Abstract:
A pneumatically controlled assembly, system, method and device for the regulation of pressure of a gas as it flows in a pressurized line and including at least one loading valve which is set to respond to variations in pressure in conjunction with a pneumatically actuated process control valve so as to effectively regulate and maintain pressure of the gas in the pressurized line.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a divisional of of U.S. application Ser. No. 13/899,013, filed May 21, 2013, which claims priority to U.S. Provisional Application No. 61/649,460 titled “Gas Line Control System” and filed on May 21, 2012 as well as U.S. Provisional Application No. 61/825,408 titled “Gas Line Control System” and filed on May 20, 2013. The &#39;013, &#39;460 and &#39;408 provisional applications are incorporated herein by reference. 
         [0002]    Further, U.S. Pat. No. 5,762,102 to Rimboym, titled “Pneumatically Controlled No-Bleed Valve And Variable Pressure Regulator” issued to Becker Precision Equipment, Inc. on Jun. 9, 1998, is also incorporated herein by reference. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0003]    The present device relates to devices and systems for regulation and control of pressure in pressurized gas delivery lines. Particularly, the present device and system relate to a variable pressure controller (VPC) for regulation and control of fluid flow in a delivery line. 
       BACKGROUND OF THE INVENTION 
       [0004]    Pressure regulators equipped with variable pressure regulator pilot valves are used as operating regulators, monitors, stand-by regulators and relief valves. Prior to the invention of U.S. Pat. No. 5,762,102, such valves were designed to maintain the desired pressure of fluid in a delivery line by operating with a constant “bleed” from the valve. This was not only wasteful but, in the case of some fluids, was environmentally undesirable. Environmental costs and problems are caused by discharge of pollutants to the air. Bleed gas from natural gas pipelines to the atmosphere year after year only adds to the growing environmental problem. Overall, industry estimates place the discharge of natural gas to the atmosphere from a single controller operating with constant bleed to the atmosphere, in excess of 300,000 standard cubic feet (SCF) per year. 
         [0005]    In the present invention, while the no-bleed controller is of import, embodiments of the present invention address problems with the following key features: 
         [0006]    VPC with one common block and external manifolds; 
         [0007]    VPC with two different internal loading valves; 
         [0008]    VPC with Manual Operation Valve (Rotary Type)—attached via manifold configuration; 
         [0009]    VPC with external insertion of Nozzle Assembly; 
         [0010]    VPC-PID with variable gain; 
         [0011]    System configurations above adaptable to diaphragm style rotary pneumatic positioner via addition of proportional feedback mechanism; 
         [0012]    Double-acting, single-acting (reverse) and single-acting (direct) in one common VPC configuration; 
         [0013]    VPC with conditioning of output and exhaust flow paths via manifolds; 
         [0014]    Interchangeability of “normally open” and “normally closed” internal loading valves in same body; and 
         [0015]    Coupling of the “derivative” adjustable orifice on output of “ID” models—derivative adjustment is configured in manifold system and also incorporates “flow conditioning.” 
         [0016]    These and other problems are solved by the present VPC device and system. 
       SUMMARY OF THE INVENTION 
       [0017]    The following presents a simplified summary of embodiments of the system and method of the disclosed invention. The summary is intended to introduce particular useful elements, which may be critical to a particular embodiment and optional for other embodiments. Though not specifically summarized here, other critical and optional elements, including combinations of such elements, may also be possible. 
         [0018]    Generally speaking, a pneumatic valve pressure controller system having a fluid supply line and a variable pressure controller coupled to a process process control valve within the supply line, is described. 
         [0019]    In a particular embodiment, a supply regulator is fluidly coupled to the fluid supply line upstream of the process process control valve and an actuator is operably connected to the process process control valve, the actuator having a first pressure chamber and a second pressure chamber. A sensing diaphragm connected to the fluid supply line determines a relative pressure in the fluid supply line on the outlet end side of the process process control valve, while a first loading valve is fluidly coupled to the first pressure chamber and responsive to the sensing diaphragm and a second loading valve is fluidly coupled to the second pressure chamber and responsive to the sensing diaphragm. In such an embodiment, the first loading valve and the second loading valve open and close in response to the sensing diaphragm to change a position of the actuator and thereby operate the process process control valve. 
         [0020]    In specific embodiments, the first loading valve and the second loading valve are of a normally closed configuration. Accordingly, the first loading valve and the second loading valve may move between a closed position and an open position independent of one another or they may move synchronously between a closed position and an open position. In the first instance, a pressure rise in the fluid supply line determined by the sensing diaphragm opens the first loading valve which changes the position of the actuator to move the process process control valve toward a fully closed position, while a pressure drop in the fluid supply line determined by the sensing diaphragm opens the second loading valve which changes the position of the actuator to move the process process control valve toward a fully open position. In the latter instance, a pressure threshold in the fluid supply line determined by the sensing diaphragm opens the normally closed first and second loading valves, which changes the position of the actuator to operate the process process control valve toward a position to adjust fluid flow. 
         [0021]    In further specific embodiments, the system of further comprises a first adjustable orifice fluidly in-line with the first loading valve and a second adjustable orifice fluidly in-line with the second loading valve, the supply regulator and the first adjustable orifice. 
