MANIFOLD ARRANGEMENT

RELATED APPLICATIONS

[0001] The present application claims the benefit of two pending United States provisional applications: serial number 60/829,751 filed on October 17, 2006, for SIDE PORTED MANIFOLD, and serial number 60/890,571 filed on February 19, 2007, for SENSOR MOUNTING ARRANGEMENT FOR MANIFOLD, the entire disclosures of which are fully incorporated herein by reference.

BACKGROUND

[0002] Numerous industries and technologies utilize process fluids, including biopharmaceutical, petrochemical, semiconductor and so on. The process fluids may at times need to be sampled and analyzed, or the flow of such fluids may need to be controlled as part of a process. Many different types of flow control devices have been developed to control the flow of process fluids. One such device is generally known as a stream selector which may include one or more valves that control flow. Some stream selectors are pneumatically actuated, meaning that pressurized air moves a piston that opens and closes the various valves. Recently, modular surface mount technology has been receiving increased attention due to ease of assembly, ease of replacement of various surface mount components, and space and weight savings. Typically, a substrate is provided with flow passages for the process fluid that communicate with one or more flow control components mounted on the surface of the substrate. Separate lines are used to provide pressurized air to the pneumatic devices.

[0003] Solenoid actuated valves are also well known and commonly used throughout many industries. Typical solenoid valves include a solenoid energized plunger that moves in response to voltage applied across the solenoid coil. Often times, the plunger is spring biased so

that a higher voltage is used to pull-in or actuate the valve and a lower voltage is used to hold-in or maintain the valve actuated. A common technique is to ballast a higher input voltage to a lower voltage to reduce coil heating. This approach, however, is not conducive to an intrinsically safe design.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Fig. 1 is a functional block diagram of a system for controlling fluid flow, incorporating various inventive aspects of this disclosure;

[0005] Fig. 2 is an exemplary functional block diagram of a solenoid actuation circuit for a single solenoid;

[0006] Fig. 3 is an exemplary timing diagram for the circuit of Fig. 2;

[0007] Fig. 4 is another exemplary functional block diagram of a solenoid actuation circuit for multiple solenoids;

[0008] Fig. 5 is a simplified schematic of an exemplary embodiment of a side port manifold arrangement;

[0009] Figs. 6 and 7 are front and back perspectives of a manifold arrangement such as may be used for the process valves and solenoid valves represented in Fig. 1 ;

[0010] Fig. 8 is a view similar to Fig. 7 but with a cover removed to illustrate the solenoid valves;

[0011] Fig. 9 is a plan view of the arrangement of Figs. 6-8;

[0012] Figs. 6 A and 9 A illustrate an alternative mounting arrangement for the proximity sensors of the valve manifold arrangement;

[0013] Fig. 10 is a longitudinal section view taken along the line 10-10 in Fig. 9;

[0014] Fig. 11 is a lateral section view taken along the line 11-11 in Fig. 9;

[0015] Fig. 12 is an exploded perspective of the assembly of Figs. 6-9;

[0016] Fig. 13 is a perspective of a mounting bar used in the assembly of Figs. 6-9;

[0017] Fig. 14 is a cross-sectional view of a side port manifold used in the assembly of

Figs. 6-9;

[0018] Fig. 15 is a lateral section view taken along line 15-15 in Fig. 9.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0019] The disclosure is directed to systems for controlling fluid flow, and also methods and apparatus for controlling operation of a solenoid or solenoid actuated valve. Such solenoid and solenoid valve aspects may be used, for example, in the described system for controlling fluid flow. Although various inventive aspects of the present disclosure are described in terms of the exemplary embodiments utilizing stream selector valves, solenoid pilot valves and exemplary related circuits, such descriptions are intended to be exemplary and not limiting. Inventive aspects relating to solenoid and solenoid valve control may find application anywhere a solenoid or solenoid actuated valve is used. The inventive aspects as to fluid flow control, side port manifold, solenoid control and solenoid valve control may also find application in different flow control systems that utilize flow control devices other than stream selectors or pneumatically actuated valves.

