain bores  326 A and  326 B whose inner diameters correspond respectively with the outer diameters of driver shaft  316  and member  318 . In practice, driver shaft  316  slidably passes through bore  326 A, and, similarly, member  318  slidably passes through bore  326 B. Preferably, guides  322 A and  322 B are essentially hollow except for three support bars generally designated as  340 A and  340 B. The hollow structure allows for structural members to pass through guides  322 A and  322 B and to be movably connected to valve gates  304 A and  304 B, which will be discussed in further detail later in this specification. However, it will be appreciated that guides  322 A and  322 B may be constructed having a partially solid configuration as long as the requisite area is present to allow for movement of parts. 
     FIG. 5  shows resilient member  344 A and  344 B which are placed onto driver shaft  316  and solid member  318 , respectively. Resilient members  344 A and  344 B are shown in  FIG. 5  to be springs. However, one skilled in the art will understand that resilient members  344 A and  344 B may be any structure which maintains a bias such as, but not limited to, a rubber material, an elastic material, polished metal, and the like. 
     FIG. 5  further depicts fitting member  348  and corresponding sealing member  350 . The configuration of fitting member  348  and sealing member  350  will be discussed in more detail later in this specification. However, in general terms, fitting member  348  is tapered on one side to provide a valve seat for valve gate  302 A. Similarly, sealing member  350  is tapered on one side to provide a valve seat for valve gate  302 B. Preferably, valve gates  302 A and  302 B have corresponding tapers to allow for better sealing engagement. 
   As shown in  FIG. 2 , first housing portion  202  and second housing portion  204  are configured to allow for placement of flow control assemblies  300 A and  300 B to be disposed substantially within each housing.  FIG. 5  shows ridge  360  placed on the interior surface of first housing portion  202 . Ridge  360  acts as structural support for flow control assembly  300 A. During assembly, guide  322 A rests on ridge  360 . Resilient member  344 A is slid onto driver shaft  316 , after which flow control member  302 A is placed into first housing portion  202  with driver shaft  316  passing through bore  326 A. Finally, fitting member  348  is placed into first housing portion  202  to complete the flow control assembly  300 A. It will be understood from the drawings and foregoing discussion that flow control assembly  300 B may be assembled in a manner similar to that for flow control assembly  300 A. 
   It will be noted from  FIG. 5 , that second housing portion  204  has a ledge  362  to provide a similar structural function as ridge  360 . It will be appreciated that first housing portion  202  and second housing portion  204  may have structural ridges and grooves on the interior surface of the housing to provide for better structural engagement of corresponding parts of flow control assemblies  300 A and  300 B. 
   In one embodiment, snap rings  364 A and  364 B are provided for a better sealing engagement when flow control assembly  300 A and  300 B are assembled and for easier disassembly during maintenance of the valve assembly. In another embodiment, valve gate  304 A and  304 B may have an O-ring placed along the taper to provide for better sealing engagement. 
     FIG. 6  is a cross-section of an exemplary embodiment of the dry break valve assembly, illustrating the sealing engagement between first housing portion  202  and second housing portion  204 . First housing portion  202  and second housing portion  204  are joined in sealing engagement preferably in at least two ways—at their outer rims and between fitting member  348  and sealing member  350 . 
     FIG. 6  shows the outer rims of first housing portion  202  and second housing portion  204  in sealing engagement. During assembly of dry break valve assembly  200 , coupler  500  acts to join the outer rims of first housing portion  202  and second housing portion  204  to join them in sealing engagement. Tightening of the coupler  500  further acts to seal valve assembly  200 . Preferably, L-shaped grooves  204 B are configured such that sealing engagement occurs when pins  504  are engaged with L-shaped grooves  204 B. 
   Preferably, a sealing feature is also provided between fitting member  348  and sealing member  350 . As shown in  FIG. 6 , fitting member  348  is provided with a tapered ridge  368  running circumferentially around fitting member  348 . Similarly, sealing member  350  is provided with a corresponding tapered channel  370  running circumferentially around sealing member  350 . The terms “peripheral” and “circumferential” are adopted herewith to describe tapered ridge  368  and tapered channel  370  since tapered ridge  368  is disposed around the perimeter of an interior cavity formed within fitting member  348 . Thus, peripheral tapered ridge  368  peripherally defines the opening of a cavity formed through fitting member  350 . By providing ridge  368  and channel  370  with tapered surfaces, greater surface area is provided which allows an improved sealing engagement without increasing the diameter of the embodiment as is required, for example, to increase the sealing surface area when using a common flange joint. 
   Coupler  500  is provided with compressing edge  372  which biases compensating washer(s)  374  against abutting edge  376  of fitting member  348 . Coupler  500  attaches to the external surface of sealing member  350  by the twist coupling method discussed previously and described in more detail hereinafter. Compensating washer(s)  374 , shown best in  FIG. 6 , serves a dual purpose. Compensating washer(s)  374  provides compensation due to “creeping” (degradation of the seal due to thermal contraction) which occurs at low temperatures. Compensating washer(s)  374  also serves to bias coupler  500  in a direction which will hold pins  504  in the L-shaped grooves  204 B and thus provides the tension necessary for proper operation of the twist coupling. In this regard, when pins  504  are seated in the L-shaped grooves  204 B, compensating washer(s)  374  biases fitting member  348  towards sealing member  350 , and thus assists in forming a proper seal. 
   As can be seen best in  FIG. 6 , fitting member  348  is provided with an abutting edge  376  while coupler  500  is provided with a compressing edge  372 . One pin  504  and L-shaped groove  204 B can be seen in the lower portion of  FIG. 6 . Compensating washer(s)  374  is positioned so that compressing edge  372  and abutting edge  376  are urged apart. Pins  504 , grooves  204 B, and compensating washer(s)  374 , are arranged such that sealing contact between tapered ridge  368  and tapered channel  370  occurs when pins  504  are situated in grooves  204 B. This arrangement provides that when pins  504  are received in the grooves  204 B, compensating washer(s)  374  is partially or fully compressed. 
   It should be understood that compensating washer(s)  374  may be replaced by structures other than that shown and described in connection with  FIG. 6  above. For example, if the embodiment is to be used only under moderate temperature and pressure conditions, compensating washer(s)  374  may be a washer of a resilient or elastic material, such as rubber. Depending upon the application, those skilled in the art will be able to determine what alternative structures and materials may be used for compensating washer(s)  374 . The washer(s)  374  is preferably compressible so as to allow pins  504  to seat in grooves  204 B while urging tapered ridge  368  into sealing engagement with tapered channel  370 . This arrangement provides a coupling which is highly resistant to loosening due to vibration. 