         [0022]    In alternate embodiments, the first loading valve and the second loading valve are of a normally open configuration. 
         [0023]    Further, in an embodiment of the method for controlling a fluid supply through a delivery line having a process process control valve therein to maintain a supply side pressure and a delivery side pressure, and a pneumatic actuator having a first pressure chamber and a second pressure chamber and used to operate the process process control valve, the steps include setting a delivery side target pressure range for the fluid supply, sensing the delivery side pressure, and operating the pneumatic actuator to either maintain the actuator in a static state when the delivery side pressure is within the target range or move the actuator to adjust the process process control valve position when the delivery side pressure is outside the target range. 
         [0024]    In a specific embodiment of the method, the first and second pressure chambers of the actuator are responsive to a first loading valve fluidly coupled to the first pressure chamber and a second loading valve fluidly coupled to the second pressure chamber, and the first loading valve and the second loading valve open and close in response to the delivery side pressure to change a position of the actuator and thereby modulate the position of the process process control valve. 
         [0025]    Further, a variable pressure controller is also described and claimed. Generally speaking, the controller is comprised of a first fluid interface for coupling to a fluid line upstream of a process process control valve, a sensing mechanism positioned at the first fluid interface and responsive to a pressure in the fluid line upstream of a process process control valve, a first loading valve responsive to the sensing mechanism, a second loading valve responsive to the sensing mechanism, a first manifold comprised of two outlet ports, wherein one outlet port is coupled to a first channel fluidly coupled to the first loading valve and one outlet port is coupled to a second channel fluidly coupled to the second loading valve, and a second manifold comprised of two outlet ports, wherein one outlet port is coupled to a first channel fluidly coupled to the first loading valve and one outlet port coupled to a second channel fluidly coupled to the second loading valve. 
         [0026]    In a specific embodiment of the VPC, at least one module capable of interfacing with at least one of the first manifold and the second manifold. Additionally, the first loading valve and the second loading valve may be one of either a “normally closed” or “normally open” valve configuration. The pair of loading valves may be similar or dissimilar to one another. 
         [0027]    The described features may be combined as appropriate, as would be apparent to one of skill in the art reading this disclosure. Many of these features and combinations will be more readily apparent with reference to the following detailed description and the appended drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appreciated. 
           [0029]      FIG. 1  is a schematic of an embodiment of the VPC power module and manifolds illustrating the plug-and-play versatility of the system; 
           [0030]      FIG. 2  is a schematic of an embodiment of a double-acting system with two normally-closed loading valves illustrating a condition where the downstream pressure set-point is satisfied and the system is in a steady state with the process control valve at a first position; 
           [0031]      FIG. 3  is a schematic of the embodiment of  FIG. 2  illustrating a condition where the downstream pressure rises above a set-point and the process process control valve reacts to close further; 
           [0032]      FIG. 4  is a schematic of the embodiment of  FIG. 2  illustrating a condition where the downstream pressure returns to a set-point and the system is again in a steady state with the process control valve at a second position; 
           [0033]      FIG. 5  is a schematic of the embodiment of  FIG. 2  illustrating a condition where the downstream pressure falls below a set-point and the process process control valve reacts to open further; 
           [0034]      FIG. 6  is a schematic of the embodiment of  FIG. 2  illustrating a condition where the downstream pressure returns to a target pressure (i.e., set-point) and the system is once again in a steady state with the process control valve at a third position; 
           [0035]      FIGS. 7A-E  are a sequence of schematics, similar to  FIGS. 2-6 , of an embodiment of a double-acting system with two normally open loading valves illustrating steady state and upset conditions of the system; 
           [0036]      FIGS. 8A-E  are a sequence of schematics, similar to  FIGS. 2-6 , of an embodiment of a single-acting system with two normally-closed loading valves illustrating steady state and upset conditions of the system; 
           [0037]      FIGS. 9A-E  are a sequence of schematics, similar to  FIGS. 2-6 , of another embodiment of a single-acting system with the addition of a “derivative” function adjustment and with two normally-closed loading valves illustrating steady state and upset conditions of the system; 
           [0038]      FIG. 10  is a cross-sectional view of one valve section of an embodiment of the VPC power module showing the interchangeability of a normally-closed loading valve and a normally-open loading valve; 
           [0039]      FIG. 11  is a schematic illustrating a single-acting VPC with a normally-closed loading valve configuration and a proportional valve position feedback acting as a pneumatic valve positioner; 
           [0040]      FIG. 12  is a schematic showing a system having a VPC having dissimilar normally-closed loading valve and a normally-open loading valve with independent sensitivity adjustments for each loading valve; 
           [0041]      FIGS. 13-13   d  are various views of an optional valve manual override (VMO), including illustrating the VMO in automatic mode, neutral mode, open mode, and closed mode, and demonstrating manifold configuration between VMO body and pneumatic connection ports; 
           [0042]      FIGS. 14 and 15  illustrate an embodiment of the VPC power module and the interchangeable manifolds; and 
