Page 1
Instruction Manual
D103643X012
DFA Desuperheater
October 2017
Fisher
™
DFA Variable Geometry Desuperheater
Contents
Introduction 1.................................
Scope of Manual 1.............................
Description 1.................................
Educational Services 3.........................
Principle of Operation 3.........................
Installation 4..................................
Nozzle Maintenance and Replacement 6...........
DFA Desuperheater Variable Geometry Nozzles 7...
DFA Installation 9.............................
Troubleshooting 9..............................
DFA Parts Ordering 10...........................
Parts List 11...................................
Introduction
Figure 1. Fisher DFA Variable Geometry
Desuperheater
X0838
Scope of Manual
This instruction manual includes installation, maintenance, and operation information for the DFA variable orifice
desuperheater. Refer to separate instruction manuals for information on the actuator and accessories.
Do not install, operate, or maintain a DFA desuperheater without being fully trained and qualified in valve, actuator,
and accessory installation, operation, and maintenance. To avoid personal injury or property damage, it is important
to carefully read, understand, and follow all the contents of this manual, including all safety cautions and warnings. If
you have any questions about these instructions, contact your Emerson sales office
proceeding.
or Local Business Partner before
Description
The Fisher DFA desuperheater flexible architecture (figure 1) incorporates both a water control element and a
variablegeometry mechanically atomized, selfcontained desuperheater for moderate to high flow variation. It is
installed through a flanged connection on the side of an NPS 8 or larger pipeline.
The desuperheater design incorporates an integral thermal liner inside the desuperheater body pipe. This minimizes
the potential for thermal shock when cool water is introduced to the unit which has been heated to the operating
steam temperature.
The nozzle mount for the DFA is engineered to minimize the potential for excitation due to vortex shedding and flow
induced vibration. The DFA desuperheater is installed through a flanged connection on a DN 200 (NPS 8) or larger
pipeline. Maximum nozzle C
is 15.0.
V
www.Fisher.com
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DFA Desuperheater
October 2017
Table 1. Specifications
Available Configurations
(1)
and Valve Sizes
J DFA valve body style: Angle
Common Characteristics: Designed according to ASME
B16.34 Valve-Flanges, Threaded and Welding End
End Connections Styles
(1)
See tables 2 and 3
Maximum Inlet Pressure and Temperature
(1,2)
Flanged, Socketwelding, or Buttwelding: Consistent
with CL150, 300, 600, 900, 1500, and 2500 according
to ASME B16.34, unless limited by maximum pressure
drop or material temperature capabilities
Maximum Pressure Drop
(1)
Valve with Cavitrol™ III Cage: 149 bar (2160 psi) for
two-stage and 207 bar (3000 psi) for three-stage cage.
Consult Fisher Bulletin 80.2:030, Cavitrol III One-, Two-,
and Three-Stage trims, for more information
Anti-cavitation MicroFlat: <51.7 bard (<750 psid)
Inherent Rangeability
Up to 50:1. The ratio of maximum to minimum
controllable C
is dependent upon the available water
v
pressure differential
Instruction Manual
D103643X012
Shutoff Classifications per ANSI/FCI 70-2 and IEC
60534-4
Class V only
Material Temperature Capabilities
Up to 593_C (1100_F) depending on construction
Flow Characteristics
(4)
Standard Cages: J Linear, J equal percentage,
J modified equal percentage
Cavitrol III: Linear
Micro-Flat (with or without liner): Linear
Flow Direction
All: Flow down
Bonnet Style and Mounting
Standard Bonnet
Yoke Temperature Limit: Standard bonnet with cast iron
yoke is limited to 537_C (1000_F)
Packing Arrangements
J Single, J Double, and J Leakoff standard graphite
packing, or optional J ENVIRO-SEAL™ and
J HIGH-SEAL packing systems. See bulletin 59.1:061,
ENVIRO-SEAL and HIGH-SEAL Packing System for
Sliding-Stem Valves
(1)
(5)
(1)
Spray Water Pressure Required
6.9 bar (100 psi) above steam pressure
1. Do not exceed the pressure or temperature limits in this bulletin, nor any applicable code or standard limitations.
2. EN (or other valve body material) ratings and end connections can usually be supplied; consult your Emerson sales office
3. A function of required turndown and equipment selection.
4. Special characterized cages are available. Contact your Emerson sales office or Local Business Partner.
5. Modified equal percentage characteristic is equal percentage for the first 75% of travel, then opens quickly for additional capacity.