   By the above-described arrangement, tapered ridge  368  is held in tight sealing arrangement with tapered channel  370 . Note that a variety of means may be profitably employed to perform the functions enumerated herein, of providing a sealing engagement between first housing portion  202  and second housing portion  204 . Fitting member  348  and sealing member  350  are examples of means for sealingly engaging first housing portion  202  and second housing portion  204 . Accordingly, the structure disclosed herein simply represents one embodiment of structure capable of performing these functions. It should be understood that this structure is presented solely by way of example and should not be construed as limiting the scope of the present invention in any way. 
   In one embodiment, an actuating mechanism is used to operate the flow control assemblies  300 A and  300 B.  FIG. 7  illustrates a perspective view of an actuating mechanism  501 . Preferably, actuating mechanism  501  uses cam action in operation. Cam action refers generally to a sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice versa. 
   As depicted in  FIG. 7 , actuating mechanism  501  has a cam handle  503 . Cam handle  503  provides three attachment sites,  512 ,  516 A, and  516 B. Attached to site  512  is cam arm  518 , which in turn is connected to driver  505  at attachment site  514 . Driver  505  has a first end  526  and a second end  528 . Driver  505  is shown in  FIG. 7  to be essentially cylindrical in shape. However, it will be understood that driver  505  may be any geometric shape which will correspond with driver shaft  316  and guide bore  326 A. Driver  505  is essentially a mechanical piece for imparting motion to components of the dry break valve assembly as will be discussed in further detail later in the specification. Attached to sites  516 A and  516 B are displacement shafts  506 A and  506 B. Displacement shafts  506 A and  506 B are shown in  FIG. 7  to be essentially rectangular in shape. However, it will be understood that displacement shafts  506 A and  506 B may be manufactured in any geometric shape, such as cylindrical, elliptical, square, and the like, without departing from the scope of the present invention. 
   Preferably the connections of driver  505  and displacement shafts  506 A and  506 B to cam handle  503  at sites  512 ,  516 A and  516 B are pin connections such that the parts may be movably connected. However, it will be understood that such connections may be done in a variety of ways known to the art including, but not limited to a bolt, a screw, pins, and the like. 
   As shown in  FIG. 2 , cam handle  402 , also referred to as an actuating lever, is connected to an actuating arm  510 , which, in turn, is connected to an actuating lever  508 . Actuating arm  510  is substantially disposed within first housing portion  202 . Actuating arm  510  is preferably placed such that it is substantially over the center of actuating mechanism  501 . Preferably actuating arm  510  and cam handle  503  are connected such that cam handle  503  cannot move independently of actuating arm  510 . 
     FIG. 7  also shows valve gates  304 A and  304 B in relation to actuating mechanism  501 . Valve gate  304 A is shown operably connected to actuating mechanism  501  while valve gate  304 B is disposed in operative relation to the actuating mechanism. Actuating mechanism  501  effects motion in both valve gate  304 A and  304 B at substantially the same time. 
   Valve gate  304 A is shown with second end  528  of driver  505  disposed through bore  320 . Preferably, in the resting position, second end  528  is substantially disposed within bore  320 . However, it will be understood that second end  528  may be partly out of bore  320  without departing from the scope of the present invention. The driver  505  is sized to slidably pass through bore  320  without substantial obstruction from bore  320 . 
   Displacement shafts  506 A and  506 B are shown to be connected to valve gate  304 A at attachment sites  520 A and  520 B. Bore  320  and sites  520 A and  520 B are placed in a triangular configuration with sites  520 A and  520 B being placed substantially equidistant from bore  320 . Sites  520 A and  520 B are also placed substantially equidistant from actuating arm  510  such that displacement shafts  506 A and  506 B are in substantial alignment with one another. Preferably the connections between displacement shafts  506 A and  506 B and connection sites  520 A and  520 B are pin connections such that the parts may be movably connected. However, it will be understood that the parts may be connected by known means in the art, such as, but not limited to, welding, bolting, and the like, without exceeding from scope of the present invention. 
   Referring now to  FIGS. 7A and 7B , the operation of actuating mechanism  501  will be discussed in detail.  FIG. 7A  shows a side view of actuating mechanism  501  at rest. Attachment site  512 , cam arm  518 , and attachment site  514  create a joint  530 . Generally, actuating mechanism  501  operates as follows: the operator depresses the actuating lever  402  (shown in  FIG. 2 ) and then the operator rotates actuating lever  402  which transmits a torque force (TF) through actuating arm  510  (not shown). The torque force (TF) is shown in  FIG. 7B  in the direction of the arrows. Such torque force (TF) rotates cam handle  503  which in turn rotates sites  512 ,  516 A, and  516 B (not shown). Thus, driver  505 , and displacement shafts  506 A and  506 B (not shown) will be in motion at substantially the same time. 
   As cam handle  503  rotates, site  512  rotates in a downward direction forcing motion through cam arm  518  and, in turn, forcing driver  505  in a downward direction. Driver  505  passes through bore  320  such that second end  528  of the driver comes into contact with valve gate  304 B. The downward motion of driver  505  pushes against valve gate  304 B, which displaces valve gate  304 B. The displacement of valve gate  304 B forces resilient member  344 B in a biased position. In one embodiment, located substantially at the center of valve gate  304 B is a groove  524 . The shape of groove  524  corresponds with the geometric shape of the end face of driver  505  such that driver  505  engages groove  524 . 
   At substantially the same time as site  512  is in motion, sites  516 A and  516 B are rotating in an upward direction, thus pulling displacement shafts  506 A and  506 B in an upward direction. This upward motion pulls at attachment sites  520 A and  520 B (not shown), which in turn pulls valve gate  304 A upward, displacing valve gate  304 A. The displacement of valve gate  304 A forces resilient member  344 A in a biased position. Thus, at substantially the same time, valve gates  304 A and  304 B are displaced or opened to establish fluid communication between the valve gates.  FIG. 7B  shows a side view of the actuating mechanism in full operation (i.e., fully opened) with valve gates  304 A and  304 B being displaced or opened. Thus, at least indirectly, actuating mechanism  501  acts to open both valve gates  304 A and  304 B at substantially the same time. 
   When actuating mechanism  501  is in fully open, with valve assembly  200  completely assembled, actuating mechanism  501  will lock into place automatically. This automatic locking feature is provided by the equilibrium of forces provided by the torque force (TF) and an equal and opposite retention force (RF) created by resilient member  344 B. During actuation, cam arm  518  acts to shift attachment site  512  from attachment site  514 , such that the sites are offset from one another as shown in  FIG. 7B . 
