WO2012145606A2

WO2012145606A2 - Fluid processing systems and sub-systems

Info

Publication number: WO2012145606A2
Application number: PCT/US2012/034420
Authority: WO
Inventors: Charles W. Ii Hayes; Brian G. Deutsch; Douglas A. Nordstrom; Matt DIXON; Michael Gallagher; Scott BASCO; Donald NEGRELLI; Anthony Waters; Glenn A. Evans; James E. Gotch
Original assignee: Swagelok Company
Priority date: 2011-04-20
Filing date: 2012-04-20
Publication date: 2012-10-26
Also published as: WO2012145606A3

Abstract

A fluid processing system includes one or more of a sample probe module for extracting a sample from a process line; a field station module for reducing the pressure of a process gas in a sample transport line; a fast loop module for accelerating the flow of sample media to an analyzer, while allowing for fast, efficient purging of sample transport lines, and minimization of sample waste; a calibration and switching module for preparing properly conditioned samples for selection for insertion into an analyzer; and a fluid distribution header for distribution or collection of utility fluids for use in multiple locations in a fluid processing system.

Description

FLUID PROCESSING SYSTEMS AND SUB-SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority from United States Provisional Application Serial Number 61/477,446, entitled "FLUID PROCESSING SYSTEMS AND SUBSYSTEMS," filed on April 20, 2011, the entire disclosure of which is fully incorporated herein by reference.

TECHNICAL FIELD

[0002] The present application relates to fluid processing systems. More particularly, the application relates to modular sub-assemblies or sub-systems of fluid system components, such as valves, fittings, and filters, that may be used to construct fluid processing systems.

BACKGROUND

[0003] Fluid processing systems, such as systems for use in analyzing samples of a liquid or gas process fluid, may be provided in nearly limitless configurations and dimensions. Such systems are typically constructed using non-dimensional schematic drawings. As a result, two systems constructed to perform identical functions may result in varying performance characteristics, including flow rate, pressure drop, dead space, and sample size, even where the same fluid system components are used, due to variations in fluid component positioning, spacing, and orientation. These variations may affect the content, quality, and predictability of the fluid sample.

SUMMARY

[0004] According to an aspect of one or more of the inventions, a fluid processing system may be constructed from two or more modular sub-systems each pre-engineered to perform one or more functions of the fluid processing system. In an exemplary embodiment, a fluid processing system may include one or more of a sample probe module for extracting a sample from a process line; a field station module for reducing the pressure (and increasing the flow) of a process gas in a sample transport line; a fast loop module for accelerating the flow of sample media to an analyzer, while allowing for fast, efficient purging of sample transport lines, and minimization of sample waste; a calibration and switching module for preparing properly conditioned samples (for example, at appropriate pressure, temperature, flow, and filtration level) for selection for insertion into an analyzer; and a fluid distribution header for distribution or collection of utility fluids for use in multiple locations in a fluid processing system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] These and other inventive aspects and features of the present disclosure will become apparent to one skilled in the art to which the present inventions relate upon consideration of the following description of the exemplary embodiments with reference to the accompanying drawings, in which:

[0006] Figure 1 is a schematic illustration of an exemplary field station module; [0007] Figure 2 is a perspective view of an exemplary field station module; [0008] Figure 3 is a schematic illustration of an exemplary fast loop module; [0009] Figure 4 is a schematic illustration of another exemplary fast loop module; [0010] Figure 5 is a schematic illustration of another exemplary fast loop module; [0011] Figure 6 is a schematic illustration of another exemplary fast loop module; [0012] Figure 7 is a schematic illustration of another exemplary fast loop module; [0013] Figure 8 is a schematic illustration of another exemplary fast loop module; [0014] Figures 9A is a partial perspective view of an exemplary fast loop module; [0015] Figure 9B is another partial perspective view of the fast loop module of Figure 9A; [0016] Figure 9C is a partial exploded view of the fast loop module of Figure 9A; [0017] Figure 1 OA is a schematic illustration of an exemplary valve inlet assembly;

[0018] Figure 1 OB is a perspective view of an exemplary valve inlet assembly;

[0019] Figure 11 A is a schematic illustration of an exemplary valve inlet assembly including a pressure gauge;

[0020] Figure 11B is a perspective view of an exemplary valve inlet assembly including a pressure gauge;

[0021] Figure 12A is a schematic view of an exemplary valve inlet assembly including a filter;

[0022] Figure 12B is a perspective view of an exemplary valve inlet assembly including a filter;

[0023] Figure 13 A is a schematic view of an exemplary valve inlet assembly including a relief valve;

[0024] Figure 13B is a perspective view of an exemplary valve inlet assembly including a relief valve;

[0025] Figure 14A is a schematic view of an exemplary valve inlet assembly including a pressure regulator;

[0026] Figure 14B is a perspective view of an exemplary valve inlet assembly including a pressure regulator;

[0027] Figure 15A is a schematic view of an exemplary valve inlet assembly including a three-way bypass filter and flowmeter;

[0028] Figure 15B is a perspective view of an exemplary valve inlet assembly including a three-way bypass filter and flowmeter;

[0029] Figure 16 is a schematic illustration of an exemplary calibration and switching module; [0030] Figure 17 is a schematic illustration of an exemplary calibration and switching mudule with an upstream regulating valve and flowmeter;

[0031] Figure 18 is a schematic illustration of an exemplary calibration and switching module with an upstream metering valve;

[0032] Figure 19 is a schematic illustration of an exemplary calibration and switching module with a return flow line;

[0033] Figure 20 is a schematic illustration of an exemplary calibration and switching module with a return flow line and an atmospheric reference valve;

[0034] Figure 21 is a schematic illustration of an exemplary calibration and switching module with a bypass line;

[0035] Figure 22 A is a schematic illustration of an exemplary calibration and switching module with a manual override valve assembly, shown in a normal operating condition;

[0036] Figure 22B is a schematic illustration of the calibration and switching module of Figure 22 A, shown with a first calibration inlet assembly in a manual override condition;

[0037] Figure 22C is a schematic illustration of the calibration and switching module of Figure 22A, shown with a second calibration inlet assembly in a manual override condition;

[0038] Figure 23 is a perspective view of an exemplary fluid distribution header;

[0039] Figure 24 is a perspective view of an exemplary body block for an exemplary fluid distribution header;

[0040] Figure 25 is an end view of the body block of Figure 24; and

[0041] Figure 26 is a schematic illustration of an exemplary fluid processing system.

DETAILED DESCRIPTION

[0042] 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, hardware, 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.