(3)
Approximate Weight
See table 12
or Local Business Partner.
The DFA features:
1. Fine atomization over a wide range of operating conditions helping to assure rapid and complete vaporization of
injected water.
2. Available with a wide range of standard and anti-cavitation trim styles.
3. Design minimizes affects of thermal cycling.
4. High turndown capability.
5. Flexible architecture with multiple valve trim combinations and face-to-face dimensions available.
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Instruction Manual
D103643X012
DFA Desuperheater
October 2017
Educational Services
For information on available courses for the Fisher DFA Desuperheater, as well as a variety of other products, contact:
Emerson Automation Solutions
Educational Services - Registration
Phone: 1-641-754-3771 or 1-800-338-8158
E-mail: education@emerson.com
emerson.com/fishervalvetraining
Principle of Operation
The DFA desuperheater reduces steam temperatures through the introduction of cooling water directly into the hot
steam flow stream. By regulating the quantity of water that is injected, accurate downstream steam temperature can
be both controlled and maintained.
The rate of vaporization, and/or cooling, is a function of droplet size, distribution, mass flow, and temperature. Steam
velocity is critical and should be maintained at 6.1 to 9.1 meters per second (20 to 30 feet per second) as the
minimum. Actual minimum steam velocity requirements will vary by application. As steam velocity increases, a longer
distance is required to achieve homogeneous mixing and to complete vaporization.
In DFA desuperheater nozzle styles, the spraywater quantity is controlled by internal control valve which responds to
signals received from the temperature control system. The water enters the main tube of the desuperheater, passes
through the spray nozzle, and discharges into the steam line as a fine, atomized spray (see figure 4).
Each particular nozzle, or set of nozzles, in the sprayhead is tailored to meet a specific set of operating conditions. The
nozzle design optimizes the spraywater droplet size promoting rapid atomization and complete vaporization of water
in the steam flow stream to obtain precise temperature control. The DFA desuperheater uses a variable geometry AF
nozzle. In the AF nozzle design (see figure 4), water enters the swirl chamber via compound angled orifices, thus
creating a rotational flow stream. This flow stream is further accelerated as it is forced up and out through the spray
annulus. The cone‐shaped plug varies the geometry of the spray annulus using a force balance principle between
water pressure and the preload exerted by a helical spring. This variable geometry design sprays a thin hollow cone
over a wide range of flow rates, resulting in excellent temperature control over a wide range of operating conditions.
Figure 2. AF Nozzle Cross Section
PLUG
A7191
BODY
WATER INJECTION HOLES
STEM
SPRING
NUT
PIN
3
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DFA Desuperheater
October 2017
Instruction Manual
D103643X012
Installation
WARNING
Always wear protective gloves, clothing, and eyewear when performing any installation operations to avoid personal
injury.
Personal injury or equipment damage caused by sudden release of pressure may result if the desuperheater is installed
where service conditions could exceed the limits of the pressure class noted on the nameplate. To avoid such injury or
damage, provide a relief valve for over pressure protection as required by government or accepted industry codes and
good engineering practices.
Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
If installing into an existing application, also refer to the WARNING at the beginning of the Maintenance section in this
instruction manual.
Table 2. Desuperheater Connection Size
Design Steam Line Size, NPS
DFA 8 - 60 3 or 4 CL150-2500
1. Other standard flanges and connections are also available.
Size, NPS ASME Pressure Rating Raised-Face Flange(1)
Steam Line Connection
Table 3. Available Valve Connections
Valve Inlet Size, NPS
1,1-1/2, and 2 CL150-2500 RF, RTJ, BW, and SW RF
1. End connection style abbreviations: RF-Raised Face, RTJ-Ring Type Joint, BW-Butt weld, SW-Socket Weld.
2. EN (or other valve body material) ratings and end connections can usually be supplied; consult your Emerson sales office
3. Socket weld available on NPS 1, 1-1/2, and 2 only.
ASME Pressure Rating Raised-Face
Flange(2)
Inlet
(1,2,3)
or Local Business Partner.