   In other words, when actuating mechanism  501  is completely actuated, joint  530  is in an overextended position. When actuating mechanism  501  is fully actuated, resilient member  344 B is depressed in a biased position. The retention force (RF) created by biased resilient member  344 B acts upwardly through valve gate  304 B to driver  505  to keep joint  530  locked in an overextended position. Once the retention force (RF) is applied, the torque force (TF) is no longer required and actuating mechanism  501  will remain locked until the retention force (RF) is removed. Thus, the present invention provides for an automatic locking mechanism when the actuating mechanism  501  is fully opened and dry break valve assembly  200  is fully assembled. 
   In one embodiment, dry break valve assembly  200  has an automatic check valve feature (i.e., fail closed feature). When the sealing engagement between first housing portion  202  and second housing portion  204  is broken, valve assembly  200  automatically closes to prevent substantial leakage of fluid. As discussed above, valve gates  304 A and  304 B are maintained in the open position by applying a torque force (TF) and/or a retention force (RF). When actuating mechanism  501  is fully activated, and the torque force (TF) is removed, actuating mechanism  501  remains locked due to the retention force (RF) as discussed above. Releasing the retention force (RF) will cause actuating mechanism  501  to automatically close. Essentially, if no torque force (TF) or retention force (RF) is applied, actuating mechanism  501  is predisposed to spring back into its original position because resilient members  344 A and  344 B are biased in the closed position, i.e., valve gates  304 A and  304 B close at substantially the same time. Release of the retention force (RF) may occur when first housing portion  202  is separated from sealing engagement with second housing portion  204 . It will be understood that separation of first housing portion  202  from second housing portion  204  may occur manually or automatically. Thus, the present invention provides for automatic checking of fluid flow whenever the valve assembly is disassembled, whether automatically or manually. 
   Directing attention now to  FIG. 8 , various details are provided regarding aspects of an alternative embodiment. In the exemplary embodiment illustrated in  FIG. 8 , a fluid system apparatus  700  is provided that comprises a dry break valve assembly  200  with associated coupling  500  (see, e.g.,  FIG. 7A ), and feedback system  800 . 
   In general, feedback system  800  comprises a feedback fluid source  802  arranged for fluid communication with a pressure transducer  804  or other suitable device, and with dry break valve assembly  200 , by way of a sensor line  806  which may comprise any type of pipe, conduit, or tubing suitable for the particular application or environment where fluid system apparatus  700  is to be employed, and which may be constructed of a variety of materials, or combinations thereof, including, but not limited to, metals, plastics, or rubber. Feedback system  800  further includes a processor  808  in communication with pressure transducer  804 , a memory  810  and display  812 . 
   In applications where volatile materials such as hydrocarbons may be present, it is desirable to locate devices such as pressure transducer  804 , which may produce sparks in some conditions, in an explosion-proof enclosure or other location where such hydrocarbons would be unlikely to come into contact with pressure transducer  804 . The same is likewise true with regard to any other components disclosed herein that could, under certain conditions, generate a spark. 
   As indicated above, both feedback fluid source  802  and pressure transducer  804  are arranged for fluid communication with dry break valve assembly  200 . Specific details concerning the interface between dry break valve assembly  200  and feedback system  800 , and their related operational features, are provided below in the context of the discussion of  FIGS. 9A and 9B . In general however, dry break valve assembly  200  includes two, or more, discreet portions (see  FIGS. 9A and 9B ) that, when joined together, cooperate to define a chamber  813  (see  FIGS. 9A and 9B ) capable of fluid communication, by way of sensor line  806 , with pressure transducer  804  and feedback fluid source  802 . In this exemplary embodiment then, the chamber  813  defined by dry break valve assembly  200  cooperates with feedback fluid source  802 , pressure transducer  804 , and sensor line  806  to collectively define the boundaries of a closed system having no outlet. In some embodiments, sealing devices including, but not limited to, gaskets and o-rings, comprising any suitable material(s), may be employed to facilitate formation and/or sealing of the chamber  813 . 
   In addition to the aforementioned components, at least some embodiments of fluid system apparatus  700  further include a plurality of isolation valves  814  that permit feedback fluid source  802 , pressure transducer  804 , and/or dry break valve assembly  200  to be isolated for maintenance or replacement. Isolation valves  814 , individually or collectively, may comprise gate valves, ball valves, globe valves, or any other device(s) that facilitate implementation of the functionality disclosed herein, and isolation valves  814  may comprise any material(s) compatible with the requirements of a particular application. Finally, various types of instrumentation including, but not limited to, pressure gauges and temperature gauges, may be included in fluid system apparatus  700  as appropriate. 
   Directing more specific attention now to feedback fluid source  802 , the volume of fluid provided by feedback fluid source  802  may comprise any fluid(s) consistent with the functionality disclosed herein, wherein such fluids may include, but are not limited to, liquids, gases, or combinations thereof. In one exemplary embodiment of the invention, the fluid provided by feedback fluid source  802  comprises a substantially inert gas, nitrogen for example. However, any other suitable gas or liquid, or combination thereof, may be employed as necessary to suit the requirements of a particular application. 
   Further, in at least some embodiments of the invention, feedback fluid source  802  also includes a check valve or similar device or feature which allows feedback fluid to flow out of feedback fluid source  802  to pressure transducer  804  and to the chamber defined by dry break valve assembly  200 , but does not allow fluid flow in the reverse direction. Feedback fluid source  802  may comprise a pump, compressor, or any other equipment capable of implementing the functionality disclosed herein. 
   Note that in one alternative embodiment, no feedback fluid source  802  is necessary. In this exemplary embodiment, a closed system is defined that is bounded by pressure transducer  804  or other suitable device, the chamber  813  defined by dry break valve assembly  200 , and sensor line  806 . A vacuum connection is provided in this closed system pump or any other equipment, system, or device capable of drawing a vacuum, generally referred to herein as “vacuum devices.” Pressure gages and/or other suitable instrumentation are employed to verify the existence and magnitude of the vacuum. Moreover, the vacuum may be defined with respect to any suitable reference point. In one embodiment of the invention, the vacuum is defined with respect to atmospheric pressure. 