[0043] The present application contemplates the pre-engineering of one or more sub-systems of fluid processing components that may be configured to perform one or more functions of a fluid processing system. These functions may include, for example, probe collection of a process fluid sample, delivery of an uncontaminated sample to an analyzer, conditioning the process sample to meet the analyzer's requirements (for example, by verifying and/or adjusting one or more of the fluid's pressure, temperature, flow, and filtration level), and distribution or collection of instrumentation or utility fluids (e.g., nitrogen, cooling water, steam, or compressed air). In one embodiment, a fluid processing sub-system may be provided as a standardized, preassembled module, complete with documentation identifying the performance characteristics of the module. Assembly of a fluid processing system using one or more such modules may result in a variety of benefits, including, for example, standardization of design, predictability of performance, ease of assembly and maintenance, reduced flow path (resulting, for example, in more efficient conditiomng, cleaning, and use of sample fluid), and reduced system footprint.

[0044] In one embodiment, the use of one or more pre-engineered, pre-constructed subsystems or modules to construct a fluid processing system may reduce the amount of end user design, assembly, and resulting performance variations in that portion of the fluid processing system. These pre-engineered sub-systems may additionally be pre-tested to measure a variety of performance characteristics, including, for example, flow rate, pressure drop, dead space, and sample size, thereby eliminating the need for such testing in each assembled system.

[0045] Exemplary systems, sub-systems, assemblies and modules, in accordance with the present application, are described herein.

[0046] SAMPLE PROBE MODULE

[0047] In one embodiment, a module for extracting a sample from a process line may be configured to facilitate extraction of an uncontaminated representative sample from the process line, proper isolation of the process fluid, proper venting of the analytical system pressure, and/or minimization of the analytical system volume for faster sample extraction.

[0048] Accordingly, a sample probe module may be provided with a sample probe extendable into a process line for extraction of a process sample inward of an outer wall of the process line, to minimize the extraction of impurities that collect on the internal surfaces of the process line pipe. While the probe may be secured in place (for example, by welding), in other embodiments, the probe may be insertable and retractable through the module body, to allow for removal, cleaning, and maintenance of the probe without shutting down the process system.

[0049] The sample probe module may additionally be provided with a block valve for controlled flow of a sample of the process fluid to supply to an analyzer, and a bleed valve for depressurizing the sample line when the block valve is closed. The block and bleed valves may be interlocked such that the bleed valve is secured in a closed position when the block valve is open, and the block valve is secured in a closed position when the bleed valve is open, thereby preventing continuous flow from the process line through the bleed valve. The block valve may also be interlocked with a probe blocking device (e.g., a valve), such that the block valve may not be closed onto an inserted probe (which could damage the block valve or the probe), and such that the probe blocking device may not be operated to allow insertion of a probe against a closed valve (which could also damage the block valve or the probe). Exemplary embodiments of sample probe modules are described in co-pending PCT Application Serial No. PCT/US11/36238, entitled "PROCESS INTERFACE VALVE ASSEMBLY" and filed on April 15, 2011, the entire disclosure of which is incorporated herein by reference. Other features and embodiments of exemplary sample probe modules are described and shown in the "Sample Probe Module Application Guide," Swagelok Co., March 2011, the entire disclosure of which is incorporated herein by reference.

[0050] FIELD STATION MODULE

[0051] In another embodiment, a module may be configured to reduce the pressure of an extracted process gas sample before transporting the sample to an analyzer, thereby reducing the density of gas molecules within the sample. This increases the flow velocity of the sample and reduces the time necessary to purge the process gas from the sample line prior to obtaining a new sample. The pressure reducing module, or "field station module," may include a process isolation valve for controlling flow into the module, a pressure regulator for reducing the pressure of the extracted gas sample, a filter between the isolation valve and the pressure regulator to prevent exposure of the pressure regulator to contaminants, and optionally, a relief valve to protect portions of the analytical system downstream of the field station module from over-pressurization, for example, due to failure of the pressure regulator. Pressure indicators may be provided upstream of the filter, between the filter and the pressure regulator, and/or downstream of the pressure regulator, to monitor the performance of the module.

[0052] Figure 1 illustrates a schematic diagram of an exemplary field station module 10 having an inlet port 10a, an outlet port 10b, and a pressure regulator 11 configured to reduce the pressure of gas (e.g., process gas) flowing through the module 10, for example, to increase the gas flow rate. First and second pressure indicators (e.g., pressure gauges) 12, 13 may be installed upstream and downstream of the pressure regulator 11 to measure a pressure drop across the regulator, for example, to ensure proper regulator function. A shutoff valve 14 (e.g., a ball valve) may be installed at the inlet port 10a, for example, to allow for selective local shutoff of the flow through the field station module 10.

[0053] A filter 15 may also be installed upstream from the pressure regulator 11 to reduce contamination and/or moisture in the process fluid, for example, to avoid contamination of the pressure regulator 11 or to provide a clean and/or dry process fluid for sampling and analysis. For example, depending on the particulate load in the process line, a small-capacity particle filter may be used for a relatively clean process line, and a large capacity particle filter may be used for a high particulate load process line. As another example, a filter- membrane separator may be used for process lines with low levels of moisture and particle load. As still another example, a coalescing filter (which may include a membrane saparator) may be used for high moisture process lines, with collected moisture being releasable through a drain port 10c. Additionally or alternatively, a heater 16 may be installed on the module 10 to prevent or limit condensation within the sample transport line, particularly where both condensation and particulate are a substantial concern. Additionally, a third pressure indicator 17 may be installed upstream of the filter 15, to allow for pressure drop measurements across the filter 15, for example, to determine whether filter maintenance or replacement is needed (as evidenced by an excessive increase in pressure drop).

[0054] Still further, an optional relief valve 18 (for example, a proportional relief valve), connected to a vent port lOd, may be installed downstream from the regulator 11 to protect downstream analytical systems from drastic increases in system pressure that occur too rapidly for the pressure regulator 11 to effectively regulate the excessive system pressure.

[0055] While a field station module may be installed at many locations within a sample transport line, a field station module may be positioned directly adjacent or in close proximity to an extraction point on a process line (e.g., coupled directly to or proximate to a sample probe module, as described above), for example, to minimize high pressure (and slower flowing) sections of process line. As a result, the field station module may be installed at difficult-to-reach locations that are often exposed to harsh outdoor environments. According to an aspect of the present application, a field station module includes a protective enclosure that is easily moved to access the instruments and controls of the enclosure, while remaining secured to the enclosure, such that the operator does not need to hold or stow the enclosure while operating or examining the module. In one example a clam-shell type enclosure is provided, with a rear wall that is rigidly secured behind a rear portion of the module, and a hinged cover including front, top, and side walls providing protection for and/or insulation of the module components. Examples of such enclosures include ABS plastic VTPAK enclosures manufactured by O'Brien Corporation, and fiberglass DIABOX enclosures manufactured by Intertec Instrumentation.