[0020] While various inventive aspects, concepts and features of the inventions may be described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects, concepts and features may be used in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present inventions. Still further, while various alternative embodiments as to the various aspects, concepts and features of the inventions—such as alternative materials, structures, configurations, methods, circuits, devices and components, software, hardware, control logic,

alternatives as to form, fit and function, and so on~may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or later developed. Those skilled in the art may readily adopt one or more of the inventive aspects, concepts or features into additional embodiments and uses within the scope of the present inventions even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the inventions may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present disclosure, however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated. Moreover, while various aspects, features and concepts may be expressly identified herein as being inventive or forming part of an invention, such identification is not intended to be exclusive, but rather there may be inventive aspects, concepts and features that are fully described herein without being expressly identified as such or as part of a specific invention, the inventions instead being set forth in the appended claims. Descriptions of exemplary methods or processes are not limited to inclusion of all steps as being required in all cases, nor is the order that the steps are presented to be construed as required or necessary unless expressly so stated.

[0021] With reference to Fig. 1, a system for controlling fluid flow is generally indicated by the numeral 10. The system 10 may be used, for example, to control the flow of a process media or fluid F, and may, for example, be used to control N process streams where N>1. A typical application of the system 10 may be in the instrumentation field, for example, sampling and analyzing various process fluids F _N used in or by a process P. For example, one type of process may be chromatography of chemical liquid, gas and/or vapor. Many other examples will be readily apparent to those skilled in the art.

[0022] Process fluid flow may be controlled for example by a process valve 12.

Typically a separate process valve (12 _! -12 _N ) is used for each process fluid, process or sampling/analyzer. An example of a process valve 12 is a SSV Series stream selector, model SS- SSV- V-x -F2 available from Swagelok Company, Cleveland, Ohio. Many other types of process

valves or other flow control devices may be used to control flow of the process fluid. In the exemplary embodiments of this disclosure the process valve(s) 12 is pneumatically actuated.

[0023] Pressurized air +PA is provided to each of the process valves 12 by a respective control device 14. In the exemplary embodiment, each control device 14 may be realized in the form of a solenoid actuated valve 16, such as a pilot valve model EI-2M-15.5. available from Clippard Instrument Laboratory Inc. For separate individual control of each process valve 12 _N there may be provided a respective pilot valve 16 _N - Alternatively, a single pilot valve may be used to control one or more or all of the process valves when simultaneous operation may be desired. The solenoid valves 16 provide pressurized air since the process valves are pneumatic, but other solenoid actuated valves may be used as needed based on the type of process valve used. Whenever it is desired to actuate a process valve 12, the corresponding pilot valve 16 is opened to supply pressurized air to the process valve.

[0024] Control of the pilot valve 16 _N ~ and thus control of the process valves 12N and process fluid F _N flow as well ~ is carried out by a solenoid actuation or control circuit 18. The actuation circuit 18 controls which solenoid valves 16 _N are actuated and when, in response to a command signal 20. The command signal 20 may be any signal that is recognized by the actuation circuit 18 to open and close the various solenoid valves 12 _N and 16 _N - Thus, the command signal 20 is provided by a controller (not shown) that determines when the various valves 16 _N are to be actuated as part of the overall process P. The command signal 20 may be coupled to the actuation circuit 18 by any convenient means such as a network bus, wireless, fiber optic and so on. The command signal 20 may also be an operator controlled or manually actuated control signal.

[0025] Fig. 2 illustrates an exemplary functional block diagram of the solenoid actuation or control circuit 18. Fig. 3 is an exemplary timing diagram for the circuit of Fig. 2. Although Fig. 2 illustrates a control circuit for a single solenoid, in an alternative embodiment the control function may be implemented for two or more solenoids as illustrated in Fig. 4.

[0026] With reference to Figs. 2 and 3, the circuit 18 includes a boost circuit 22, a logic circuit 24 and a solenoid circuit 26. Physically these circuits may all be contained on a common

circuit board but they need not be so arranged. Moreover, the solenoid circuit 26 is illustrated in schematic form to include the solenoid coil Ci though in practice the coil Ci may physically be part of another component such as the solenoid valve 16 of Fig. 1. A typical solenoid includes a coil and a plunger, but for purposes of the electrical circuit only the coil is represented.