           [0043]      FIGS. 16A /B through  29 A/B are schematics of the numerous system variations ( FIGS. 16A-29A ) and the corresponding VPC model ( FIGS. 16B-29B ). 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0044]    While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to embodiments illustrated. 
         [0045]    Referring to  FIGS. 1-29 , there are illustrated embodiments of a fluid line control system, the system being generally referenced in the drawing figures by the numeral  10 . The control system  10  is comprised of a fluid line  12  having a process control valve  14  coupled therein and a variable pressure controller (VPC)  20  indirectly coupled to the process control valve  14 . The process control valve  14  has a supply side pressure (P 1 ) and a delivery side pressure (P 2 ), the latter of which is controlled through operation of the process control valve  14 . The VPC  20  is comprised of a power module  22  and interchangeable manifolds  30  to achieve different configurations/models, as further explained below. 
       Process Control Valve 
       [0046]    In the embodiment of  FIGS. 2-6 , the process control valve  14  is directly operated by a pneumatic actuator  32  having a first (or upper) pressure chamber  34  and a second (or lower) pressure chamber  36 . The pressure chambers,  34  and  36 , are fluidly coupled to first and second loading valves,  40  and  42 , respectively, through adjustable orifices,  44 A and  44 B. In the double-acting models of the system  10 , the process control valve is operated pneumatically, requiring the fluid pressures in the first and second chambers,  34  and  36 , to move the actuator in either direction. Comparatively, in the single-acting embodiments, the process control valve  14  includes a spring-piston actuator  32  (e.g.,  FIG. 18A ), where the fluid pressure of the system  10  is used to drive the actuator in a single direction against the force of the spring  41 . Alternatively, the actuator of the process control valve  14  may be operated by a spring/diaphragm  50  (e.g.,  FIG. 21A ). Either of the embodiments described for actuator  32  of the process control valve  14  for the single-acting models may be reversed for particular applications (e.g.,  FIGS. 19 and 26 ). 
       Loading Valves 
       [0047]    The loading valves of the VPC power module  22  are preferably loading valves,  40 ,  42 , which are preferably normally closed valves. These valves operate in response to movement of an internal mechanism  16 , which is in turn responsive to a control spring  24  and sensing diaphragm  26  coupled to a sensing pressure at the delivery side of the process control valve  14 . A set-point of the delivery side pressure (P 2 ) is set via set-point adjustment screw  28 . Alternatively, as shown in  FIG. 10 , the valves may utilize loading valves  45  ( FIG. 10 ), which are of a normally-open configuration. As two loading valves are used, the pair of loading valves may be similar (i.e., both normally closed loading valves or both normally open loading valves) or the valves may be dissimilar (i.e., one normally closed loading valve and one normally open loading valve). 
       Operation of Double-Acting VPC System 
       [0048]    Generally speaking, operations of the system  10  using different models of the VPC  20  are similar. In a double-acting model, when the sensing pressure is equal to the VPC set-point, the net force on the VPC power module  22  is zero. This is the equilibrium or “balanced” condition where the sensing pressure that pushes down on a sensing diaphragm  26  and the force of the control spring  24  that pulls up on the sensing diaphragm  26  are equal. When the VPC  20  achieves equilibrium (e.g.,  FIG. 2 ), the top loading valve  40  and bottom loading valve  42  will remain closed maintaining a constant output pressure to the top and bottom chambers,  34  and  36 , respectively, of the process control valve actuator  32 . The VPC will exhibit zero emissions at this state. 
         [0049]    From the balanced position two possible scenarios can occur: the sensing pressure can rise above the set point, or the sensing pressure can fall below the set-point. If the sensing pressure rises above the VPC set-point (e.g.,  FIG. 3 ), the net force on the VPC power module  22  is downward. The top loading valve  40  will open and divert pressure from the top chamber  34  of the double acting actuator  32  to exhaust. The bottom loading valve  42  will remain closed and full supply pressure shall continue to be applied to the bottom chamber  36  of the double acting actuator  32 . The combination of these actions creates a differential pressure to be applied to the double acting actuator  32  that will move the process control valve  14  toward the closed position. 
         [0050]      FIG. 4  illustrates the resulting corrective action of the closed process control valve. 
         [0051]    Conversely, if the sensing pressure falls below the VPC set-point (e.g.,  FIG. 5 ), the net force on the VPC power module  22  is upward. The bottom loading valve  42  will open and divert pressure from the bottom chamber  36  of the double acting actuator  32  to exhaust. The top loading valve  40  will remain closed and full supply pressure shall continue to be applied to the top chamber  34  of the double acting actuator  32 . The combination of these actions creates a differential pressure to be applied to the double acting actuator  32  that will move the process control valve toward the open position. 
         [0052]      FIG. 6  illustrates the resulting corrective action of the open process control valve. 
         [0053]    Remaining with double-acting VPC model of  FIGS. 2-6 , a step-wise operation of an embodiment of the system  10  is provided below. 
         [0054]    With reference to  FIG. 2 , the following is illustrated:
       a. The energy to operate the actuated process control valve  14  is obtained from the differential between supply gas pressure and exhaust pressure.   b. When the downstream pressure (P 2 ) is equal to a set-point a force equilibrium will exist between the VPC sensing diaphragm  26  and the control spring  24 .   c. The force equilibrium results in the VPC internal mechanism  16  being centered.   d. With the VPC mechanism  16  centered, the first loading valve  40  and the second loading valve  42  remain closed and full supply pressure passes through the adjustable orifices,  44 A and  44 B, and load both pressure chambers  34  and  36  of the pneumatic actuator  32  equally.   e. At the steady state centered position, the VPC  20  achieves ZERO steady exhaust.       
 