[0056] In another embodiment, a process fluid system module (e.g., a field station module, as described above) includes a base frame and an enclosure liftable with respect to the base frame to provide 360 degree access to the module components from an entire perimeter of the module. In one such embodiment, the enclosure is securable in a raised position, such that the operator may use both hands to manipulate the instruments and controls of the module.

[0057] Figure 2 illustrates a field station module 20 having a base frame 21 including a lower base 22 and upward extending side rails 23, which may, but need not, support one or more of the instrumentation components of the module. An enclosure 24 in sliding engagement with the side rails 23 is releasably secured to the base 22 by a latch member 25 when the enclosure 24 is in a lowered or closed position. When the latch member 25 is disengaged from the base 22, the enclosure 24 may be lifted to a raised or open position to access the module components. To facilitate lifting of the enclosure 24, the enclosure may be connected with the base frame 21 by an upward biasing mechanism 26, such as, for example, a force assist gas spring, which may provide sufficient force to hold the enclosure 24 in the raised position until the enclosure is manually lowered by the user against the biasing force. In another embodiment, the enclosure may include a second latch member 27 configured to releasably engage the base frame when the enclosure is in the raised position. In still another embodiment, the enclosure may be detachable from the upward biasing mechanism to permit removal of the enclosure from the base frame. One or more handles 28 may be provided on the enclosure 24 to facilitate lifting and/or removal of the enclosure 24. The enclosure may further include a window portion 29 to permit viewing of the internal module components (e.g., pressure gauges, valve handles) when the enclosure is in the lowered position [0058] Additional exemplary features and embodiments of field station modules are described and shown in the "Field Station Module Application Guide," Swagelok Co., March 2011, the entire disclosure of which is incorporated herein by reference.

[0059] FAST LOOP MODULE

[0060] In another embodiment, a module may be constructed from fluid system components configured to quickly move sample media to an analyzer, while allowing for fast, efficient purging of sample transport lines, and minimization of sample waste. This "fast loop" module provides for two conditions, a sampling condition in which process fluid is delivered through the fast loop to the analyzer, and a bypass condition in which the fast loop is bypassed (for example, when the analyzer is not in service. To provide a range of functionality, the fast loop module may optionally also include one or more of: a filter for preparing a sample for analysis; a flowmeter for monitoring the flow rate through the fast loop, a regulating valve (for example, a needle valve) for controlling the flow rate, a pressure gauge for monitoring fluid pressure within the module; a grab sample outlet for selectively extracting a sample of the process fluid (for example, for testing outside of the analyzer); a relief outlet for protecting the fast loop and analyzer fluid components from excess pressure; a return line for returning analyzed sample flow to the fast loop module; a switch drain for diverting a sample returned from the analyzer to a drain; and a purge line for purging the process fluid from the fast loop fluid components (for example, using an inert gas or solvent).

[0061] In a first configuration, as shown in the schematic view of Figure 3, an exemplary fast loop module 30 includes inlet and outlet switching or bypass valves 31, 32 (for example, ball valves) operable between a bypass position providing between the inlet and outlet ports 30a, 30b of the fast loop when the downstream analyzer is not in service, and a sampling position in which the process fluid is delivered downstream from the fast loop module to an analyzer (not shown) from an analyzer port 30c. The sampling line includes a filter 33 (for example, a centrifugal or vortex-style filter) to the analyzer, with a flowmeter 34 and a flow regulating valve 35 (for example, a needle valve) for monitoring and controlling flow through the fast loop. The regulating valve 35 may be provided upstream of the flowmeter 34 for a gas system and downstream of the flowmeter 34 for a liquid system. A pressure gauge 36 may be provided on the bypass side of the fast loop filter to eliminate the effect of a deadleg, with an optional sintered snubber 36a to dampen any response to pressure pulses. As shown, the two switching valves 31, 32 may be configured for operation by a single handle 37 coupling the two valves such that the valves are simultaneously operated between the sampling position and the bypass position. The flow path in each valve 31, 32 may be sized and configured to include an intermediate or transitional position during actuation in which the bottom or common port 31a, 32a is open to both side or switching ports 31b, 31c, 32b, 32c, such that flow is never completely shut off at the fast loop module during actuation. This ensures collection of a fresh sample, and eliminates the water hammer effect of extreme pressure spikes resulting from closing a valve in a high-flow liquid line, which can damage system components. The use of valves configured to switch from bypass to sampling by only 90 degree rotation of the valve handle (using for example, ball valves with "XL" drill configurations, having an "L" shaped horizontal drilling, for connecting with one of the valve switching ports, intersecting a vertical drilling for connecting with the valve common port) can further minimize or eliminate any complete shutoff position during rotation of the handle.

[0062] According to another aspect of the present application, a lockout bracket may be assembled with the module to secure the valve handle in either of the bypass and sampling positions. In the exemplary embodiment of Figures 9A, 9B, and 9C, first and second lockout brackets 137a, 137b may be assembled with the module 130 to selectively secure a handle 137 operating inlet and outlet bypass valves 131, 132 in the sampling and bypass positions, respectively. While any type of lockout bracket or other locking mechanism may be utilized, in an exemplary embodiment, the lockout brackets 137a, 137b each include a locking plate pivotably connected to a base plate (e.g., by a rivet or other fastener) and securable in a position blocking actuation of the handle 137 by a padlock (not shown) secured through an aperture in the locking plate.

[0063] In one embodiment, the bypass valve handle may be removable without removing the bypass valves from the assembly, for example, to make packing adjustments to the valves or other such maintenance.

[0064] In a second configuration, as shown in the schematic view of Figure 4, a return line 30c may optionally be provided to receive analyzed process fluid from an analyzer for return to the process line (for example, upstream of the outlet bypass valve and downstream of the flow control valve, to minimize pressure differential). The return line may be provided with a check valve 41 to prevent backflow to the analyzer. [0065] In a third configuration, as shown in the schematic view of Figure 5, a switch drain may additionally be provided to divert a sample returned from the analyzer to a drain 30e, for example, to depressurize the analyzer so that the complete sample flow path may be purged or flushed during maintenance. In the illustrated embodiment, a switching drain valve 42 is operable between a process position, in which the analyzed fluid in the return line 30d is directed to the outlet bypass valve 32, and a drain position in which the analyzed fluid in the return line is directed to a vent or drain line 30e.