   As suggested by the foregoing discussion, equipment and devices such as the feedback fluid source  802  and vacuum pumps disclosed herein are but exemplary structures that function as a means for exerting pressure, which may be either positive or negative with respect to a predetermined reference pressure. As disclosed herein, such means for exerting pressure generally serve to, among other things, establish and maintain a predetermined pressure in a substantially closed system. Accordingly, it should be understood that such structural configurations are presented herein solely by way of example and should not be construed as limiting the scope of the present invention in any way. Rather, any other structure or device that is effective in implementing the functionality disclosed herein may alternatively be employed. 
   With respect now to pressure transducer  804 , it was suggested earlier that a variety of means may be employed to implement the functionality of pressure transducer  804 . Thus, pressure transducer  804  is but an exemplary structure that functions as a means for sensing fluid flow. Accordingly, it should be understood that such structural configurations are presented herein solely by way of example and should not be construed as limiting the scope of the present invention in any way. Rather, any other structure or device that is effective in implementing the functionality disclosed herein may alternatively be employed. 
   By way of example, some embodiments of the invention may employ a flow switch instead of a pressure transducer. Such a configuration is illustrated in  FIG. 8A . As suggested by its name, flow switch  804 A would permit a determination to be made as to whether or not there was fluid flow through sensor line  806 . Since fluid flow can only occur in response to a pressure differential, such as would be detected by a pressure transducer, flow switch  804 A can be effectively substituted for pressure switch  804 . Note that the sensitivity, and/or other operational variables, of flow switch  804 A may be adjusted as necessary to suit the requirements of a particular application. 
   As another example, a differential pressure gauge  804 B may alternatively be employed in place of pressure transducer  804 , as indicated in  FIG. 8B . In such an arrangement, the high pressure side of differential pressure gauge  804 B is connected to sensor line  806  and the low pressure side of differential pressure gauge  804 B is exposed to atmospheric pressure. Any change in a predetermined pressure differential between the high pressure side (sensor line  806 ) and the low pressure side (atmospheric) of the differential pressure gauge, would serve to indicate that flow was occurring through sensor line  806 . 
   Other arrangements of differential pressure gauge  804 B that would be effective in implementing such functionality may alternatively be employed. For example, differential pressure gauge  804 B may be configured so that both the high and low pressure ports are in fluid communication with sensor line  806 . In a “no flow” condition, the differential pressure reading would be zero. In the event of flow through sensor line  806 , a non-zero differential pressure would be indicated at differential pressure gauge  804 B. As in the case of flow switch  804 A, the sensitivity, and/or other operational variables, of differential pressure gauge  804 B may be adjusted as necessary to suit the requirements of a particular application. Like pressure transducer  804 , flow switch  804 A and differential pressure gauge  804 B each comprise an exemplary structure that function as a means for sensing fluid flow. 
   Note that the exemplary flow switch and differential pressure gauge configurations illustrated in  FIGS. 8A and 8B , respectively, may each be employed using feedback fluid source  802 , or may alternatively be employed in a vacuum configuration, at least one embodiment of which is disclosed herein. 
   With continuing attention to  FIGS. 8 through 8B , and directing attention now to  FIG. 9A , details are provided concerning various aspects of the relation between feedback system  800  and dry break valve assembly  200  of fluid system apparatus  700 . As disclosed elsewhere herein and as indicated in the exemplary embodiment of dry break valve assembly  200  illustrated in  FIG. 9A , first housing portion  202  defines a tapered ridge  368  that is received within a tapered channel  370  defined by second housing portion  204  when first housing portion  202  and second housing portion  204  are joined together. 
   In the embodiment illustrated in  FIG. 9A , tapered ridge  368  and tapered channel  370  are configured so that when tapered ridge  368  is fully received within tapered channel, an annular gap, or chamber  813 , is defined by the bottom of tapered ridge  368 , and tapered channel  370 . Note however that the embodiment illustrated in  FIG. 9A  is exemplary only and variables including, but not limited to, the geometry and arrangement of tapered ridge  368 , tapered channel  370 , and chamber  813  may be modified or adjusted as necessary to suit the requirements of a particular application, equipment, or environment. 
   By way of example, components of dry break valve assembly  200  other than, or in addition to, first housing portion  202  and second housing portion  204 , may be employed to define chamber  813 . As another example, more than one chamber  813  may be defined, depending on the requirements of a particular application. As yet another example, it may be desirable in some embodiments to configure chamber  813  in such a way that it is in fluid communication with one or more portions of fluid passageway  201  defined by dry break valve assembly  200 . However, any configuration that facilitates implementation of the functionality disclosed herein may be employed. Accordingly, the scope of the invention should not be construed to be limited solely to the disclosed embodiments. 
   Directing continuing attention to  FIG. 9A , and with continued reference to  FIGS. 8 through 8B , further details are provided concerning the interface between dry break valve assembly  200  and feedback system  800 . As indicated in the exemplary embodiment illustrated in  FIG. 9A , a feedback port  204 C is defined that extends through second housing portion  204  and communicates with chamber  813 . One or more fitting(s), such as fitting  806 B, serve to facilitate connection of sensor line  806  to feedback port  204 C, and thereby enable fluid communication between sensor line  806  and chamber  813 . In one embodiment of the invention, fitting(s)  806 B comprise removable compression-type fittings. 
   In yet other embodiments, one or more of fittings  806 B may be permanently attached to sensor line  806  and/or second housing portion  204  to allow, for example, selective fluid communication between chamber  813  and feedback port  204 C. However, any other type of fittings and/or connection may be employed that are consistent with the functionality disclosed herein. Moreover, in the event the feedback port is defined in the housing portion of dry break valve assembly  200  that is attached to a mobile unit, such as a tanker truck, fittings  806 B, for example, permit a user to connect and disconnect feedback fluid source  802  with chamber  813  as/if required, as suggested above. 
   Similarly, various aspects of feedback port  204 C may be varied as necessary to suit the requirements of a particular application. For example, feedback port  204 C may be constructed so that it can be capped. As another example, feedback port  204 C may alternatively be defined by first housing portion  202 , as discussed below. Further, it may be desirable in some cases to employ multiple ports  204 C. Generally however, any configuration and/or arrangement of feedback port  204 C that facilitates implementation of the functionality disclosed herein may be employed. 
   Directing attention now to  FIG. 9B , aspects of an alternative embodiment of dry break valve assembly  200  and feedback system  800  are illustrated. Generally, the operational aspects of the embodiment illustrated in  FIG. 9B  are substantially the same as those of the embodiment illustrated in  FIG. 9A . Moreover, the embodiment illustrated in  FIG. 9B  is generally similar in other regards to the embodiment illustrated in  FIG. 9A  except that the feedback port, denoted at  202 C in  FIG. 9B , is defined in first housing portion  202  instead of being defined in second housing portion  204  ( FIG. 9A ). Such an arrangement may be desirable where, for example, second housing portion  204  comprises part of a fluid delivery system attached to a tanker truck and it would be impractical to provide a hard pipe connection between feedback fluid source  802 , located at a fluid transfer facility, and second housing portion  204 . 