[0027] An input 28 receives a voltage VCC. This voltage typically will be but need not be a digital signal and in the exemplary embodiment may be about +9.5 VDC. This voltage is selected based on overall circuit parameters and a minimum hold-in voltage across the coil Ci needed to keep the solenoid energized after is has pulled-in. This generally minimized voltage level significantly reduces power consumption when the solenoid is energized, and also reduces voltage to the circuit 18 to meet intrinsic safety (IS) requirements for those applications where IS is either mandated or desirable.

[0028] The voltage VCC is coupled to the high side of the solenoid coil Ci through a blocking diode 30. The voltage VCC also is input to the boost circuit 22. The boost circuit 22 may be realized in many different forms and configurations as will be readily apparent to those skilled in the art. The function of the boost circuit is to provide at its output 32 an increased voltage VPULL-IN that is sufficient to ensure that the solenoid coil Ci will develop enough magnetic flux to energize or pull-in the solenoid. Thus, the output 32 of the boost circuit 22 is coupled to the high side of the solenoid coil Ci (noting that the low side of the coil typically is at ground). The blocking diode 30 isolates the boost circuit output from the VCC input.

[0029] The boost circuit 22 may be realized using any well known circuit design, such as for example, a capacitor charge pump, Dickson charge pump, voltage doubler, or boost switch mode DC to DC converter to name a few examples, or a custom circuit may be used. The boost circuit output 32 may simply be a multiple of the input voltage VCC but need not be. Figs. 5A-B illustrates one embodiment of a boost circuit that may be used.

[0030] The logic circuit 24 may be used to control timing of the solenoid actuation by controlling the timing of when the pull-in voltage and hold-in voltage are applied across the solenoid coil Cj. The logic circuit 24 may be realized in many different ways including digital logic, part of a controller, analog circuits and so on. The function of the logic circuit 24 is such

that when a command signal 20 input is received ~ indicating that the solenoid valve 14 is to open and thus activate the process valve 12, the logic circuit produces a first or ENABLE output 34 to the boost circuit 22. This enable signal causes the boost circuit to charge up. When the ENABLE signal 34 is removed, the output 32 is an open circuit or high impedance so as to not load the input VCC.

[0031] The ENABLE signal 34 is applied for a suitable time period to allow the boost circuit to charge. After an appropriate delay, the logic circuit produces and output H or HOLD signal 36 which actuates a control switch 38. The control switch 38 is in series between the high side of the coil Ci and a common node 40 for the pull-in voltage VPULL-IN and the blocking diode 30. The control switch 38 may be any suitable switch such as an FET, relay and so on.

[0032] When the control switch 38 is closed, the higher voltage VPULL-IN is applied across the coil Ci to energize the solenoid. The ENABLE signal is then removed, which causes the boost circuit output 32 to drop out. This causes the voltage across the coil to drop to about VCC or the hold-in voltage. The solenoid can be deenergized by removing the signal HOLD which opens the switch 38 to isolate the coil Ci from the node 40. A flyback diode 42 may be provided to suppress any transient spikes when the control switch 38 is opened. The HOLD signal may be removed, for example, when the command input 20 is removed.

[0033] Fig. 3 is an exemplary timing diagram for the circuit of Fig. 2. At time TO the

COMMAND signal enables the boost circuit 22 to charge up to voltage VPULL-IN that is at least sufficient to energize and pull-in the solenoid. At time Tl the HOLD signal 36 closes the control switch 38 and the solenoid is energized. The ENABLE signal 34 goes low after pull-in so that the voltage across the coil Ci drops to about VCC or the hold-in voltage needed to keep the solenoid energized. At time T2 the COMMAND signal goes low causing the HOLD signal to go low and opening the control switch 38 which deenergizes the solenoid. The duration of the time periods Tl and T2 will vary depending on the components used and overall system design. The boost circuit 22 thus functions to provide an on demand pulse for solenoid actuation that avoids the need to supply or store a high voltage to the circuit. This is more conducive to an overall intrinsically safe design and also has a default voltage of 0 volts.

[0034] Fig. 4 illustrates a control circuit 50 that may be used for controlling multiple solenoids. The basic circuit is similar to Fig. 2 except that there are N solenoids with a corresponding N solenoid circuits 52 _N . In this embodiment a single boost circuit 54 may be used to provide the pull-in voltage needed by the solenoids. The input voltage VCC may also be used by all the solenoids.