Connection
Table 4. Fisher DFA Dimensions
DESUPERHEATER BODY FLANGE
Size, NPS Pressure Rating mm Inches mm Inches
3 and 4
1. The NPS 4 DFA requires a 4.00 inch minimum mounting I.D. Contact your Emerson sales office for NPS 3 DFA minimum mounting I.D.
2. For different centerline to flange face distances Contact your Emerson Automation Solutions sales office.
(1)
CL150-1500 152 6 229 9
CL2500 178 7 241 9.5
INLET CENTERLINE TO OUTLET FLANGE FACE
E
(2)
INLET FLANGE FACE TO OUTLET CENTERLINE
F
Table 5. Fisher DFA Installation Dimensions
DESUPERHEATER
BODY FLANGE SIZE,
NPS
3 and 4
(“D” DIMENSION)
PIPE LINE
Size, NPS mm Inch mm Inch
8 332 13.00 222 8.75
10 358 14.25 222 8.75
12 384 15.25 222 8.75
14 400 15.75 222 8.75
16 425.4 16.75 222 8.75
18 451 17.50 216 8.50
20 477 17.75 222 8.75
22 502 17.75 222 8.75
24 527 17.75 222 8.75
30 600 17.63 219 8.63
(“B” DIMENSION)
INSERTION LENGTH
(“T” DIMENSION)
T-HEIGHT
Outlet
(1,2)
(2)
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Instruction Manual
D103643X012
DFA Desuperheater
October 2017
Table 6. Fisher DFA Minimum Mounting I.D.
MINIMUM BODY FLANGE SIZE
NPS mm Inch
3 DFA- A,B,C
3 DFA- D, E
4 DFA- A through H
NOZZLE MODEL
66.65
73.66
101.6
MINIMUM MOUNTING I.D.
2.624
2.9
4
WARNING
When ordered, the desuperheater configuration and construction materials were selected to meet particular pressure,
temperature, pressure drop, and fluid conditions. Do not apply any other conditions to the desuperheater without first
contacting your Emerson sales office
1. Mount the DFA desuperheater in a “Tee” piece at the desired location in the pipe, in accordance with standard
piping practice. The nozzle should be positioned in the top quadrant of the pipe (see figure 3 for the proper “T”
length dimension).
2. Clean and flush out the cooling water line before connecting to the desuperheater. Use only clean sources of
cooling water. Use of clean water decreases wear and prevents clogging of the nozzle by solid particles.
or Local Business Partner.
WARNING
Personal injury or property damage could result from clogging of the desuperheater. Installation of a strainer and an
isolating valve on the water line between the desuperheater and the water control valve is recommended. Failure to do so
may result in clogging of the desuperheater by solid particles, thus hampering temperature control of the steam.
3. A minimum straight run of pipe is required downstream of the desuperheater, before any elbow or reducer, to
ensure complete vaporization of cooling water. Consult the desuperheater certified drawing for the required
distance of straight pipe.
4. The temperature sensor should be mounted according to the manufacturer's instructions. Typical distance to the
sensor is at least 9.1 meters (30 feet) downstream of the desuperheater. This distance changes with higher velocity
steam flow, elbows, reducers, and the percentage of spraywater required. Consult the desuperheater certified
drawing for this distance.
5. There should be no branching out from or into the steam line to divide the steam flow between the temperature
sensor and the desuperheater.
6. A typical installation is illustrated in figure 6. A temperature sensor element (TE) measures changes in temperature
and transmits a signal to a remote temperature‐indicating controller (TC) or distributed control system (DCS). The
output signal from the controller is sent to the positioner on the spraywater control valve. The positioner output
signal is piped to the actuator. The actuator strokes the stem/plug of the spraywater control valve, as required, to
supply the required cooling water to the desuperheater to maintain temperature setpoint.