   With continued attention to  FIGS. 8 through 9 , details are provided regarding various operational aspects of fluid system apparatus  700 , directing attention initially to an exemplary embodiment of feedback system  800 . Note in this regard that various alternative embodiments of feedback system  800  (aspects of which are illustrated in  FIGS. 11 and 12 ) are discussed below as they relate to, among other things, measurement of line fluid leakage from fluid system  1000  ( FIGS. 10 through 12 ). 
   With respect to the embodiment illustrated in  FIGS. 8 through 9 , at least, feedback system  800  serves to give an operator or other personnel some assurance as to the integrity of the joint cooperatively formed, for example, by first housing portion  202  and second housing portion  204  of dry break valve assembly  200 . Note however that, while feedback system  800  may be employed in conjunction with dry break valve assembly  200 , as in the case of fluid system apparatus  700 , such employment is exemplary only and feedback system  800  may, more generally, be employed in any application or environment where it is desired to obtain information, and/or implement one or more actions, concerning the integrity of one or more joints. 
   In operation, isolation valves  814  are opened, and feedback fluid source  802  transfers feedback fluid to the closed system bounded by feedback fluid source  802 , pressure transducer  804 , sensor line  806 , and chamber  813 , until such time as a predetermined pressure level is reached. The pressure of the feedback system fluid provided by feedback fluid source  802  may be selected as required based on the requirements of the particular application. As noted earlier, feedback fluid source  802  may not be required in all instances and, instead, a vacuum arrangement may be used in various embodiments of feedback system  800 . 
   After a predetermined pressure has been established, the closed system collectively defined by feedback fluid source  802 , pressure transducer  804 , sensor line  806 , and chamber  813 , will then be in a condition of static fluid equilibrium, that is, a condition where the pressure of the feedback system fluid is constant throughout the closed system and, accordingly, no pressure differential will be sensed by pressure transducer  804 . This static fluid pressure will be maintained, at least in part by feedback fluid source  802 , in the closed system so long as first housing portion  202  and second housing portion  204  are properly joined together. 
   Thus, a signal generated and transmitted by pressure transducer  804  under such static equilibrium conditions serves to indicate that, in the case of first housing portion  202  and second housing portion  204  for example, tapered ridge  368  of first housing portion  202  is fully received, and properly seated, within tapered channel  370  defined by second housing portion  204 . 
   Because first housing portion  202  and second housing portion  204  can be verified in this way to be properly joined together, a system operator can obtain a relatively high level of assurance as to the integrity of the joint formed by first housing portion  202  and second housing portion  204  and can, accordingly, transfer fluid through dry break valve assembly  200  with a relatively high level of confidence that no leaks will occur. Thus, it is a feature of at least some embodiments of the invention that a system operator can prospectively, and reliably, ensure the integrity of the joint(s) defined by dry break valve assembly  200 . This feature is particularly useful where, for example, dry break valve assembly  200  is to be used in conjunction with the processing of hazardous materials. 
   A related feature is that embodiments of the invention are effective in providing joint integrity feedback to the system operator during and after fluid processing operations, as well as beforehand. With specific reference to  FIGS. 9A and 9B , the integrity of the joint formed by first and second housing portions  202  and  204 , respectively, can be monitored without regard to whether valve gates  304 A and  304 B are in the “open” or “closed” position. As another example, in the event that a change occurs to the pressure of the feedback fluid during pumping operations, thus indicating a loss of joint integrity, a system operator may take appropriate remedial action concerning the system within which dry break valve assembly  200  is employed, such as, but not limited to, shutting down the pump. As discussed in greater detail below, such remedial actions may alternatively be performed automatically and substantially in real-time. 
   As suggested above, it is also a feature of embodiments of the invention that feedback system  800  can be configured to be quite sensitive, as even a slight misalignment or separation of first housing portion  202  and second housing portion  204  may permit feedback fluid to leak from chamber  813 , thereby triggering a feedback fluid pressure change that would be sensed by pressure transducer  804 . Such sensitivity is useful at least because such slight misalignments or separations would be unlikely to be identified during a simple visual inspection for example. Moreover, such sensitivity is desirable in those cases where hazardous materials are being processed and even very small spills are unacceptable. 
   Of course, in other applications, slight misalignments or other conditions may be permissible, and the sensitivity, and/or other pertinent operating parameters, of pressure transducer  804 , or other components of feedback system  800 , can be adjusted accordingly. It may also be desirable in some cases to adjust the sensitivity, and/or other pertinent operating parameters, of pressure transducer  804  to compensate for thermal expansion and/or contraction, and the attendant pressure changes, of the feedback fluid. 
   As noted above, static equilibrium in the closed system should be maintained so long as first housing portion  202  and second housing portion  204  are properly joined together and so long as there are no significant leaks elsewhere. However, in the event first housing portion  202  and second housing portion  204  are not properly joined together, or separate for some reason (thereby causing flow control assemblies  300 A and  300 B to automatically shut and prevent further flow through dry break valve assembly  200 ), some or all of the pressurized feedback system fluid will leak from chamber  813 , for example, past tapered ridge  368  and into fluid passageway  201 . Depending upon the nature of the defect in the joint formed by first housing portion  202  and second housing portion  204 , the feedback system fluid may additionally, or alternatively, escape from dry break valve assembly  200  into the surrounding environment. 
   It was noted earlier that fluid flow in this case implicates a change in pressure that will be sensed by pressure transducer  804 . Accordingly, pressure transducer  804  then generates and transmits a signal, which may be digital or analog, to processor  808 , that serves to signify that the integrity of the joint being monitored, in this case, the joint cooperatively defined by first housing portion  202  and second housing portion  204 , has been compromised in some way. As discussed below with reference to  FIG. 10 , this signal can then acted upon by processor  808  so as to enable appropriate action(s) to be taken concerning the system within which dry break valve assembly  200  is employed. 
   With continuing attention to  FIGS. 8 through 9 , further details are provided regarding the operational aspects of feedback system  800 . As noted earlier, feedback system  800  includes one or more processors  808  in communication with a memory  810  and display  812 . Note that processor  808 , memory  810 , and display  812  collectively comprise, in some embodiments, a computer or similar device, and that such computer or device may further comprise components such as, but not limited to, input devices such as keyboards, output devices, modems, and media readers and writers such as optical or magnetic disk drives. Further, such computer may be a portable device, and may be employed in a stand-alone configuration, or in conjunction with a computer network. 