[0035] In the embodiment of Fig. 4, individual and separate control of each solenoid is effected by using multiple input COMMAND signals 56 _N and multiple output HOLD signals 58 _N - Because the pull-in voltage 60 is shared by more than one solenoid, each solenoid circuit 52 _N includes a second control switch 62. This switch responds to an additional output from the logic circuit 64 which is identified as the PULL-IN signal 66. The second control switch 62 is used to isolate the non-selected solenoids when the boost circuit output is used to energize one or more of the solenoids. For example, if solenoid circuit 1 is to be energized, a command signal CMDl is received and the ENABLE signal EN 68 causes the boost circuit 54 to charge up. After an appropriate delay, the PULL-IN signal Pl goes high and the HOLD signal Hl goes high, thus energizing the solenoid associated with solenoid circuit 1 (52i). The ENABLE signal 68 may still be a pulse that goes low after the solenoid is pulled in. Alternatively, the signal 68 may be a steady output voltage since the solenoid circuits 52N include the second control switch 62. The solenoids are deenergized by removing the COMMAND signal to cause the HOLD signal to go low and open the first switch Sl.

[0036] Note that the embodiment in Fig. 4 may be modified to control two or more solenoids to pull-in at the same time, either by receiving simultaneous COMMAND signals or by sharing common PULL-IN and HOLD signals.

[0037] Reference may be made to the above incorporated provisional applications for an exemplary embodiment of a boost circuit and related circuits of the embodiment of Figs. 1-4, however, as noted, the inventive aspects of the solenoid control functions may be carried out with any of a wide variety of circuits and techniques that take a first voltage, boost or increase the first voltage to a second voltage for a period of time that is sufficient to pull-in a solenoid, and then reduce to the first voltage that is sufficient to hold in the solenoid.

[0038] With reference next to Fig. 5, we show a simplified schematic of a manifold arrangement 300, such as may be used, for example, for the process valves and solenoid valves in the Figs. 1-4 embodiment. Figs. 6-15 illustrate a detailed exemplary embodiment of the features of Fig. 5.

[0039] In Fig. 5, a first support block 302 may be fixed to a surface X by any convenient technique such as a bolt 304, for example. The surface X may be part of a plate, substrate, other blocks and so on. The first support block 302 has one or more surface mount components 306 mounted thereon.

[0040] A second support block 308 is provided and has one or more surface mount components 310 mounted thereon. In this example, the second support block 308 is freely associated with the surface X prior to final assembly so that as part of a final assembly process there is relative movement permitted between the first support block 302 and the second support block 308. Alternatively, the second support block 308 may be fixed to the surface X with the first support block 302 free to move relative to the second support block 308 during final assembly. The relative movement is used in order to bring two facing surfaces 312 and 314 towards each other to establish a face seal therebetween. Note that in Fig. 5 various gaps are exaggerated for clarity.

[0041] A seal 316, such as for example an o-ring seal or other suitable seal, may be provided between the two facing surfaces 312, 314 so as to effect a face seal at the interface therebetween. The face seal 316 provides a fluid tight coupling between a first flow path 318 in the first support block 302 and a second flow path 320 in the second support block 308. As an example, the surface mount component 306 may be a pneumatically actuated process valve, and the second surface mount component 310 may be a solenoid valve. The solenoid valve 310 operates to receive pressurized air from an inlet 322 and connect it to the second flow path 320, through the face seal 316 and to an inlet 324 of the process valve 306 in order to actuate the valve 306.

[0042] In order to establish the face seal 316, a coupling mechanism 326 is provided. In this example, the mechanism 326 may be a third block 328 that is fixed to the surface X by any

convenient technique such as a bolt 330 for example. Alternatively, the block 328 may be fixed to the first support block 302, or integral with the first support block. In still a further alternative, only the third block 328 may be fixed to the surface X and both the first support block 302 and the second support block 308 moveably coupled thereto to effect the face seal.

