1. The Swagelok® SSV Series Stream Selector System for Process Analyzer Applications
Swagelok introduced the next generation of stream selection technology in October This was in direct response to the market need for timely and pure samples with reduced risk of leakage to atmosphere and the market’s request for a stream select valve compliant to the ANSI/ISA specification.

2. Stream Selector Overview
Directs individual streams to an analyzer
Eliminates the need for multiple analyzers
Ensures a pure stream sent to analyzer
Return
Process Fluid A
Process Fluid B
Stream Selector
In many systems, one analyzer may be required to evaluate several different streams coming from multiple sample points in the process. In systems like this, the sample streams will pass through a selection system that allows one sample at a time to be sent to the analyzer. This practice is used in order to reduce the need to have an analyzer dedicated to every sample stream, therefore saving money. In addition, stream selection is used for calibration purposes where one or more fluid is the sample and the other two are for calibration gases. This example shows three streams. A typical system will be anywhere from 2 to 12 streams.
Analyzer
Process Fluid C

3. Types of Stream Selection Technology
Double Block and Bleed - Conventional
Double Block and Bleed - Cascading
Double Block and Bleed - Outlet Flow Loop
There are three types of stream selection technology:
Conventional double block and bleed, cascading, and outlet flow loop.
Double block and bleed (DBB) designs are popular in industry because of concern about cross-contamination in the event of seal failure. All three types of systems use double block and bleed technology. In a DBB system, there are two valves separating the analyzer from the sample stream with a vent in between. Redundant sealing is present in case of seal failure. All of these designs are intended to supply a pure stream to the analyzer and prevent cross-stream contamination.
Each of these will be discussed in detail.

4. Double Block and Bleed – Conventional
Stream 1
Stream 2
Stream 3
Block
Valves
To Vent
To Analyzer
A conventional double block and bleed three-stream system can be built with both 2-way or 3-way valves. Typically, these are ball valves.
Each sample stream contains two valves in series which block sample flow to the analyzer when in the closed position.
When these block valves are closed, a bleed valve is opened which permits the volume between the block valves to be vented to atmosphere or captured within a vent system.
As the block valves are opened, the vent will close and that sample stream is sent to the analyzer.

5. Double Block and Bleed – Conventional
Limitations
Un-purged dead-leg
Large footprint
Internal volume
Assembly and maintenance
Dead Leg
While this type of design does prevent cross-contamination, it is poor at assuring a pure sample is delivered to the analyzer. This is due to the “dead leg” as noted here. In a dead-leg, previous un-purged sample could contaminate the current sample being analyzed. This may cause an erroneous analyzer reading.
These types of systems are typically fabricated of valves, fittings, and tubing contributing to a large footprint, significant internal volume, and requirement for skilled workers to assemble and maintain the system.

6. Double Block and Bleed – Cascading
Stream 1
Stream 3
Stream 2
To Analyzer
To Vent
Over the past 15 to 20 years, modular stream select assemblies have been adopted by the market which reduce the footprint, internal volume, and maintenance required.
The second type of stream selection is a cascading type design. Cascading systems can be constructed using either conventional or modular designs. Cascading designs are very good at assuring a pure sample is being delivered to the analyzer.

7. Double Block and Bleed – Cascading
Stream 1
Stream 3
Stream 2
To Analyzer
To Vent
As sample media flows through the system, stream 1 and 2 are blocked by the first block valve. In stream 3, both block valves are open and the system media is flowing through this path. To continue to the analyzer, the system media flows through the second block valve of stream 1 and stream 2 therefore purging any previous sample.

8. Double Block and Bleed – Cascading
Stream 1
Stream 3
Stream 2
To Analyzer
To Vent
As stream 3 is closed, flow is stopped and sample media contained between the two block valves is vented.

9. Double Block and Bleed – Cascading
Stream 1
Stream 3
Stream 2
To Analyzer
To Vent
Stream 1 is now open, while stream 2 and 3 are blocked. Stream 1 continues through the second block valve and onto the analyzer. Adequate time must be allotted for the previous sample to purge prior to analyzing.