   As discussed in further detail below, processor  808  is also configured for communication with, among other things, an equipment controller  902  ( FIG. 10 ). Communication between processor  808  and equipment controller  902 , as well as communication among the various components of feedback system  800 , and control system  900  ( FIG. 10 ), may comprise wireless communication, and/or hardwire-based communication. 
   In operation, one or more signals generated by pressure transducer  804  are transmitted to processor  808 . As described elsewhere herein, such signal(s) generally serve to indicate the status of the pressure in the closed system collectively defined by feedback system fluid source  802 , pressure transducer  804 , and chamber  813 , wherein such status may include, but is not limited to, static feedback fluid pressure, and a change in feedback fluid pressure. Note that, as disclosed herein, pressure transducer  804  may also be used to monitor, and generate and send corresponding signals relating to, a vacuum present in the closed system collectively defined by feedback system fluid source  802 , pressure transducer  804 , and chamber  813 . Finally, the signal(s) transmitted by pressure transducer  804  may be transmitted substantially continuously or on a predetermined intermittent basis. One or more pressure transducers  804  may be used to monitor a single joint, or multiple joints, depending upon the requirements of a particular application. 
   As suggested in  FIGS. 8 through 9 , the value, and/or other variables concerning the signal(s) produced by pressure transducer  804  or any other component in communication either directly or indirectly with processor  808 , may be stored in memory  810  so that a historical record of data concerning the integrity of the joint formed in dry break valve assembly  200 , and/or any other joint(s) of interest whether or not such joints are defined either in whole or in part by dry break valve assembly  200 , may be created and preserved. Examples of data types that may be gathered and/or stored include, but are not limited to, the pressure of the feedback fluid, the time at which such pressure was measured, the magnitude of the change in pressure of the feedback fluid, and the time at which such change in pressure occurred. 
   As further suggested in  FIGS. 8 through 9 , one or more aspects of the signal(s) produced by pressure transducer  804  and transmitted to processor  808  may be presented on display  812  in a form and manner consistent with the particular application with which feedback system  800  is employed. By way of example, the magnitude of the pressure of the feedback fluid as a function of time may be plotted and displayed. 
   Moreover, a variety of means may be employed to perform the functions of feedback system  800 . Thus, the embodiments of feedback system  800  disclosed herein are but exemplary structures that function as a means for monitoring joint integrity. Accordingly, it should be understood that the structural configurations of feedback system  800  disclosed herein are presented solely by way of example and should not be construed as limiting the scope of the present invention in any way. Rather, any other structure, feature, or combination thereof, that is effective in implementing the functionality of feedback system  800  may alternatively be employed. By way of example, and as suggested above, some embodiments of the present invention are directed to a feedback system  800  that includes a flow switch  804 A, or differential pressure gauge  804 B, in place of pressure transducer  804 . 
   Note that while at least one embodiment of feedback system  800  may be employed in conjunction with dry break valve assembly  200 , the scope of the invention should not be construed to be limited solely to that application. In fact, feedback system  800  may be employed in conjunction with any fluid system component which includes discrete elements that cooperate to form a joint whose integrity is of interest or concern. Accordingly, embodiments of feedback system  800  may be employed in conjunction with fluid system components such as, but not limited to, a pair of pipe flanges that, when joined together, form a joint and associated chamber. Alternatively, feedback system  800  may be employed in conjunction with a joint formed by two distinct fluid system components, such as the joint formed by a valve flange and a tank flange. The foregoing are exemplary only however, and the scope of the present invention should not be construed to be limited to any particular arrangement of one or more fluid system components. In fact, as discussed below, the scope of the present invention is not limited to fluid systems. 
   Specifically, the joint(s) to be monitored need not be concerned at all with the fluid systems, and may, in fact, comprise any joint whose integrity is of interest or concern. By way of example, a joint in a machine may be designed so as to form a chamber when two discrete elements of the machine are fastened together. Moreover, the chamber need not necessarily be defined by the joint. Instead, any chamber that is configured such that a pressure change in the chamber corresponds in some manner to a loss of joint integrity may be employed. Note that while, in the case of devices such as dry break valve assembly  200 , where the chamber is substantially defined solely by the device itself, other configurations and devices may be employed wherein the chamber is only partially defined by the device, and wherein additional structures or devices are employed to more completely define the chamber. 
   As the foregoing example suggests, embodiments of feedback system  800  may be employed with any device having two or more discrete elements that cooperate to form a joint. Note that, as contemplated herein, “device” may comprise either a single structure or multiple structures, and the “discrete elements” of such device may refer to separate portions of a single structure that comprises the device, or may alternatively refer to separate structures that collectively comprise the device. 
   In view of the foregoing, feedback system  800  may be employed with any joint and chamber configuration, without being limited to a specific manner or structure concerning the formation and/or configuration of such joint and/or chamber. Accordingly, embodiments of the invention should not be construed to be limited to any particular structural configuration or arrangement. 
   With continuing attention now to  FIGS. 8 through 9 , and directing attention now to  FIGS. 10 through 12 , details are provided concerning various aspects of an exemplary embodiment of a control system  900 . As indicated in those figures, control system  900  includes one or more equipment controllers  902  in communication with processor  808 . One feature of such an arrangement is that the signal(s) produced by, for example, pressure transducer  804 , can be used to implement various actions with respect to fluid flow through dry break valve assembly  200  or, more generally, the fluid system  1000  within which dry break valve assembly  200  is employed. 
   In the illustrated embodiment, the signal(s) received by processor  808  from pressure transducer  804  causes processor  808  to generate one or more appropriate sets of instructions which are then transmitted to equipment controller  902 . In response, equipment controller  902  generates a corresponding control signal which is then used to implement, by way of equipment  904  including, but not limited to, pumps, valves, and other equipment, one or more particular actions with respect to fluid system  1000 . 
   The response of fluid system  1000  is returned to equipment controller  902  in the form of a feedback signal. By comparing the feedback signal with the instructions received from processor  808 , equipment controller  902 , if necessary, generates another control signal so as to cause the associated equipment  904  to adjust, for example, the performance or operational characteristics of fluid system  1000 . Thus, the integrity, or lack thereof of the joint defined either in whole or in part by dry break valve assembly  200 , or by any other component or device to be monitored, can be used to cause various actions or omissions of action, as applicable, with respect to the system within which such component or device is employed. In other embodiments, the control signal generation and comparison is performed by processor  808 . 