[0066] As shown in the exemplary embodiment of Figures 9A, 9B, and 9C, the drain valve handle 143 may be interlocked with the bypass valve handle 137, such that when the bypass valves 131, 132 are in the sampling position, the drain valve handle 143 is blocked from movement to the drain position, and when the drain valve 142 is in the drain position, the bypass valve handle 137 is blocked from movement to the sampling position. This arrangement prevents accidental continued draining of the process fluid during sampling. In the illustrated example, the bypass valve handle 137 includes a plate member 137c that is received in a corresponding notch 143c in the drain valve handle 143 when the bypass valves 131, 132 are in the sampling position and the drain valve 142 is in the process position. Engagement between the plate member 137c and the notch 143c prevents rotation of the drain valve handle 143. When the bypass valves 131, 132 are in the bypass position and the drain valve 142 is in the drain position, an edge of the plate member 137c engages an outer periphery of the base of the drain valve handle 143 to prevent rotation of the bypass valve handle 137.

[0067] As shown in Figures 5-8, in addition to a switching drain valve 42, a shutoff valve 44 (for example, a plug valve) to the drain may be provided between the filter and the flow control valve to facilitate drainage of the remainder of the fast loop. A check valve 45 may be added to prevent backflow from the vent. The drain connections may be placed at the lowest points on the system to allow gravity to assist in draining.

[0068] In a fourth configuration, as shown in the schematic view of Figure 6, a purge line 30f may optionally be provided to supply a purge gas (e.g., an inert gas) or liquid (e.g., a solvent) to the fast loop to purge the process fluid from the flowmeter 34, filter 33, and other fast loop module components. As shown, the purge line 30f may be provided with a purge valve 46 to allow purge fluid flow from the purge line 3 Of to the process line upstream of the filter 33. The purge valve 46 may be operatively connected with a drain valve 42 (for example, by ganged handles or a single handle operating both valves), such that the purge valve and drain valve are either (a) in the open and drain conditions, respectively, or (b) in the closed and process conditions, respectively. A regulating valve 47 (e.g., a needle valve) and check valve 48 may be used to regulate purge fluid and prevent backflow.

[0069] In the exemplary embodiment of Figures 9A, 9B, and 9C, a purge valve 146 includes a geared hub 146a that meshes with a corresponding geared hub 142a of the drain valve 142 (see Figure 9C) for simultaneous operation of the purge and drain valves 146, 142. By combining this linking handle 143 with the valve interlock described in the third configuration above, the purge valve 146 is prevented from being in a purge condition when the bypass valves 131, 132 are in the sampling position, thereby preventing contamination of the process fluid with the purge fluid. In the illustrated example, the drain valve handle is rotationally aligned with the purge valve 146 and rotationally offset from the drain valve 142. In another embodiment, in which a purge valve is not required, the purge valve may be replaced with a rotation displacing shaft (not shown), similarly connected to the drain valve (for example, by a geared hub connection), allowing the drain valve to remain in a uniform position in the module. In still another embodiment (not shown), a drain valve handle may be rotationally aligned with the drain valve and rotationally offset from the purge valve. In an exemplary embodiment, the linking valve handle and coupling arrangement may be removable without removing the drain valve and purge valve from the assembly, for example, to make packing adjustments to the valves or other such maintenance.

[0070] In a fifth configuration, as shown in the schematic view of Figure 7, the shutoff valve 42 to the drain 30e may be an automatic pneumatically actuated valve driven by the purge gas, such that operation of the purge valve 46 automatically operates the remote shutoff drain valve 42 to facilitate simultaneous drainage and purging of the fast loop components. As shown, an additional fitting 49a may be used to vent the actuation line, and a check valve 49b may be added to prevent backflow of process fluid into the shutoff drain valve actuator.

[0071] Other features may be provided in any one or more of the exemplary fast loop modules. For example, as shown in the schematic view of Figure 8, a relief outlet 30g controlled by a relief valve 38 may optionally be provided upstream of the inlet bypass valve 31, for example, to protect the fast loop components from spikes in system pressure. Additionally, a grab sample outlet 3 Oh controlled by a shutoff valve 39 (for example, a needle valve) may optionally be provided downstream of the outlet bypass valve 32, for example, to allow a user to extract a sample of the process fluid (e.g., into a sample cylinder) for testing or analysis outside of the analyzer.

[0072] Additional exemplary features and embodiments of fast loop modules are described and shown in the "Fast Loop Module Application Guide," Swagelok Co., March 2011, and the "Fast Loop Module User's Manual," Swagelok Co., April 2011, the entire disclosures of which are incorporated herein by reference.

[0073] CALIBRATION AND SWITCHING MODULE

[0074] In another embodiment, a module may be constructed from fluid system components configured to prepare properly conditioned samples (for example, at appropriate pressure, temperature, flow, and filtration level) for selection for insertion into an analyzer. In one embodiment, a calibration and switching module is configured to provide switching between one or more sample streams (for example, 1-10 sample streams) and optionally introduction of one or more calibration fluids (for example, up to two calibration fluids). The calibration and switching module may be installed in a fluid processing system downstream of one or more fast loop modules (e.g., one or more of the exemplary fast loop modules described herein) and upstream of an analyzer. In one embodiment, a double block and bleed assembly (for example, a double block and bleed stream selector valve or SSV assembly) is utilized in place of the three-way valve utilized by conventional systems to introduce calibration fluid to the analyzer, to prevent intermixing of sample and calibration fluids.

[0075] As different samples require different types or degrees of conditioning, the calibration and switching module may be constructed using one or more modular components combined to produce one or more inlet assembly configurations. These inlet assemblies may be provided in a modular format, for example, using modular platform components (MPC), examples of which are described in "Modular Platform Components (MPC): Surface-Mount Components, Substrates, Manifolds, Mounting Components, and Assembly Hardware," Swagelok Co., September 2010, the entire disclosure of which is incorporated herein by reference. [0076] In an exemplary first inlet assembly configuration, or valve inlet assembly 50a, as shown in the schematic and perspective views of Figures 10A and 10B, a shutoff valve 51a (for example, a ball valve, such as a Swagelok 42T series ball valve) in series with a double block and bleed stream selector valve (e.g., a Swagelok SSV assembly) 52a. Exemplary SSV assemblies are described in "Stream Selector System for Process Analyzer Applications," Swagelok Co., March 2009, the entire disclosure of which is incorporated herein by reference. The SSV assembly 52a provides for introduction of the calibration fluid, and may be connected with SSV assemblies of other inlet assemblies to provide a common vent.