[0043] In the embodiment of Fig. 5, a bolt 332 or other suitable mechanism may be used during assembly to join the second support block 308 to the third block 328. As the mechanism 332 is tightened, the second support block 308 is pulled in toward the third block 328, to a point where the face seal 316 is created between the two facing and now closely adjacent surfaces 312, 314. Again, alternatives include but are not limited to having the first support block 302 as the moveable block, or having both support blocks 302, 308 moveable relative to the mechanism 326. In any case, upon final assembly or tightening, a secure face seal is provided and the arrangement 300 is securely connected together. An advantage of this arrangement for providing the face seal is that it avoids a direct mechanical connection between the first and second support blocks 302, 308 thus eliminating issues such as unbalanced loads and torque when multiple face seals are used in more complex arrangements.

[0044] With reference to Figs. 6-9, an exemplary manifold and assembly arrangement

100 is illustrated as an exemplary option for the system 10 of Fig. 1 and also the arrangement depicted in Fig. 5. A substrate, mounting plate or other suitable surface may be provided on which the arrangement 100 may be supported, and is schematically represented by the dashed lines and plane X (illustrated in Figs. 5 and 6 only). The arrangement 100 may be bolted or otherwise affixed to the support surface as will be described herein below.

[0045] The arrangement 100 includes a process valve array 102 and a solenoid valve array 104. The process valve array 102 supports one or more of the process valves 12 _N , however, the devices need not be stream selectors or even pneumatically actuated, though a pneumatic system is the illustrated exemplary embodiment. Each process valve 12 is mounted to a respective support or base block 106 that may be bolted longitudinally together. Alternatively, the blocks 106 may be individually mounted to the surface X, or a single block may be used to support the valves 12 to give two additional alternative examples. Fig. 10 illustrates use of fasteners 108 that securely hold the base blocks 106 together. The process valve array 102 may

also include end blocks 110 and 112. As best viewed in Fig. 10, the base blocks 106 and end blocks 110, 112 include bores 114 that form an air passage that communicates through ports 116 with each of the process valves 12. An inlet 118 may be provided to connect an air line thereto.

[0046] The solenoid array 104 includes a manifold base or side port manifold 120, a mounting bar 122, and a valve and circuit enclosure 124. With additional reference to Fig. 12, the upper surface 126 of the manifold base 120 forms part of the enclosure 124 when the system is fully assembled. The enclosure 124 also may include a removable back cover 128 that is attached to a main housing 130. When fully assembled the housing 130, cover 128 and manifold 120 enclose the array of solenoid valves 16 _N and a circuit board 132 such as may be used to support the control circuit 18 described herein above. The manifold 120 includes a series of ports 134 each of which communicates pressurized air to an inlet of its respective solenoid valve 16 _N mounted on the surface 126. The ports 134 are connected to a pressurized air inlet 136 to the manifold 120. The manifold base 120 further includes ports 135 formed in the valve mount surface 126 each of which communicates with respective outlet port of the associated solenoid valve. Each outlet port 135 is in fluid communication with its respective manifold outlet port 138 through passageways internal the manifold base 120 (see Fig. 14).

[0047] With additional reference to Fig. 13, the manifold 120 further includes side outlet ports 138. There may be a separate outlet port 138 for each solenoid valve 16. When a solenoid valve 16 is energized or pulled-in, pressurized air is provided to the respective outlet 138 by flowing from the inlet 136 and through the actuated valve 16. Fig. 14 illustrates the air passages within the manifold 120. Pressurized air flows into the inlet 136, to a first air passage 140 that communicates with an air inlet of the associated solenoid valve 16 mounted on the manifold surface 126 (valve omitted in Fig. 14). The pressurized air flows through the actuated solenoid valve out to a second air passage 142 to the associated outlet port 138.

[0048] The outlet ports 138 may be provided with a seal recess 144 that retains a suitable seal such as an o-ring 146. The seal 146 provides a face seal against the process valve block 106 as will be further described herein.

[0049] With reference again to Figs. 8, 11 and 12, the mounting bar 122 includes a series of one or more mounting holes 148 that receive fasteners (not shown) that may be used to mount the bar 122 securely to the substrate or mounting plate that supports the process valve array 102. Thus, the mounting bar 122 and the process valve array 102 with the various support blocks 106 are firmly mounted on a support surface in a side by side manner and spatially fixed with respect to each other.