10. Double Block and Bleed – Cascading
Limitations
Reduced flow with additional streams
Inconsistent purge time from stream to stream
As you can see with stream 3, in order for the system media to transfer to the analyzer, it must pass through three block valves. Each block valve creates a pressure drop in the system which restricts flow. This will increase time to obtain an analyzer reading.
Testing has shown that with each stream added, 20 % reduction in flow, per stream, occurs. Eventually, flow may completely stop.
Due to the various flow rates of different streams, purge time will vary greatly. Typically customers will set the delay time to the longest purge stream. This results in wasted samples in shorter purge streams and increased time between analysis of each stream.

11. Double Block and Bleed – Outlet Flow Loop
to analyzer
to vent
Stream 1
Stream 2
Stream 3
The third type of stream selection is the outlet flow loop design. In this design, a flow loop is created separate from the block valves.

12. Double Block and Bleed – Outlet Flow Loop
Stream 1
to analyzer
Stream 2
Here, stream 1 is open and stream 2 and 3 are blocked. Stream 1 continues through the outlet flow loop and onto the analyzer. The vent valve in stream 1 is closed and in stream 2 and 3, the vent is open.
Stream 3
to vent

13. Double Block and Bleed – Outlet Flow Loop
Stream 1
to analyzer
Stream 2
The valves in stream 1 now close and the media trapped between the two block valves is vented through a common vent.
Stream 3
to vent

14. Double Block and Bleed – Outlet Flow Loop
Stream 1
to analyzer
Stream 2
As stream 3 is opened, the system media will flow through the block valves and purge the remaining stream 1 media through the outlet flow loop. Adequate time must be allotted for the previous sample to purge prior to analyzing. This applies to both cascading and outlet flow loop designs.
Stream 3
to vent

15. Double Block and Bleed – Outlet Flow Loop
Stream 1
to analyzer
Stream 2
Here you can see the system media from stream 3 flowing through the outlet flow loop and onto the analyzer.
Stream 3
to vent

16. Double Block and Bleed – Outlet Flow Loop
Advantages
Overcomes traditional DBB and cascading design limitations
Consistent flow
Number of streams
Stream location
Pure sample
The outlet flow loop design overcomes the limitations of traditional DBB and cascading designs by utilizing an outlet flow loop. This allows for consistent flow and purging while still assuring a pure sample. Regardless of the number of streams or where this stream is located, the flow will be consistent. This allows the time delay to be set for a minimum amount of time, thus reduces wasted sample and increases the timeliness of the analyzer reading.

17. The Swagelok SSV Series
Outlet flow loop design
Double block and bleed function in one compact valve module
System pressures to 250 psig (17.2 bar)
Temperatures to 300F (148C)
40 psig (2.8 bar) actuator pressure
316 SS construction, fluorocarbon FKM or Kalrez seals
1/8 in. FNPT and ANSI/ISA configurations

18. SSV Primary Components
DBB module
Base block
The primary components that make the SSV series work are the valve module which contains the double block and bleed function, and the base block which houses the fluid connections, porting, and outlet flow loop.

19. System Overview Air Actuator Inlet Ports Inlet Ports Outlet Port
This is a three stream system. The 1/8 in. FNPT inlet ports are shown here for each valve module.
CLICK
On the opposite side, the 1/8 in. FNPT outlet port and the individual air actuator ports are contained. Also in this view, the common vent port can be seen on the side of the end block.
To demonstrate how the internal porting works, we will look at three cross-sections of the stream selector system.
Vent Port

20. Inlet Flow Section
This shows the inlet section of the SSV. Flow enters each stream through a 1/8 in. FNPT in the base block and is directed up into the DBB valve module.

21. Vent Flow Section Vent Port Insert Screw Insert
Next, we will look at the vent section. All DBB valve modules are connected to a common vent line in the base blocks. This common vent is ported out through the end blocks to atmosphere or a vent collection system.
Insert Screw
Insert

22. Outlet Flow Section
Finally, we will look at the outlet flow loop. Flow enters the base block through the open DBB valve module. The system media then flows through the outlet flow loop and into the 1/8 in. FNPT common outlet port in the single base block.