[0077] In an exemplary second inlet assembly configuration, or gauge inlet assembly 50b, as shown in the schematic and perspective views of Figures 11A and 11B, an inlet pressure gauge 53b (e.g., a Swagelok M-series pressure gauge) is added to the first inlet assembly configuration, for example, to monitor fluid pressure entering the assembly, for example, from a fast loop module (e.g., one of the exemplary fast loop modules described herein).

[0078] In an exemplary third inlet assembly configuration, or filter inlet assembly 50c, as shown in the schematic and perspective views of Figures 12A and 12B, a filter 54c (e.g., a Swagelok TF particle filter having an element pore size of 0.5 μπι, 2 μηι, or 7 μιη) is added to the second inlet assembly configuration, for example, to provide additional protection of the analyzer from contamination.

[0079] In an exemplary fourth inlet assembly configuration, or relief inlet assembly 50d, as shown in the schematic and perspective views of Figures 13A and 13B, a relief valve 55d (e.g., a Swagelok KVV relief valve) is added to the third inlet assembly configuration, for example, to protect the sample system from pressure surges.

[0080] In an exemplary fifth inlet assembly configuration, or pressure regulator inlet assembly 50e, as shown in the schematic and perspective views of Figures 14A and 14B, a pressure regulator 56e is added to the fourth inlet assembly configuration, for example, to allow for pressure equalization of multiple streams in multiple inlet assembly configurations before they are switched. Such a configuration may be utilized, for example, in a system that does not include a field station module, as described in greater detail above.

[0081] In an exemplary sixth inlet assembly configuration, or flow loop inlet assembly 50f, as shown in the schematic and perspective views of Figures 15A and 15B, a three-way bypass filter 57f enables flow to continue through a flow loop (past relief valve 55f, pressure gauge 53f, flowmeter 58f, and shutoff valve 59f) for return to the process line when the SSV assembly 52f is closed.

[0082] Additional inlet assembly configurations may be generated using any combination or sub-combination of the above described components, as desired to provide a desired level and type of conditioning of the sample streams.

[0083] A combination of two or more inlet assembly configurations may be provided in a single calibration and switching module, and may be provided with a single outlet line for connection with an analyzer, using one or more of an outlet fitting, a flowmeter and flow control valve upstream of the analyzer, a metering valve upstream of the analyzer, a flow meter and flow control valve downstream of the analyzer, and an atmospheric reference valve (to bring a gas sample to atmospheric pressure before injection into a discontinuous analyzer). One or more inlet assemblies may be provided for control and conditioning of sample streams, and one or more inlet assemblies may be provided for control and conditioning of calibration fluids.

[0084] Figures 16 - 22C schematically illustrate exemplary calibration and switching modules 200a-g having three sample inlet assemblies 50e and two calibration inlet assemblies 50c with SSV's 52e, 52c connected in series to provide a common outlet for the samples and calibration fluids. As shown in the exemplary module 200a of Figure 16, where flow control and measurement are not needed (e.g., when performed outside of the module), a simple outlet port or fitting may be connected with the common outlet 201a to deliver a selected sample/calibration fluid to the analyzer. To control and measure flow at the module outlet, as shown in the exemplary module 200b of Figure 17, a regulating valve 202b (e.g., a needle valve) and flowmeter 203b (e.g., a glass or metal tube flowmeter) may be assembled with the common outlet 201b. Where flow measurement is not required, a metering valve 204c may be assembled with the common outlet 201c of the module 200c, as shown in Figure 18.

[0085] A calibration and switching module may also include components for receiving and recovering return flow of sample fluid from the analyzer. As shown in Figure 19, a return inlet 205d of a calibration and switching module 200d includes a regulating valve 206d (e.g., a needle valve) and flowmeter 207d (e.g., a glass or metal tube flowmeter) to control and measure flow from the analyzer outlet, a pressure gauge 208d to indicate pressure at the analyzer outlet, and a check valve 209d to protect against backflow. As shown, this return line may be separate from the inlet assemblies. In another embodiment, as shown in Figure 20, a return inlet 205 e may be assembled with an SSV block and bleed assembly 210e assembled with the series of SSV's 52e, 52c to discharge return fluid to the common vent or pass the return fluid to a separated vent or flare, for example, through a check valve 227e.

[0086] Additionally, as shown in Figure 20, a calibration and switching module 200e may be provided with an atmospheric reference valve (ARV) 21 le including an SSV block and bleed assembly 212e assembled with the series of SSV's 52e, 52c to receive a selected sample/calibration fluid for delivery to the analyzer, and a connected vent passage to discharge fluid to the common vent. A metering valve 213e allows the flow of sample fluid to be reduced and thereby brought to atmospheric pressure before delivery to the analyzer.

[0087] Further, an additional assembly (for example, an assembly including an SSV, a gauge, and a flowmeter) may be utilized to bypass some of the sample flow to a common vent connection for disposal or return to the process line, for example, to increase process fluid flow through the calibration and switching module to the analyzer. The SSV may be configured such that the bypass flow is automatically shut off during a calibration operation to prevent the loss of calibration fluid.

[0088] Figure 21 schematically illustrates an exemplary calibration and switching module 200f including a bypass SSV 214f assembled with the series of SSV's 52e. 52c. The bypass SSV 214f is held in a normally open position to deliver unused sample fluid to a bypass line, for disposal or return to the process line. The exemplary bypass SSV 214f is connected to a regulating valve 215f, flowmeter 216f, pressure gauge 217f, and check valve 218f, to control and measure flow through the bypass line to a bypass outlet. The exemplary bypass SSV 214f is pneumatically actuated by pressurized gas supplied through a switching valve 219f. When a calibration inlet assembly is operated by supplying pressurized gas to the corresponding SSV 52c, this pressurized gas is also connected with an actuator for the switching valve 219f, to move the switching valve to a venting condition, causing the bypass SSV 214f to revert to a closed position, to conserve calibration fluid. A shuttle valve 228 f may be utilized to facilitate proper application of pressurized air to the actuator of the switching valve 219f. [0089] Still further, a calibration and switching module may be configured for manual calibration, allowing operators to override pneumatic pressure signals and select the appropriate SSV assembly for calibration at a desired time. To provide a manual override of a timed or automatic calibration process, a manual valve may be provided with two flow paths, with a first flow path connecting the actuation port of the air actuated SSV with an input line for an automatic pneumatic actuation signal when the valve is in a normal position, and a second flow path connecting the actuation port of the air actuated SSV to a pressurized pneumatic line when the valve is in an override position. To manually force a calibration of the system, the valve is operated from the normal position to the override position.