         [0060]    With reference to  FIG. 3 , the following is illustrated:
       a. When the downstream pressure (P 2 ) is rises above set-point the VPC sensing diaphragm  26  force will exceed the control spring  24  force.   b. The downward force imbalance results in the VPC internal mechanism  16  shifting downward.   c. With the VPC internal mechanism  16  shifting downward, the first loading valve  40  will open slightly and second loading valve  42  will remain closed.   d. When the first loading valve  40  opens it causes the pressure loading the first pressure chamber  34  of the pneumatic actuator  32  to be directed to the exhaust  46 .   e. The second loading valve  42  remains closed causing full supply gas pressure to pass through the adjustable orifice  44  loading the second pressure chamber  36  of the valve actuator  32 .   f. With the pressure differential across the valve actuator  32 , the process control valve  14  moves toward the CLOSED position.       
 
         [0067]    With reference to  FIG. 4 , the following is illustrated:
       a. When the process control valve  14  moves toward the CLOSED position, the downstream pressure will drop and return to a value equal to the set-point.   b. When the downstream pressure (P 2 ) is equal to set-point, a force equilibrium will exist between the VPC sensing diaphragm  26  and the control spring  24 .   c. The force equilibrium results in the VPC internal mechanism  16  being centered.   d. With the VPC internal mechanism  16  centered, the first loading valve  40  and the second loading valve  42  remain closed and full supply pressure passes through the adjustable orifices  44 A and  44 B and loads both pressure chambers,  34  and  36 , of the pneumatic actuator  32  equally.   e. At the steady state centered position, the VPC  20  achieves ZERO steady exhaust.       
 