23. DBB Valve Body Multiple valve functions in a single compact unit
Let’s turn our attention to the DBB valve module. Here, media flow, shown in green, is contained by the first block seal.
CLICK
The valve is actuated which opens the 2 block seals and closes the vent. This it depicted in green. Flow is now open from the inlet to the outlet flow loop and onto the analyzer.
The inlet and outlet ports are now closed and the vent is open. The venting fluid is shown in blue. It is important to note that this module contains 2 block seals preventing the inlet stream from flowing to the outlet flow loop.

24. SSV Benefits Easy to assemble and maintain Visual indication
DBB Valve module
Base blocks
Visual indication
Unique vented air gap
Integrated outlet flow loop
Compact size
40 psig (2.8 bar) actuation pressure
ANSI/ISA Compatible
Let’s review the benefits of the Swagelok SSV system. We will review each of these individually in the coming slides.
Easy to assemble and maintain
Visual indication
Unique vented air gap
Integrated outlet flow loop
Interlocking screws (patent pending)
Compact size
40 psig actuation pressure
ANSI/ISA Compatible

25. SSV Benefits Easy to assemble and maintain – DBB Valve Module
All process connections in the base block
DBB Valve Module easily removed with two screws
O-ring kits available
Click graphic to animate.
As you can see, the DBB valve module is connected to the base block with 2 screws. These can be quickly removed for servicing without having to disconnect any fluid connections.

26. SSV Benefits Easy to assemble and maintain – Base Blocks
Interlocking screws (patent pending)
Click graphic to animate
The Swagelok SSV series contains a unique patent-pending connection method. Connection screws are contained within the base-block and attach to the adjacent interlocking threaded insert. This containment assures that the screws remain within the base block eliminating the opportunity to lose or mix screws. Each base block is independently attached to the adjoining base block. This eliminates the opportunity to accidentally loosen downstream blocks when servicing or adding to the system.

27. SSV Benefits Visual Indicators
Large green indicator ring rises above cylinder
Provides obvious visual and tactile indication
Colored button on top for stream identification
Click picture to animate.
Users of stream select systems require knowledge of what system is open at any given time. The Swagelok SSV system addresses this need with an obvious visual indicator. As you can see from this lab testing footage, the top of the piston has a bright green indicator ring. This provides immediate indication of actuation.
A number of different colored caps are available for stream identification.

28. SSV Benefits Unique Vented Air Gap
Prevents system media from entering air actuator supply
Prevents air actuator gas from mixing with system media
Optional threaded version available
The SSV is the only stream selector to utilize a vented air gap. The vented air gap is a feature that prevents system media and air actuator supply gas from combining.
If either of the lower or upper stem seals become compromised, there is a common vent in between both to safely carry the media out of the DBB valve module. Therefore, the SSV valve module prevents:
system media from mixing with the air actuator supply gas and contaminating the facility’s air system
air actuator supply gas from mixing with the sample resulting in inaccurate analyzer readings
and a combustive mixture of air actuator supply gas and media resulting in a possible explosive environment.
This 1/8 in. FNPT vent port is also available to direct the venting fluid to a specific location.

29. SSV Benefits Integrated Outlet Flow Loop
Provides consistent flow regardless of how many streams are added
Outlet of stream selector assembly
Cv=0.20
As discussed earlier, the outlet flow loop provides consistent flow through regardless of the number streams. This has been verified through both computational fluid dynamics (CFD) and lab testing. Regardless of the number of streams, or the location of the stream selected, the Cv of the system is still 0.20

30. SSV Benefits Compact Size
Cascading Design » Footprint: 18.9 in2 (121.9 cm2)
6.51 in.
2.91 in.
In general modular designs are more compact than the conventional double block and bleed configurations. Here is a typical three stream cascading modular system that occupies almost 19 square inches (122 square centimeters) of space.