[0090] Figure 22A, 22B, and 22C schematically illustrate an exemplary calibration and switching module 200g including a manual calibration assembly 220g for a calibration and switching module 200g having two calibration inlet assemblies 50c. The manual calibration assembly 220g includes first and second automatic actuation ports 22 lg, 222g for delivering pressurized gas to the SSV's 52c of the first and second calibration inlet assemblies 50c, a manual actuation port 223g for delivering pressurized gas to a user selected one of the first and second calibration inlet assemblies 50g, and an actuation gas return port 224g for diverting or returning unused pressurized gas. The manual calibration assembly includes first and second override valves 225g, 226g. The first override valve 225g is operable to divert pneumatic actuation signals from the first automatic actuator port 22 lg to the actuation gas return port 224g while directing pneumatic pressure from the manual actuation port 223g to the SSV 52c of the first calibration inlet assembly 50c. The second override valve 226g is operable to divert pneumatic actuation signals from the second automatic actuator port 222g to the actuation gas return port 224g while directing pneumatic pressure from the manual actuation port 223g to the SSV 52c of the second calibration inlet assembly 50c. While many different manual override valve configurations may be utilized, in an exemplary embodiment, the first and second manual override valves 225 g, 226g include four-ported ball valves with "Y" style drilling configurations (two non-intersecting "L" shaped horizontal drillings), operable to connect each port with one of two adjacent ports.

[0091] In the illustrated embodiment, as shown in Figure 22 A, when both of the override valves 225g, 226g are in normal positions, pneumatic signals to the first automatic actuator port 221g are directed through the first manual override valve 225g to the SSV 52c of the first calibration inlet assembly 50c, pneumatic signals to the second automatic actuator port 222g are directed through the second manual override valve 226g to the SSV 52c of the second calibration inlet assembly 50c, and pneumatic pressure to the manual actuation port 223g is directed through both of the first and second manual override valves 225g, 226g to the actuation gas return port 224g. When the first override valve 225 g is in the override position and the second override valve 226g is in the normal position (Figure 22B), pneumatic signals to the first automatic actuator port 22 lg are directed through both of the first and second manual override valves 225 g, 226g to the actuation gas return port 224g, pneumatic signals to the second automatic actuator port 222g are directed through the second manual override valve 226g to the SSV 52c of the second calibration inlet assembly 50c, and pneumatic pressure to the manual actuation port 223 g is directed through the first manual override valve 225g to the SSV 52c of the first calibration inlet assembly 50c. When the first override valve 225g is in the normal position and the second override valve 226g is in the override position (Figure 22C), pneumatic signals to the first automatic actuator port 22 lg are directed through the first manual override valve 225g to the SSV 52c of the first calibration inlet assembly 50c, pneumatic signals to the second automatic actuator port 222g are directed through the second manual override valve 226g to the actuation gas return port 224g, and pneumatic pressure to the manual actuation port 223 g is directed through both of the first and second manual override valves 225 g, 226g to the SSV 52c of the second calibration inlet assembly 50c. In an exemplary embodiment (not shown), a manual calibration assembly may be provided with an override valve handle interlock configured to prevent both override valves from being in the override position at the same time.

[0092] To aid in identifying each of the assemblies within a calibration and switching module, visual identifiers may be secured to each assembly. As one example, a lockdown bar securing the inlet fitting to the assembly may be color coded for easy visual identification of the types of assemblies included on the module. For example, a first color (blue) may designate a process sample inlet assembly, a second color (orange) may designate a calibration assembly, a third color (green) may designate a bypass assembly, and a fourth color (white) may designate an analyzer assembly. As another example, each modular component within each assembly may be further identified by a label or tag, such as, for example, a tag secured to a mounting fastener.

[0093] Additional exemplary features and embodiments of calibration and switching modules are described and shown in the "Calibration and Switching Module Application Guide," Swagelok Co., March 2011, the entire disclosure of which is incorporated herein by reference.

[0094] FLUID DISTRIBUTION HEADER

[0095] In another embodiment, a module may be configured to distribute or combine fluids for use in multiple locations in a fluid processing system. As one example, a fluid distribution header module may be connected to a utility fluid source (for example, cooling water, steam, compressed air, or plant nitrogen) for selective branched distribution of the utility fluid to multiple subsystems. As another example, the branches of a fluid distribution header may each be connected to a fluid source (e.g., a drain) for collection and disposition or disposal of the combined fluid. In one embodiment, a fluid distribution header includes an inlet having a shutoff valve, multiple outlets each having its own isolation valve, and a drain outlet having an optional shutoff valve. Various features may be utilized to enhance the performance of the fluid distribution header, including, for example, a header body with squared off sides that mount solidly and prevent twisting, and a selectable number of branch outlets (e.g., 2-16 outlets).

[0096] Figure 23 illustrates a perspective view of an exemplary fluid distribution header 60 having a body block 61 provided with a common end port 62 and two or more branch ports 63a-h extending from one or more sides of the body block. As shown, the common port and end ports may be provided with shutoff valves 64, 65a-h, for example, by threaded or welded engagement with the body block 61. The common port 62 may function as either an inlet (for distribution) or as an outlet (for collection). Additionally, the body block 61 may be provided with a second common or end port 66 (which may include a shutoff valve 76), such that the fluid distribution header 60 includes both inlet and outlet common ports, for example, to permit assembly of multiple distribution headers in series. A pressure gauge 71 may also be installed in the body block 61 to facilitate monitoring of fluid pressure within the fluid distribution header 60.

[0097] While the distribution header body block may be provided in many different shapes or configurations, in the illustrated embodiment, as shown in Figures 24 and 25, the body block 61 is provided from an extrusion having a cylindrical bore 66a extending between cylindrical pipe ends 67 (for example, to accommodate welding to a valve, tube fitting, or tube adapter, or for machining a pipe thread connection). The main body portion of the body block 61 includes at least one elongated, raised, and substantially flat hub 68, with one or more branch bores 66b disposed in the hub to intersect the central bore 66a. In the illustrated embodiment, four raised hub portions are separated by thinner cylindrical wall sectors 69. The flat raised hub portions 68 provide additional wall thickness and a flat, non-rounded surface for facilitating machining of threaded ports and/or welding of port connections. Further, the non- cylindrical cross-sectional shape of the body block 61 facilitates bracket-mounting of the body block to a structure and installation of connections to the ends 67 without excessive twisting of the mounted block 61.