   Note that, as contemplated herein, “equipment controller” refers to any circuits, systems, and/or devices that use input from feedback system  800  and from equipment  904  to regulate or manage any aspect of the performance or operation of fluid system  1000 . Consistent with the foregoing, at least one embodiment of the invention, discussed below, includes an equipment controller  902  that comprises a start/stop controller of a fluid pump. 
   Specifically, in one exemplary embodiment of control system  900 , pressure transducer  804  is interlocked with an equipment controller  902  that comprises a start/stop controller of a fluid pump which is in fluid communication with dry break valve assembly  200 . One feature of such an exemplary arrangement is that in the event pressure transducer  804  generates, and transmits to processor  808 , a signal indicating a loss of integrity in the monitored joint, processor  808  will then generate and send appropriate instructions to the start/stop controller associated with the fluid pump, thereby preventing startup of the fluid pump and thus, preventing leakage from dry break valve assembly  200 . A related feature is that such an arrangement affords substantially real-time control of fluid system  1000  within which the fluid pump and dry break valve assembly  200  are employed. The real time control feature is also germane to those embodiments wherein feedback system  800  and/or control system  900  is employed with other than fluid systems. 
   Control system  900  is not, however, limited solely to the foregoing exemplary functionality. In other embodiments of the invention, control system  900  may be employed to reduce the pressure of the flow through dry break valve assembly  200  to a level that would substantially foreclose, or at least reduce, leakage, even in the event that integrity of the joint is lost, and/or control system  900  may be used to vary the flow rate or other variables of the flow associated with dry break valve assembly  200 . 
   In general, embodiments of control system  900  may be employed to, among other things, cause the performance of various actions corresponding to a particular state of joint integrity. Accordingly, embodiments of the invention should not be construed to limited solely to the exemplary functionalities or features disclosed herein. Moreover, embodiments of control system  900  are not limited solely to fluid systems applications but, more generally, may be employed in the context of any system where it is desired to monitor the integrity of one or more joints and/or cause the implementation of one or more actions, corresponding to various states of joint integrity, concerning the system or device within which the monitored joint(s) are present. Finally, embodiments of control system  900  may be combined with embodiments of feedback system  800  to form a fluid management and control system  1100 . 
   With more specific attention now to  FIGS. 11 and 12 , details are provided concerning various aspects of alternative embodiments of feedback system  800 . Specifically, some embodiments of the invention may include provisions for using the signal(s) generated by pressure transducer  804  (see, e.g.,  FIG. 10 ), or other equipment or devices, to generate quantitative data concerning any leakage that may occur, for example, from chamber  813  of dry break valve assembly  200 . As an example, in the event leakage is occurring from chamber  813 , pressure differential data gathered by pressure transducer  804  over a period of time can be transmitted to processor  808  and used to determine, among other things, the rate at which such leakage is occurring, as well as the specific amount of feedback system fluid that is lost, and/or the amount of line fluid that is lost from fluid system  1000 , wherein “line fluid” refers to the fluid or material passing through and/or processed by way of, fluid system  1000 , as distinct from the feedback system fluid discussed elsewhere herein. As discussed below, the ability to make such determinations may prove useful in some applications. 
   At least in cases where the feedback system fluid comprises a compressible fluid, conservation of mass principles for compressible fluids can be used to derive the rate at which feedback system fluid is leaking from chamber  813 . Such principles can also be employed in conjunction with those embodiments where a vacuum arrangement is employed in the place of a feedback system fluid because, in the event of a loss of joint integrity, a flow of atmospheric air, a compressible fluid, into the chamber  813  will occur. 
   The following gas dynamics equations may be used in conjunction with the determination of mass flow rates of compressible fluids (note that it is implicit in Equations 1 and 2 below that the feedback system fluid or atmospheric air, as applicable, acts as a perfect gas and that any flow of the feedback system fluid is substantially frictionless):
 
 V ×(∂ ρ/∂t )− m= 0=&gt; m=V ×(∂ρ/∂ t )  Equation 1
 
∂ρ/∂ t =(∂ρ/∂ t )/ RT=&gt;m=V ×((∂ρ/∂ t )/ RT )  Equation 2
         where:
           V=volume of space containing the feedback system fluid (known)   m=mass flow rate (to be calculated)   R=feedback system fluid constant (given)   T=feedback system fluid temperature (measured)   p=pressure of the feedback system fluid (measured)   t=time (measured)   ∂p/θt=rate of pressure change (measured)   ρ=feedback system fluid density (known)   ∂ρ/∂t=rate of feedback system fluid density change (calculated)   
               

   In this exemplary embodiment, the volume V can be readily determined by metering the amount of feedback system fluid that is introduced by feedback fluid source  802  (or removed by a vacuum device, as applicable) into the closed system collectively defined, for example, by feedback fluid source  802 , thermometer  816 , pressure gauge  818 , sensor line  806 , and chamber  813 . Moreover, the gas constant R for nitrogen, for example, is 0.2968 kJ/kg×K and can be easily obtained from a gas table, and the temperature T of the feedback system fluid is readily ascertained by way of a thermometer  816  ( FIG. 11 ) in fluid communication with sensor line  806 . In the illustrated embodiment, thermometer  816  is configured to transmit feedback system fluid temperature data to processor  808 . Similarly, pressure gauge  818  is arranged for fluid communication with sensor line  806  and is configured to transmit feedback system fluid pressure data to processor  808 . 
   By receiving, on a substantially continual basis, or other desirable time basis, the feedback system fluid temperature T data from thermometer  816  and feedback system fluid pressure p data from pressure gauge  818 , correlating at least the feedback system fluid pressure data to time t, and by combining such data with the known values of V and R, in the manner suggested by Equations 1 and 2, processor  808  is able to use an algorithm embodying Equations 1 and 2 to calculate, on a real-time basis, the mass flow rate m, if any, of the feedback system fluid out of chamber  813 . 
   Note that because the presence of pressure gauge  818  permits the value of pressure p to be measured, on a continual or other basis, as a function of time t, the pressure differentials, as well as changes in pressure with respect to time, can be readily calculated by processor  808 , thereby obviating the need, at least in the exemplary embodiment illustrated in  FIG. 11 , for pressure transducer  804 . It may be desirable in other cases however, to employ both pressure transducer  804 , or other equipment, and pressure gauge  818 . 