31. 46 % smaller SSV Benefits Compact Size
Cascading Design » Footprint: 18.9 in2 (121.9 cm2)
SSV Footprint: 10.1 in2 (65.2 cm2)
46 % smaller
6.51 in.
2.91”
1.50 in.
6.76 in.
In contrast, the Swagelok SSV which is a outlet flow loop design, takes up about 10 square inches (65 square centimeters) of space.
CLICK
This is a reduction in space of almost 50 %!!

32. SSV Benefits 40 psig (2.8 bar) actuation pressure
The SSV can be actuated by normal instrument or shop air. As you can see from this chart, for applications 30F (-1C) and above, 40 psi (2.8 bar) is suitable to actuate this product.

33. SSV Benefits ANSI/ISA 76.00.02 Compatible
Compatible with Swagelok MPC series
The Swagelok SSV stream selector system is compatible with ANSI/ISA This means the system, with a special bottom porting, can be mounted to an MPC substrate.

34. MPC Configurator Configurator screen with SSV layout
To aid in the design of systems with stream selection, the Swagelok SSV series is incorporated into the MPC configurator.

35. SSV Options Atmospheric Reference Vent Analyzer
In addition to all of the benefits we have discussed, special configurations can be ordered for your application. The integrated atmospheric reference vent (ARV) is positioned prior to the analyzer and attached to the outlet of the stream selector system. It is designed to equalize the sample loop pressure to atmospheric pressure just prior to the sample injection. This ensures a constant sample pressure in repetitive analyses.
Analyzer

36. SSV Options 2 to 12 streams, standard
Standard, the SSV system is available in 2 to 12 streams.
CLICK
As we discussed earlier, flow is not reduced when additional streams are added. Any number of streams can be added to this product.

37. Product Test Reports
PTR-1152 Cycle Test of Swagelok Stream Selector System
Tested to observe mean time to failure (MTTF)
Test pressure: 250 psig (17.2 bar)
Temperature: room
To confirm the robustness of this design, a series of tests were run and published in Swagelok Product Test Reports. In this particular test, the product was cycled to failure at a test pressure of 250 psig (17.2 bar). The mean time to failure or where half of the product failed was 6.76 million cycles. If your application cycles once every ten minutes, based upon this data the life expectancy of this valve is over 125 years!!

38. Product Test Reports
PTR-1211 Venting Volume of Swagelok Stream Selector System with Water Flow
Tested to determine volume of system fluid vented during an individual cycle.
Test pressure: inlet 250 psig (17.2 bar); outlet 200 psig (13.7 bar)
Temperature: room
During the time of actuation, for a fraction of a second, both block seals and the vent seal are all open. In this report, it shows at the lowest actuation pressure, less than cubic inches (1.25 cubic centimeters) of fluid is vented. As you can see, as actuation pressure increases, this volume decreases.

39. Product Test Reports
PTR-1317 Long-Term, High Temperature Testing of Swagelok Stream Selector System
Tested to verify leak performance after cycling for 30 days
Test pressure: 100 psig (6.8 bar)
Temperature: 200F (93C )
The SSV system was tested to verify leak performance after cycling for 30 days. With a test pressure of 100 psig (6.8 bar) and a temperature of 200F (93C) the product did not exhibit leakage after 30 days or cycles over 1 standard cubic centimeter per minute.

40. SSV Summary Overcome limitations Benefits
Conventional systems – dead-legs
Cascading systems – reduced flow
Benefits
Easy to assemble and maintain
Visual indication
Unique vented air gap
Compact size
40 psig (2.8 bar) actuation pressure
ANSI/ISA Compatible
In summary, the Swagelok SSV series has overcome the limitations of previous stream selection technologies. The outlet flow loop eliminates the dead-legs associated with conventional systems and provides consistent flow which ensures a timely sample to be delivered to the analyzer.
As we have discussed, the SSV also includes additional benefits over other modular stream select designs. Among these are improved ease of assembly and maintenance. Clear and tactile indication. A vented air gap to ensure system media does not mix with air actuator gas. A size that is almost ½ the size of other modular cascading type systems. A 40 psig (2.8 bar) actuation pressure which is less than standard instrument air. And it is offered in both conventional, as well as MPC footprint.