[0098] Additional exemplary features and embodiments of fluid distribution headers are described and shown in the "Fluid Distribution Header Application Guide," Swagelok Co., March 2011, a copy of which is included in the attached Appendix.

[0099] EXEMPLARY FLUID PROCESSING SYSTEM

[00100] Figure 26 schematically illustrates an exemplary fluid processing system 500 for collecting and analyzing fluid samples from a process line P. A sample probe module 505 (e.g., the exemplary sample probe modules described above and in the previously incorporated co-pending PCT Application Serial No. PCT/US 11/36238) is assembled to the process line for extracting an adequate sample from the process line. Where the process fluid is a gas, a field station module 510 (e.g., the exemplary field station modules described above) is optionally assembled on or proximate to the sample probe module to reduce the pressure and increase the flow rate of the extracted sample. The sample is delivered to the analyzer location 501 by a sample transport line, which may be connected to a fast loop module 530 for return of bypassed sample flow to the process line through a return tap 508. The fast loop module 530 delivers the sample fluid to a sample inlet assembly of a calibration switching module 550 which transmits the sample to an analyzer 590 (e.g., gas chromatograph) for analysis. The analyzer 590 and calibration and switching module 550 may optionally return sample fluid to the fast loop module 530 for return to the process line. Additionally, fluid distribution headers 560a, 560b may deliver utility fluids to (e.g., pressurized air for pneumatically actuated valves) or collect fluids from (e.g., pressurized air to be vented, process fluid to be drained) the analyzer location 501. [00101] Additional exemplary features and embodiments of fluid distribution headers are described and shown in the "Fluid Distribution Header Application Guide," Swagelok Co., March 2011, a copy of which is included in the attached Appendix.

[00102] The invention has been described with reference to several exemplary embodiments. Modifications and alterations will occur to others upon a reading and understanding of this specification.

Claims

We claim:

1. A fluid processing system comprising: a sample probe module assembled to a process line for extracting a sample from the process line; and a fast loop module in fluid communication with the sample probe module, the fast loop module comprising: an inlet bypass valve having a common port connected to a sample inlet, a first switching port connected to an analyzer supply line, and a second switching port connected to a bypass line; an outlet bypass valve having a common port connected to a sample outlet, a first switching port connected to the analyzer supply line, and a second switching port connected to the bypass line; and a bypass valve actuator operatively connected to each of the inlet and outlet bypass valves, and operable between a first position in which the common ports of the inlet and outlet bypass valves are open to the analyzer supply line, and a second position in which the common ports of the inlet and outlet bypass valves are open to the bypass line.

2. The fluid processing system of claim 1, wherein the valve actuator comprises a pivotable handle.

3. The fluid processing system of claim 1, further comprising a locking bracket for securing the pivotable handle in one of the first and second positions.

4. The fluid processing system of claim 1, wherein the inlet and outlet bypass valves are configured such that the common ports of the inlet and outlet bypass valves are open to at least one of the analyzer supply line and the bypass line at any intermediate position between the first and second positions.

5. The fluid processing system of claim 1, further comprising an analyzer return line and a drain valve connected to the analyzer return line for delivering returned fluid to the bypass line in a first switching position and for delivering returned fluid to a drain in a second switching position.

6. The fluid processing system of claim 5, wherein the drain valve includes an actuation handle configured to block movement of the bypass valve actuator from the second position to the first position when the drain valve is in the second switching position.

7. The fluid processing system of claim 5, wherein the drain valve includes an actuation handle, and the bypass valve actuator blocks movement of the actuation handle from the first switching position to the second switching position when the bypass valve actuator is in the first position.

8. The fluid processing system of claim 5, further comprising a purge line connected with the analyzer supply line by a purge valve movable between an open position and a closed position.

9. The fluid processing system of claim 8, further comprising an actuation handle operatively connected to each of the drain valve and the purge valve, and operable between a first position in which the purge valve is in the closed position and the drain valve is in the first switching position, and a second position in which the purge valve is in the open position and the drain valve is in the second switching position.

10. The fluid processing system of claim 1, further comprising a calibration and switching module comprising: at least one sample inlet assembly in fluid communication with the fast loop module and comprising a double block and bleed stream selection valve operable between an open position for supplying a sample fluid from the fast loop module to an outlet flow loop and a closed position for venting an internal sample fluid volume to a common vent; and at least one calibration inlet assembly comprising a double block and bleed stream selection valve operable between an open position for supplying a calibration fluid to the outlet flow loop and a closed position for venting an internal calibration fluid volume to the common vent.

11. The fluid processing system of claim 10, wherein the stream selection valve of the at least one calibration inlet assembly is connected with an automatic air inlet line for automatically supplying a pneumatic signal to actuate the stream selection valve of the at least one calibration inlet assembly from the closed position to the open position.

12. The fluid processing system module of claim 11, wherein the calibration and switching module further comprises a manual override valve operable for selectively connecting the automatic air inlet line with an air return line and connecting a second air inlet line with the stream selection valve of the at least one calibration inlet assembly to selectively open the stream selection valve of the at least one calibration inlet assembly.

13. The fluid processing system of claim 10, wherein the at least one calibration inlet assembly comprises first and second calibration inlet assemblies.

14. The fluid processing system of claim 13, wherein the stream selection valves of the first and second calibration inlet assemblies are connected with corresponding first and second automatic air inlet lines for automatically supplying a pneumatic signal to actuate the stream selection valves of the first and second calibration inlet assemblies from the closed position to the open position.

15. The fluid processing system of claim 14, wherein the calibration and switching module further comprises first and manual override valves each operable for selectively connecting the corresponding first and second automatic air inlet lines with an air return line and connecting a third air inlet line with the stream selection valve of the corresponding one of the first and second calibration inlet assembly to selectively open the stream selection valve of the at least one calibration inlet assembly.

16. The fluid processing system of claim 1, further comprising a field station module disposed between and in fluid communication with the sample probe module and the fast loop module, the field station module comprising: a base member; an inlet port connected with the sample probe module and an outlet port connected with the fast loop module, the inlet and outlet ports extending through the base member; and a pressure reducing arrangement including a pressure regulator supported by the base member and in fluid communication with the inlet and outlet ports.

17. The fluid processing system of claim 16, wherein the field station module further comprises first and second side rails extending from the base member and an enclosure slideable on the side rails between a lowered position covering the base member and a raised position supported by the side rails and providing access to the pressure reducing arrangement from an entire perimeter of the base member.