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DFA Desuperheater
October 2017
Figure 3. Fisher DFA Dimensions (also see tables 4 and 5)
F
E
Instruction Manual
D103643X012
MOUNTING FLANGE
(SAME SIZE & PRESSURE
CLASS AS BODY FLANGE)
T
NOZZLE APPLICATION
AVAILABLE NOZZLE CONFIGURATIONS
B
FLOW
DIRECTION
FLOW
D
DIRECTION
Nozzle Maintenance and Replacement
If it is necessary to remove the DFA desuperheater from service, take note of the following warning.
WARNING
Avoid personal injury or damage to property from sudden release of pressure or uncontrolled process fluid. Before starting
disassembly:
D Always wear protective gloves, clothing, and eyewear when performing any maintenance operations to avoid personal
injury.
D Isolate the desuperheater from process pressure. Relieve process pressure on both sides of the desuperheater. Drain the
process media from both sides of the desuperheater.
D Use lock‐out procedures to be sure that the above measures stay in effect while you work on the equipment.
D Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
When subjected to normal operating conditions, it is possible that wear, blockage, and/or weld fatigue will occur to
the desuperheater body or nozzle assembly. During regularly scheduled maintenance, visually inspect the
desuperheater welds for cracks and inspect nozzles for wear and blockage. Your local Emerson sales office
or Local
Business Partner can help to determine the extent of weld fatigue and the correct course of action. Poor performing
nozzles or nozzle failure is typically caused by wear, corrosion, erosion, and/or blockage. The following instruction will
help to determine if any of these problems are present and provide a recommended course of action for each.
Note
For optimal performance, nozzles should be inspected every 18-24 months and replaced every 24-36 months.
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Instruction Manual
D103643X012
Figure 4. Fisher AF Nozzle (DFA)
A7191-2D
DFA Desuperheater
October 2017
SPRAY HEAD
SWIRL CHAMBER
WATER INJECTION HOLES
(COMPOUND ANGLED ORIFICES)
SPRING
PLUG STEM
SPRAY PATTERN
SPRING CASING
PIN
SPRAY ANNULUS
TRAVEL MEASUREMENT
DFA Desuperheater Variable Geometry Nozzles
1. Inspect the spray annulus surface, the area between the plug stem and spray head, for excessive wear,
erosion/corrosion, and/or blockage due to particulate. Wear is defined as any nicks, cuts, or gouges on or
immediately around the spray annulus. Erosion/corrosion is defined as any form of rust or erosion of the metal on
the plug stem or spray head. Blockages are defined when small particulate becomes trapped between the plug
stem and spray head or spring casing and spray head. Replacement of the nozzle is recommended if any of the
preceding problems are present.
2. OPTIONAL: Figure 4 shows the spray pattern that will need to be present during operation of the AF nozzles. Testing
can be performed by attaching the existing or an alternate, similar pressure, water line to the unit. If this spray
pattern is not present, replacement is recommended.
3. Grind off the tack welds holding the nozzle in place. Apply a penetrant type thread lubricant and allow to soak prior
to unscrewing the nozzle. Using the provided flats on the side of the spray head, unscrew the nozzle.
4. Grind excess tack weld material off of both the nozzle and desuperheater body.
5. In the absence of external forces, the nozzle must be fully closed. If the nozzle is not fully closed, it will need to be
replaced.
6. Inspect the water injection holes for reduced or non-circular shape due to erosion. Every hole must be the same size
and shape. If any are oversized or non-circular in shape, the nozzle will need to be replaced.
7. Inspect the interior of the water injection holes for buildup of particulate and/or magnetite. Nozzle replacement will
be needed if any buildup is present.
Note
Complete disassembly of the nozzle is strongly discouraged, due to individual spare parts not being available.
8. OPTIONAL: To further check the nozzle for buildup of particulate or magnetite, the nozzle can be disassembled. If
disassembled, take great care not to damage the sharp edges of the spray annulus on the plug stem and the
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DFA Desuperheater
October 2017
Instruction Manual
D103643X012
sprayhead, as this will greatly affect the spray pattern. Do not compress a removed spring by hand or with a tool, as
compression beyond its normal operating range will damage the spring.