         [0073]    With reference to  FIG. 5 , the following is illustrated:
       a. When the downstream pressure (P 2 ) is falls below the set-point the VPC control spring  24  force will exceed the sensing diaphragm  26  force.   b. The upward force imbalance results in the VPC internal mechanism  16  shifting upward (as indicated by the arrow).   c. With the VPC internal mechanism  16  shifting upward, the second loading valve  42  will open slightly and first loading valve  40  will remain closed.   d. When the second loading valve  42  opens, it causes the pressure loading the second pressure chamber  36  of the pneumatic actuator  32  to be directed to the exhaust  46 .   e. The first loading valve  40  remains closed, causing full supply gas pressure to pass through the adjustable orifice  44  loading the first pressure chamber  34  of the valve actuator  32 .   f. With the pressure differential across the valve actuator  32 , the process control valve  14  moves toward the OPEN position.   g. When the process control valve  14  moves toward OPEN position, the downstream pressure will rise and return to a value equal to the set-point.       
 
         [0081]    With reference to  FIG. 6 , the following is illustrated:
       a. When the downstream pressure (P 2 ) is equal to a set-point, a force equilibrium will exist between the VPC sensing diaphragm  26  and the control spring  24 .   b. The force equilibrium results in the VPC internal mechanism  16  being centered.   c. With the VPC internal mechanism  16  centered, the first and second loading valves,  40  and  42 , remain closed and full supply pressure passes through the adjustable orifices,  44 A and  44 B, and loads both pressure chambers,  34  and  36 , of the pneumatic actuator  32  equally.   d. At the steady state centered position, the VPC  20  achieves ZERO steady exhaust.       
 