18. The fluid processing system of claim 17, wherein the field station module further comprises a force-assisted gas spring mechanism to facilitate lifting the enclosure to the raised position.

19. The fluid processing system of claim 18, wherein the enclosure is disengageable from the gas spring mechanism to remove the enclosure from the field station module.

20. The fluid processing system of claim 1, further comprising a fluid distribution header for delivering a utility fluid to or from the fluid processing system, the fluid distribution header comprising: a body block including a cylindrical internal bore opening to a common end port, the body block including at least one elongated raised hub having a substantially flat outer surface, and an adjacent cylindrical wall portions having a thinner wall surface that the at least one elongated raised hub; and at least one branch port intersecting the elongated raised hub.

21. The fluid processing system of claim 20, wherein the body block includes first and second opposed elongated raised hubs separated by cylindrical wall portions.

22. The fluid processing system of claim 20, wherein the at least one branch port comprises a threaded port.

23. The fluid processing system of claim 20, wherein the fluid distribution header further comprises a shutoff valve assembled with the at least one branch port.

24. The fluid processing system of claim 20, wherein the fluid distribution header further comprises a mounting bracket configured to engage the substantially flat outer surface of the at least one elongated raised hub to prevent twisting of the body block when the fluid distribution header is mounted to a structure.

25. A fast loop module for a fluid processing system, the fast loop module comprising: an inlet bypass valve having a common port connected to a sample inlet, a first switching port connected to an analyzer supply line, and a second switching port connected to a bypass line; an outlet bypass valve having a common port connected to a sample outlet, a first switching port connected to the analyzer supply line, and a second switching port connected to the bypass line; and a bypass valve actuator operatively connected to each of the inlet and outlet bypass valves, and operable between a first position in which the common ports of the inlet and outlet bypass valves are open to the analyzer supply line, and a second position in which the common ports of the inlet and outlet bypass valves are open to the bypass line.

26. The fast loop module of claim 25, wherein the valve actuator comprises a pivotable handle.

27. The fast loop module of claim 25, further comprising a locking bracket for securing the pivotable handle in one of the first and second positions.

28. The fast loop module of claim 25, wherein the inlet and outlet bypass valves are configured such that the common ports of the inlet and outlet bypass valves are open to at least one of the analyzer supply line and the bypass line at any intermediate position between the first and second positions.

29. The fast loop module of claim 25, further comprising an analyzer return line and a drain valve connected to the analyzer return line for delivering returned fluid to the bypass line in a first switching position and for delivering returned fluid to a drain in a second switching position.

30. The fast loop module of claim 29, wherein the drain valve includes an actuation handle configured to block movement of the bypass valve actuator from the second position to the first position when the drain valve is in the second switching position.

31. The fast loop module of claim 29, wherein the drain valve includes an actuation handle, and the bypass valve actuator blocks movement of the actuation handle from the first switching position to the second switching position when the bypass valve actuator is in the first position.

32. The fast loop module of claim 29, further comprising a purge line connected with the analyzer supply line by a purge valve movable between an open position and a closed position.

33. The fast loop module of claim 32, further comprising an actuation handle operatively connected to each of the drain valve and the purge valve, and operable between a first position in which the purge valve is in the closed position and the drain valve is in the first switching position, and a second position in which the purge valve is in the open position and the drain valve is in the second switching position.

34. A calibration and switching module comprising: at least one sample inlet assembly comprising a double block and bleed stream selection valve operable between an open position for supplying a sample fluid to an outlet flow loop and a closed position for venting an internal sample fluid volume to a common vent; at least one calibration inlet assembly comprising a double block and bleed stream selection valve operable between an open position for supplying a calibration fluid to the outlet flow loop and a closed position for venting an internal calibration fluid volume to the common vent.

35. The calibration and switching module of claim 34, wherein the stream selection valve of the at least one calibration inlet assembly is connected with an automatic air inlet line for automatically supplying a pneumatic signal to actuate the stream selection valve of the at least one calibration inlet assembly from the closed position to the open position.

36. The calibration and switching module of claim 35, further comprising a manual override valve operable for selectively connecting the automatic air inlet line with an air return line and connecting a second air inlet line with the stream selection valve of the at least one calibration inlet assembly to selectively open the stream selection valve of the at least one calibration inlet assembly.

37. The calibration and switching module of claim 34, wherein the at least one calibration inlet assembly comprises first and second calibration inlet assemblies.

38. The calibration and switching module of claim 37, wherein the stream selection valves of the first and second calibration inlet assemblies are connected with corresponding first and second automatic air inlet lines for automatically supplying a pneumatic signal to actuate the stream selection valves of the first and second calibration inlet assemblies from the closed position to the open position.

39. The calibration and switching module of claim 38, further comprising first and manual override valves each operable for selectively connecting the corresponding first and second automatic air inlet lines with an air return line and connecting a third air inlet line with the stream selection valve of the corresponding one of the first and second calibration inlet assembly to selectively open the stream selection valve of the at least one calibration inlet assembly.

40. A field station module comprising: a base member; inlet and outlet ports extending through the base member; a pressure reducing arrangement including a pressure regulator supported by the base member and in fluid communication with the inlet and outlet ports; first and second side rails extending from the base member; an enclosure slideable on the side rails between a lowered position covering the base member and a raised position supported by the side rails and providing access to the pressure reducing arrangement from an entire perimeter of the base member.

41. The field station module of claim 40, further comprising a force-assisted gas spring mechanism to facilitate lifting the enclosure to the raised position.

42. The field station module of claim 41, wherein the enclosure is disengageable from the gas spring mechanism to remove the enclosure from the module.

43. A fluid distribution header comprising: a body block including a cylindrical internal bore opening to a common end port, the body block including at least one elongated raised hub having a substantially flat outer surface, and an adjacent cylindrical wall portions having a thinner wall surface that the at least one elongated raised hub; and at least one branch port intersecting the elongated raised hub.

44. The fluid distribution header of claim 43, wherein the body block includes first and second opposed elongated raised hubs separated by cylindrical wall portions.

45. The fluid distribution header of claim 43, wherein the at least one branch port comprises a threaded port.

46. The fluid distribution header of claim 43, further comprising a shutoff valve assembled with the at least one branch port.

47. The fluid distribution header of claim 43, further comprising a mounting bracket configured to engage the substantially flat outer surface of the at least one elongated raised hub to prevent twisting of the body block when the fluid distribution header is mounted to a structure.