To disassemble the nozzle, first remove the pin using a small drill bit as a punch, and unscrew the spring casing from
the plug stem. The nozzle can be reassembled by following a reverse order of disassembly, taking care to line the
hole in the plug stem up with the hole in the spring casing, then pressing the pin back into place through the two
parts.
Table 7. AF Nozzle Specifications
NOZZLE TYPE
AF7 0.356 0.014
AF10 0.711 0.028
AF14 0.737 0.029
AF17 0.864 0.034
AF20 0.914 0.036
AF24 1.067 0.042
AF28 1.122 0.048
AF32 1.422 0.056
AF35 1.651 0.065
AF40 1.600 0.063
AF44 1.753 0.069
mm Inches
PLUG TRAVEL
Figure 5. Spray Nozzle Tack Weld Locations
AF STYLE NOZZLE
GA26453‐B
ORIENTATION OF FLATS NOT CRITICAL
WIRE, TACK
WELD ON BOTH ENDS
9. The travel can be determined by using a feeler gauge to measure the distance between the nozzle body near the
water injection ports to the side of the spring casing as outlined in figure 4. This measurement must match the
factory set plug travel for the corresponding nozzle type as shown in table 7.
10. Inspect nozzle threads for damage and clean if needed; if damage is present, nozzle replacement will be necessary.
11. Rinse both the desuperheater body and nozzle to remove particulate.
12. Screw nozzle into the desuperheater body and tighten just until the spray head is flat and tight against the
desuperheater body.
13. Tackweld a small piece of welding wire onto the nozzle mount next to either of the spray head flats to prevent
rotation during service (refer to figure 5). Maintain low heat to prevent distortion of the nozzle.
14. Reinstall the desuperheater into the line, using a reverse order of assembly; refer to the installation instructions to
complete this step. Make sure the mounting flange gasket (customer supplied) is replaced with a new one.
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Instruction Manual
D103643X012
DFA Desuperheater
October 2017
DFA Installation
Note
Stud(s) and nut(s) should be installed such that the manufacturer's trademark and material grade marking is visible, allowing easy
comparison to the materials selected and documented in the Emerson/Fisher serial card provided with this product.
WARNING
Personal injury or damage to equipment could occur if improper stud and nut materials or parts are used. Do not operate or
assemble this product with stud(s) and nut(s) that are not approved by Emerson/Fisher engineering and/or listed on the
serial card provided with this product. Use of unapproved materials and parts could lead to stresses exceeding the design
or code limits intended for this particular service. Install studs with the material grade and manufacturer's identification
mark visible. Contact your Emerson sales office
and approved parts is suspected.
1. Place the desuperheater portion of the DFA into the line and align with the pin. Nozzles should face downstream.
2. Insert the gasket into the lower portion of the DFA.
3. Slowly lower the valve body onto the desuperheater portion and ensure that the alignment pin from the lower
portion slides into the corresponding hole in the valve body.
4. Completely lower the valve body onto the lower portion and bolt into place using the recommended line gasket
bolting torques.
or Local Business Partner immediately if a discrepancy between actual parts
Troubleshooting
Table 8 is intended as a basic first line troubleshooting guide. Contact your local Emerson sales office or Local Business
Partner for assistance if you are unable to resolve your field operation problem.
Table 8. Troubleshooting Guide
Problem Corrective Action
Temperature setpoint is not reached Check water source availability and pressure
Temperature setpoint is not reached Check nozzle(s) for plugging
Temperature setpoint is not reached Make sure that steam saturation pressure is not above setpoint
Temperature setpoint is not reached Check to ensure full actuator stroke is reached on the spraywater control valve
Temperature setpoint is not reached Check for proper orientation of nozzle in steam flow
Temperature is below setpoint Check temperature control loop ‐ reset
Temperature is below setpoint Check nozzle for fouling/poor spray pattern ‐ clean/replace
Temperature is below setpoint Check temperature sensor location ‐ relocate per guidelines
Temperature is below setpoint Check for proper orientation of nozzle in steam flow
Water in steam line Check that steam traps are functioning properly
Water in steam line when steam line isolated Check for proper spraywater control valve actuator installation
Water in steam line when steam line isolated Replace spraywater control valve seat and plug assembly
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DFA Desuperheater
October 2017
Figure 6. Typical DFA Installation
SPRAYWATER
DFA DESUPERHEATER
WITH ACTUATOR
Instruction Manual
D103643X012
B
C
A
D
STEAMFLOW
STEAM FLOW DIRECTION
(TOP VIEW)
DFA Parts Ordering
Each desuperheater assembly is assigned a serial number which can be found on the mounting flange of the
desuperheater. Refer to the serial number when contacting your Emerson sales office
technical assistance. When ordering numbers for each part required, the key numbers on figure 7 can be used to help
in part identification.