[0050] The manifold base 120 includes a groove 150 that is appropriately sized to receive the mounting bar 122 therein. The mounting bar 122 includes lateral threaded holes 152 that align with lateral threaded holes 154 in the manifold base 120. Bolts 156 or other suitable fasteners are used to join the manifold base 120 to the mounting bar 122. Note that the manifold base 120 is securely mounted to the mounting bar 122 in such a way that its side ported surface 158 (Fig. 13 and Fig. 15) is pressed up against the interface surfaces 160 of the parallel aligned blocks 106 of the process valve array 102. Each such interface surface 160 includes an air inlet port 162 that aligns with a respective outlet port 138 of the manifold base 122. The seals 146 thus seal the port to port communication between the manifold base 122 and the valve blocks 106 by forming face seals against the facing surfaces 160 and 158.

[0051] It will be noted that the manifold base 120 is not mechanically joined to the valve array 102 or the blocks 106 but rather is pressed up against the interface surface 160 of the blocks 106 to form the fluid tight connections for pressurized air to flow from each solenoid valve 16 _N to its associated process valve 12 _N . The mounting bar 122 functions to align the manifold base 120 with the valve array 102 and to provide a support for applying a lateral load between the manifold base 122 and the blocks 106 to effect the face seals. In an alternative configuration, the mounting bar 122 may be omitted and the manifold base 120 bolted directly to the valve array blocks 106. In any configuration, an advantage of not fixing the manifold base to the underlying substrate or mounting plate is that the face seal interface can be readily used without the need for close tolerances because the lateral load is effected by using bolts or other fasteners or pull devices to press the manifold base 120 against the valve array 102. Besides bolts, fasteners and the like, cam type devices and clamping devices may be alternatively used to apply the lateral load between the process valve array 102 and the manifold base 120. The pilot

valves may be self-vented to release the actuation pressure inside the associated process valve when the process valve is closed.

[0052] From Fig. 11 it will be noted that the mounting bar 122 may be provided with a notch 162 that receives a lip 164 on the manifold base 120. This feature may be used to reduce tipping or tilting of the manifold base 120 as it is bolted to the mounting bar 122.

[0053] With reference again to Fig. 13, it should be noted that alternatively the manifold base 120 or side port manifold may also be used as a stand alone or remote controller that supports the pilot valves 16 _N at a location that is distant or remote (as distinguished from closely adjacent as in the exemplary embodiments of Figs. 6-9) from the process valve array 102. In such a case, for example, the outlet ports 138 may include, for example, an NPT threaded port or other connectable port configuration that may accept tubing or tube fittings or other suitable connections to run tubing or hose from the manifold base 120 to various valves. Also, in any embodiment, the manifold base 120 may include additional ports, for example, front and rear ports.

[0054] With reference again to Figs. 8 and 11, associated with each process valve 12 is a proximity sensor 166 each of which has an output coupled to the circuit board for processing as needed by the control circuit 18. The process valves 12 are of the type that have a piston or cap or other moveable member 168 (Fig. 10) that raises and lowers when the valve is opened and closed. A sensor arm 170 is carried by a lid 172 that is attached to the moveable member 168. The sensor arm extends out over its associated proximity sensor 166 so that the proximity sensor produces an output that indicates whether its associated process valve 12 has opened or closed. In an alternative configuration, the proximity sensor may be disposed within its respective pilot valve.

[0055] Thus, the enclosure 124 houses the pilot valves 16, the circuit board 132 and the proximity sensors 166, allowing for a fully self contained valve actuation system that is pneumatically interfaced with the process valve array 102.

[0056] With reference to Figs. 6A and 9A, an alternative to the sensor arm 170 configuration is provided. In this alternative embodiment, the proximity sensors 166 may be mounted on a bracket 200 that is mounted on the enclosure 124 by any suitable means such as screws 202. The bracket 200 may be suitably configured so as to position the sensors 166 so that the sensors can detect movement of the valve members 168. For example, in Fig. 6A the sensors overhang or juxtapose the tops of the process valves 12. A respective wire or signal cable 204 connects each senor output to a corresponding input on the circuit board 132 within the enclosure 124. The sensors 166 are positioned so as to detect movement of their respective valve moveable member 168.

[0057] The invention has been described with reference to the preferred embodiment.

Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.