         [0086]    While  FIGS. 2-6  illustrate and the above describes a double-acting actuator operated process control valve using normally-closed loading valves, it should be understood that systems using the normally-open loading valves operate similarly. For example, the steady state and upset state conditions are illustrated in  FIGS. 7A-E  featuring a VPC with normally-open valves. 
       Operation of Single-Acting VPC System 
       [0087]    Similarly, referring to  FIGS. 8A-E  and  9 A-E, a single-acting version can be used and works similarly. A notable difference is that the first loading valve  40  and the second loading valve  42  would be connected in common and would work synchronously. These valves,  40  and  42 , would still be normally closed and would translate to “cylinder load” and “cylinder unload.” 
         [0088]    That is, for single-acting systems where a single pressure output is involved, there shall be one valve designated as the “load” valve and one valve designated as the “unload” valve. Each valve shall be normally closed for this type of system. The “load” and “unload” valves are connected to a common pressurized system. In this configuration, the VPC  20  has three different states: (1) steady state; (2) unloading state; and, (3) loading state. 
         [0089]    In the steady state, both the “load” and “unload” valves are closed, resulting in no pressurizing or depressurizing of the pneumatic actuator system. The process control valve  14  is said to be in a steady state or static. 
         [0090]    When an upset in the process variable occurs, the VPC  20  may enter the unload state or loading state. In the unload state, the force unbalance between the VPC sensing diaphragm  26  and the control spring  24  causes a shift of the VPC  20  to open the “unload” valve and maintain the “load” valve in a closed position. This causes the system  10  to vent or exhaust pressure from the pneumatic actuator  32  resulting in a new position of the process control valve  14 . Conversely, when an upset occurs to place the VPC  20  in the “loading” state, the unbalance between the sensing diaphragm  26  and the control spring  24  causes a shift of the VPC  20  to open the “load” valve and keep the “unload” valve closed. This causes the system  10  to increase pressure to the pneumatic actuator  32  resulting in a new position of the process control valve. Ultimately, in both cases, the new position of the process control valve  14  will result in attainment of equilibrium and return to the steady state, as described above. 
         [0091]    Additionally, in the single-acting (SA) model of the VPC, when the sensing pressure is equal to the VPC set-point, the net force on the VPC power module  22  is zero. As noted, this is an equilibrium condition where the sensing pressure that pushes down on the sensing diaphragm  26  and the force of the control spring  24  that pulls up on the sensing diaphragm  26  are equal. When the VPC  20  achieves this equilibrium, the supply loading valve  40  and exhaust loading valve  42  will remain closed maintaining a constant output pressure to the process control valve  14 . The VPC  20  will exhibit zero emissions at this state. 
         [0092]    During operation, the equilibrium or steady state (static) is preferred, so the system operates to return to this state whenever an upset occurs. As noted, two possible scenarios can occur from the balance state: the sensing pressure can rise above the set point or fall below the set point. If the sensing pressure rises above the VPC set-point, the net force on the VPC power module is downward. The exhaust loading valve will close or stay closed. The supply loading valve opens, increasing the flow of supply gas to the output port. The combination of these actions creates a rise in output pressure. If the sensing pressure falls below the VPC set-point the net force on the VPC power module is upward. Now the supply loading valve will close or stay closed and the exhaust loading valve opens, increasing the flow of gas to the exhaust port. The combination of these actions decreases the output pressure. In order to control how much gas passes through the loading valve, adjustable orifices are installed to restrict the flow via the supply and the exhaust. 
       Modularity of VPC 
       [0093]    A key aspect of the system  10  is the modularity of the VPC  20 . A modular format of the VPC  20  is illustrated in  FIG. 1 . The modular format of power modules  30  and the internal loading valve logic ( FIG. 10 ) provide the ability to configure the device for double-acting (DA) output or single-acting (SA) output within the same system. Existing technology does not offer a modular format that allows reconfiguration between the double-acting output and single-acting output configurations. 
         [0094]    Accordingly, the VPC  20  is capable of being configured in a number of different models as a result of the adaptability of the single platform power module  22  and the various “plug-and-play” modules. Exemplary embodiments of these “plug-and-play” modules (labeled 1-4) to form discrete VPC models (labeled 1-5, with corresponding labeled modules forming the particular VPC model) are set forth in  FIG. 1 . Each model 1-5 corresponds to a set of operating parameters referenced in TABLE 1 below. More detailed illustrations and descriptions of such modules and VPC models, as well as possible alternatives and accessory devices, follow. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Controller Model 
                 VPC-SA-BV 
                 VPC-SA-BV-ID 
                 VPC-SA-BV-GAP 
                 VPC-DA-BV 
                 VPC-DA-SN 
               
               
                   
               
             
             
               
                 Type 
                 Variable 
                 Variable 
                 Discrete 
                 Variable 
                 Variable 
               
               
                   
                   
                   
                 (On-Off) 
               
             
          
           
               
                 Outputs 
                 Single Acting (1) 
                 Double Acting (2) 
               
             
          
           
               
                 Internal Valve 
                 Normally-Closed Loading Valve 
                 Normally 
               
               
                 Logic 
                   
                 Open Loading 
               
               
                   
                   
                 Valve 
               
             
          
           
               
                 Setpoint Range 
                 1.25-1500 psig (9.0-10,342 kPa) 
               
               
                 Temperature Range 
                 −20° F. to +160° F. (−29° C. to +71° C.) 
               