WARNING
Use only genuine Fisher replacement parts. Components that are not supplied by Emerson Automation Solutions should
not, under any circumstances, be used in any Fisher valve, because they may void your warranty, might adversely affect the
performance of the valve, and could cause personal injury and property damage.
or Local Business Partner for
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Instruction Manual
D103643X012
Parts List
Key Description
1 Nozzle Mount
2* Spray Nozzle
3 Body Flange
4* Desuperheater Gasket
5 Alignment Pin
6* Seat Gasket
7* Seat
8* Plug Stem Assembly
9* Cage
10 Valve Body
11* Bonnet Gasket
12 Bonnet Stud
13 Bonnet Stud Nut
14 Bonnet
15* Packing Box Ring
16* Lantern Ring
17* Packing Rings
18 Packing Follower
19 Packing Flange
20 Packing Flange Nut
21 Packing Flange Stud
Table 12. Fisher DFA Weights
OUTLET CONNECTION,
NPS
3
4
1. Desuperheater section weighs about 11.4 kg (25 lbs).
INLET CONNECTION,
(1)
NPS
1
1-1/2
2
1
1-1/2
2
DFA Desuperheater
Table 9. Desuperheater Gasket
VALVE SIZE, NPS CLASS PART NUMBER
3 and 4 CL150 - CL1500 12B4275X042
Table 10. Bonnet Parts
VALVE SIZE, NPS CLASS
1, 1-1/2, and 2 CL150 - CL600 EA
1, 1-1/2, and 2 CL900 - CL2500 HPA
INSTRUCTION
Table 11. Trim Parts
VALVE SIZE, NPS CLASS
1, 1-1/2, and 2 CL150 - CL600 EA
1, 1-1/2, and 2 CL900 - CL2500 HPA
CLASS
600 128 283
1500 183 403
2500 253 558
600 137 301
1500 193 426
2500 273 602
600 138 304
1500 206 454
2500 287 633
600 179 394
1500 224 494
2500 312 688
600 191 420
1500 237 522
2500 337 743
600 193 425
1500 253 558
2500 354 781
APPROXIMATE WEIGHT
kg lbs
INSTRUCTION
October 2017
BULLETIN/
MANUAL
BULLETIN/
MANUAL
*Recommended spare parts
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DFA Desuperheater
October 2017
Figure 7. DFA Assembly
Instruction Manual
D103643X012
NOTE: IMAGE SHOWN WITH ANTICAV MICROFLAT. OTHER OPTIONS ARE AVAILABLE.
Neither Emerson, Emerson Automation Solutions, nor any of their affiliated entities assumes responsibility for the selection, use or maintenance
of any product. Responsibility for proper selection, use, and maintenance of any product remains solely with the purchaser and end user.
Fisher, Cavitrol, and ENVIRO-SEAL are marks owned by one of the companies in the Emerson Automation Solutions business unit of Emerson Electric Co.
Emerson Automation Solutions, Emerson, and the Emerson logo are trademarks and service marks of Emerson Electric Co. All other marks are the property
of their respective owners.
The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not
to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are
governed by our terms and conditions, which are available upon request. We reserve the right to modify or improve the designs or specifications of such
products at any time without notice.
Emerson Automation Solutions
Marshalltown, Iowa 50158 USA
Sorocaba, 18087 Brazil
Cernay 68700 France
Dubai, United Arab Emirates
Singapore 128461 Singapore
www.Fisher.com
12
E 2013, 2017 Fisher Controls International LLC. All rights reserved.
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