   Further, because feedback system  800  is able gather and process feedback system fluid temperature data, some embodiments of feedback system  800  are configured to compensate for changes in the pressure of the feedback system fluid that result from conditions other than a loss of joint integrity. As an example, a decrease in ambient temperature would likely cause the pressure of the feedback system fluid to drop, thereby resulting in generation of a pressure drop signal that could erroneously be interpreted to indicate a loss of joint integrity. 
   Moreover, the ability of feedback system  800  to monitor and collect various types of feedback system fluid data on an ongoing basis permits feedback system  800  to interact with control system  900  and respond in a desired manner to various predefined feedback system fluid conditions, such as by facilitating the implementation of appropriate corresponding actions, disclosed elsewhere herein, concerning fluid system  1000 . By way of example, embodiments of feedback system  800  can be configured to monitor the feedback system fluid for the presence or occurrence of various conditions such as, but not limited to, a predetermined rate of pressure drop, a pressure drop of predetermined magnitude, and the occurrence of any change in pressure. 
   Similar to the case of other exemplary embodiments disclosed herein, the data collected by feedback system  800  through the use of thermometer  816  and pressure gauge  818  may be stored in memory  810 , presented on display  812 , and/or processed in various ways by processor  808 . As discussed herein, processor  808  serves to calculate, among other things, pressure differentials and changes in pressure with respect to time, or any other parameters that can be derived from known and/or measured data and information. 
   As noted elsewhere herein, a flow of feedback system fluid usually indicates that the integrity of the associated joint has been compromised in some way, or that the joint was improperly formed in the first instance. In the event such a compromise occurs, the line fluid present in fluid passage  201  (see, e.g.,  FIGS. 9A and 9B ) of dry break valve assembly  200 , for example, will in many cases tend to flow into chamber  813  at substantially the same rate at which the feedback system fluid flows out of chamber  813 . Thus, the leak rate of the line fluid can be closely approximated, in real time, by determining the mass flow rate m of the feedback system fluid which, as discussed above, can be readily performed with various embodiments of the invention. 
   The ability to determine, in real time and on a continual basis, the leak rate, if any, of the line fluid is useful in a number of applications. By way of example, in some hydrocarbon processing evolutions, specific parts per million (ppm) figures for permissible line fluid discharge have been established by various regulatory bodies, and failure of the processing plant operator to conform with such standards may result in substantial fines and/or plant shutdown. Thus, this exemplary embodiment of feedback system  800  serves not only to provide feedback to the processing plant operator concerning joint integrity, and to facilitate implementation of corresponding remedial actions if required, but also to enhance the ability of the processing plant operator to verify and maintain compliance with relevant operational standards through the monitoring and determination of line fluid leak rates. Note that in at least one embodiment, flow switch  804 A ( FIG. 8A ) may be configured to generate an alarm signal in the event the line fluid leak rate exceeds a predetermined value. Further, feedback system  800  may be readily reconfigured or adjusted as required for consistency with changes in permissible discharge ppm, or other, standards. 
   In the exemplary embodiment of feedback system  800  illustrated in  FIG. 11 , mass flow rates m of the feedback system fluid are derived at least in part through the use of feedback system fluid pressure data supplied by a pressure gauge or similar device. However, it may be desirable in some cases to measure such mass flow rates m directly. Various features of an exemplary embodiment of a feedback system  800  configured in this way are illustrated in  FIG. 12 . 
   As indicated in  FIG. 12 , the illustrated embodiment of feedback system  800  includes a flow meter  820 , in fluid communication with sensor line  806 , that permits direct measurement of mass flow rates m. Further, flow meter  820  is in electronic communication with processor  808  so that signals generated and transmitted by flow meter  820  can be received and processed by processor  808  generally as disclosed elsewhere herein. In some cases, processor  808  causes the storage, manipulation, and/or display of data received by processor  808  from flow meter  820 . As another example, processor  808  may use data received from flow meter  820  to facilitate the implementation of various actions, such as by way of various equipment controllers, concerning the fluid system  1000  in conjunction with which feedback system  800  is employed. 
   The specific type, and/or operational characteristics, of flow meter  820  employed in a given application may be selected depending on upon various factors, such as whether the feedback system fluid comprises a gas or a liquid. Exemplary types of flow meters that may be employed include, but are not limited to, thermal mass flow meters, and induction-based flow meters. In general however, any type of flow meter or other device useful in implementing the functionality disclosed herein may be employed, and the scope of the present invention should not be construed to be limited to any particular type of flow meter. 
   Further, the operational characteristics of the flow meter may likewise be selected and/or adjusted based upon particular application requirements. By way of example, the flow meter may be configured to store a predetermined number of real time data points that can be transmitted to a processor such as processor  808 , for example. Further, the flow meter may be configured to measure, in addition to flow rate at a particular point in time, the total volume of flow that has occurred through the flow meter over a given period of time. Moreover, the flow meter can be set to generate an alarm or other signal under various specified conditions concerning the feedback system fluid and/or line fluid wherein such conditions include, but are not limited to, passage of a predetermined volume of flow, passage of a predetermined volume of flow over a defined time interval, or upon the occurrence of any flow. 
   As suggested by the discussion herein concerning the determination of mass flow rates m, and various other characteristics, of the feedback system fluid, various approaches may be utilized in making such determinations. In particular, a computational approach, as exemplified by the use of pressure data, and gas dynamics conservation of mass principles and equations, examples of which are disclosed herein, may be desirable in some cases. In other cases however, an empirical approach may be desirable. In at least one embodiment disclosed herein, such an empirical approach is exemplified by the use of devices and instruments such as flow meters to directly measure the mass flow rate m of the feedback system fluid. In view of the foregoing, the scope of the invention should not be construed to be limited solely to a particular computational or empirical technique, or to a particular type of technique. Rather, any technique or approach, or combination thereof, useful in implementing the functionality disclosed herein may be employed. 
   It should be noted that equipment and devices such as the pressure gauge  818  and flow meter  820  disclosed herein are but exemplary structures that function as a means for producing line fluid leakage rate data. As disclosed herein, such means for producing line fluid leakage rate data serve to, among other things, measure a line fluid leakage rate directly, as in the case of flow meter  820 , or generate data, such as feedback system fluid pressure data for example, that can be used to derive the line fluid leakage rate, as in the case of pressure gauge  818 . Accordingly, it should be understood that such structural configurations are presented herein solely by way of example and should not be construed as limiting the scope of the present invention in any way. Rather, any other structure or device that is effective in implementing the functionality disclosed herein may alternatively be employed. 
   The described embodiments are to be considered in all respects only as exemplary and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.