               
                   
               
             
          
         
       
     
         [0095]    The various VPC models are so configured to be applicable to different fluid systems. In operation, the embodiments operate in a similar manner, with variations such as flow direction, valving, etc., dictated by the accompanying modules and accessory devices. And the simple modularity allows conversion between models. For example, the VPC has the ability to convert between a normally open loading valve style (SN) to normally closed loading valves (BV). Further, the manifolding provided by the power module  22  provides the ability to convert to and from single acting to double acting models. Additionally, when configured as a single acting model, the VPC can convert between “direct acting” and “reverse acting” control logic. 
         [0096]    Referring to  FIGS. 16-29  (A and B), the modularity of the VPC  20  can be most readily appreciated. In these figures the numerous VPC models are shown schematically placed within a fluid control system  10  (i.e.,  FIGS. 16A-29A ) and labeled for adjusting the set-point screw  28  and sensitivity (i.e.,  FIGS. 16B-29B ). 
       VPC Modules 
       [0097]    Referring to  FIGS. 1, 14 and 15 , several different manifolds  30  are illustrated. These manifolds  30  connectable to the VPC power module  22  and create the various VPC models described. As illustrated, the individual manifolds  30  may include various configurations, channels and adjustable orifices to accommodate single-acting and double-acting configurations, as well as normally-closed loading valve and normally-open loading valve configurations. The manifolds  30  connect and bolt (or otherwise lock) onto the power module  22 . 
       System Accessories 
       [0098]    Referring now to  FIGS. 11-13 , numerous system  10  accessories can be viewed. These accessories also add to the modularity of the VPC  20 . As noted above, the VPC  20  may be configured with either normally open loading valves (seat &amp; nozzle valves  45 ) or normally closed (loading valves  40 ) internal logic using the same VPC base platform  22 . Interchangeable internal valve format “Logic Exchange” (see  FIG. 10 ) allows the system  10  to be configured for multiple control applications. 
         [0099]    As shown in  FIG. 1 , the “connecting” manifolds  23  of the VPC power module  22  provide unique flow conditioning that optimizes flow characteristics of internal logic (loading valves  40  and  42 ), allowing greater control capabilities of the VPC  20 . This is particularly important when coupled with additional control devices such as a volume booster  33  (see  FIG. 12 ) and a pneumatic positioner  35  (see  FIG. 11 ). Existing technology does not integrate any “flow conditioning” via manifolding, which lessens control capabilities. 
         [0100]    The VPC derivative adjustment (orifice) is pneumatically coupled with the VPC output pressure via installation in same manifold which provides improved control capabilities. The derivative adjustment is an adjustable orifice (restriction) that is installed in parallel with the output to the control element (actuator  32  or pneumatic positioner  35 ) with a volume tank  37  installed downstream of the derivative adjustment. The resulting configuration provides for a delayed response of the VPC output signal to the control element (actuator  32  or valve positioner  35 ). The derivative adjustment affects the rate of response of the output to the control element (actuator  32  or valve positioner  35 ). Existing systems utilize a derivative adjustment (orifice) that is installed as a separate component (adjustable orifice) from the output function which does not provide the same optimized characteristics as achieved in the VPC  20  of the present system  10 . 
         [0101]    The base VPC  20  of system  10  offers numerous additional advantages over existing technology. As shown in  FIG. 12 , the VPC  20  allows incorporation of two (2) dissimilar internal valves (i.e., normally-closed loading valve and normally-open loading valve) to achieve a completely new control configuration for application optimization. Current technology must utilize two (2) identical internal loading valves due to limitations of design. Also shown, the VPC  20  also allows incorporation of two (2) independent sensitivity adjustments for each internal loading valve to achieve a completely new control configuration for application optimization. Current technology is limited to only a single sensitivity adjustment that affects both internal loading valves. 
         [0102]    The VPC  20  may also be configured as a proportional device with a mechanical feedback to achieve a “diaphragm type” valve positioner  39 , as shown in  FIG. 11 . Current technology incorporates a mechanical feedback that directly couples the diaphragm module with the power module in a linear arrangement. A diaphragm type valve positioner  39  incorporates a mechanical feedback that separates the diaphragm module and the power module. The design incorporates pivoted beam component to couple the power module  22  and the diaphragm module  39 , also shown in  FIG. 11 . 
         [0103]    The base VPC  20  provides Integral function (I) and Derivative function (D) adjustments. More demanding control applications may require addition of a Proportional function (P) adjustment in a “PID” type controller. The present system  10  utilizes a continuous type Proportional function (P) adjustment that incorporates a pivoted beam with an adjustable fulcrum. Existing technology does not have a continuous Proportional function (P) adjustment, but utilizes a selection of interchangeable components to achieve only discrete Proportional function (P) values. 
         [0104]    Optionally, with reference to  FIG. 13-13   d,  the system  10  may include a valve manual override (VMO)  46 , which is a six-way, five-position valve utilized in conjunction with the VPC  20 . The VMO  46  provides an ability to override any of the system configurations and manually operate the process control valve  14  to which the VPC  20  is coupled. In contrast, current technology is installed via threaded plumbing connections and multiple pneumatic tubing lines. The current system  10  allows the VMO  46  to be installed as an integral component with the VPC  20  utilizing the unique manifold  23 , thereby minimizing the need for any external plumbing connections and simplifying the design. Additionally, the manifolds  23  of the system  10  allow for installation and removal of the VMO  46  without removal of any threaded plumbing fittings. Rotary type VMO and linear ported type VMO may be used. In the case of the rotary type VMO, the device is used to interrupt and allow manual control of the pneumatic output of the pilot by manually rotating ports. The linear ported type VMO also interrupts and allows manual control of the pneumatic output of the pilot, but does so by shifting of a linear ported valve system. 
         [0105]    Other key alternate components and embodiments of the system  10  and VPC  20  are set forth in the paragraphs below. 
         [0106]    As previously mentioned, the VPC  20  can use two different internal valves fluidly coupled to the actuator  32 . Known existing designs have always used the same internal valves in order to achieve a control function. Comparatively, the loading valves of the present system  10  can be either normally-open type loading valves or normally-closed type loading valves. For example, the VPC  20  can be constructed using one normally-open type loading valve and one normally-closed type loading valve. Additional adjustments would be needed in order to tune each loading valve individually, but those skilled in the art would understand how to make such adjustments. Such a configuration can be used, for example, where a volume booster  33  ( FIG. 12 ) is needed in one direction but not is the opposite direction. 
         [0107]    As those skilled in the art will appreciate, existing pneumatic controllers are available in two configurations: Bourdon tube plus relay and direct diaphragm. The Bourdon tube plus relay is available with all variable P+I+D functions. The direct diaphragm controller is only available with variable I+D and selectable P functions. However, the VPC  20  can also be built on the diaphragm principal with all P+I+D functions available as variable. 
         [0108]    With respect to the use of a pneumatic positioner  35 , existing devices are available as one of either a relay type, spool valve type or diaphragm type positioner. The relay positioner and spool valve positioner are both available with rotary or linear feedback. However, the diaphragm positioner is currently only available with a linear feedback. The present system  10  provides a diaphragm positioner with rotary feedback or linear feedback. The rotary feedback will have a feedback beam driven by the sensing diaphragm and counterbalanced by the power diaphragms and range extension spring. 
         [0109]    Other possible design alterations include the following:
       A. Combining I and D orifice in one manifold;   B. Using a smaller volume tank;   C. Using ID controller as the first stage cut controller over PI and over PID;   D. Use of 001″ hard coat anodizing to create a barrier between aluminum and SS screws, which eliminates electrolysis effect and aluminum corrosion;   E. 5.225 and 1500 sensing chambers built as independent chambers versus existing technology design; and   F. Six common springs for all design versus several cartridges for existing technology.       
 
         [0116]    The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants&#39; contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.