Emerson Fisher DFA Instruction Manual

Instruction Manual

D103643X012

DFA Desuperheater

August 2013

Fisherr 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...................................

Figure 1. Fisher DFA Variable Geometry
Desuperheater

Introduction

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 Process Management sales office before
proceeding.

Description

The Fisher DFA desuperheater flexible architecture (figure 1) incorporates both a water control element and a
variablegeometry mechanically atomized, selfcontained 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.

ThenozzlemountfortheDFAisengineeredtominimizethepotential 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 unit C

www.Fisher.com

is 15.0.

V

DFA Desuperheater

August 2013

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: Linear

Flow Direction

Standard Cage (Micro-Flat):Flowdown
Cavitrol III Cage: 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) or larger is acceptable

1. Do not exceed thepressure or temperature limits in this bulletin, nor any applicable code or standard limitations.

2. EN (or other valvebody material) ratings and end connections can usually be supplied; consult your Emerson Process Management sales office.

3. A function of requiredturndown and equipment selection.

4. Special characterized cages are available. Contact your Emerson Process Management sales office.

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

The DF A 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. Designminimizesaffectsofthermalcycling.

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

August 2013

Educational Services

For information on available courses for the Fisher DFA Desuperheater, as well as a variety of other products, contact:

Emerson Process Management
Educational Services, Registration
P.O. Box 190; 301 S. 1

st

Ave.
Marshalltown, IA 50158-2823
Phone: [phone] or
Phone: [phone]
FAX: [phone]
e-mail: [e-mail]

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 operatingconditions. 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 desuperheaterusesavariablegeometryAF
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

STEM

BODY

SPRING

PLUG

A7191

NUT

PIN

WATER INJECTION HOLES

3

DFA Desuperheater

August 2013

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 3or4 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 TypeJoint, BW-Butt weld, SW-Socket Weld.

2. EN (or other valve body material) ratings andend connections can usually be supplied; consult your EmersonProcess Management 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)

Connection

Table 4. Fisher DFA Dimensions

DESUPERHEATER BODY FLANGE

Size, NPS Pressure Rating mm Inches mm Inches

3and4

1. The NPS 4 DFA requires a 4.00 inch minimum mounting I.D. Contact your Emerson Process Management sales office for NPS 3 DFA minimum mounting I.D.

2. For different centerline to flange face distances Contact your Emerson Process Management sales office.

(1)

CL150-1500 152 6 229 9

CL2500 178 7 241 9.5

INLETCENTERLINETOOUTLETFLANGEFACE

E

(2)

INLETFLANGEFACETOOUTLETCENTERLINE

F

Table 5. Fisher DFA Installation Dimensions

DESUPERHEATER

BODY FLANGE SIZE,

NPS

3and4

(“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

August 2013

Table 6. Fisher DFA Minimum Mounting I.D.

MINIMUM BODY FLANGE NOZZLE MODEL MINIMUM MOUNTING I.D.

3 DFA- A,B,C 2.624

3 DFA- D, E 2.9

4 DFA- A through H 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 Process Management sales office.

1. Mount the DFA desuperheater in a “Tee” piece at the desiredlocationinthepipe,inaccordancewithstandard
pipingpractice.Thenozzleshouldbepositionedinthetopquadrantofthepipe(seefigure3fortheproper“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.

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 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
steamflowandthepercentageofspraywaterrequired.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.

5

DFA Desuperheater

August 2013

Figure 3. Fisher DFA Dimensions (also see tables 4 and 5)

F

MOUNTINGFLANGE
(SAMESIZE&PRESSURE
CLASSASBODYFLANGE)

E

T

Instruction Manual

D103643X012

NOZZLE APPLICATION

AVAILABLE NOZZLE CONFIGURATIONS

B

FLOW

DIRECTION

FLOW

D

DIRECTION

Nozzle Maintenance and Replacement

IfitisnecessarytoremovetheDFAdesuperheaterfromservice,takenoteofthefollowingwarning.

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 Process Management
Instrument and Valve Services office 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 recomm ended course
of action for each.

Note

For optimal performance, nozzles should be inspected every 18-24 months and replaced every 24-36 months.

6

Instruction Manual

D103643X012

Figure 4. Fisher AF Nozzle (DFA)

SPRAY PATTERN

SPRAY ANNULUS

A7191-2D

DFA Desuperheater

August 2013

SPRAY HEAD

SWIRL CHAMBER

WATER INJECTION HOLES
(COMPOUNDANGLEDORIFICES)

SPRING

PLUG STEM

SPRING CASING

PIN

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 oversized 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: The internal spring may relax over time and not provide the tensile force required to shut off and control
flow.Ifthenozzlespringissuspectedofbeingtoorelaxed,thenthenozzleshouldbereplaced.

7

DFA Desuperheater

August 2013

Table7.AFNozzleSpecifications

NOZZLE TYPE PLUG TRAVEL, INCHES

AF7 0.014

AF10 0.028

AF14 0.029

AF17 0.034

AF20 0.036

AF24 0.042

AF28 0.048

AF32 0.056

AF35 0.065

AF40 0.063

AF44 0.069

Figure 5. Spray Nozzle Tack Weld Locations

AF STYLE NOZZLE

Instruction Manual

D103643X012

GA26453-B

ORIENTATION OF FLATS NOT CRITICAL

WIRE, TACK
WELD ON BOTH ENDS

To further check the spring, the spring can be removed by first removing the pin, using a small drill bit as a punch and
unscrewing 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.

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 andnozzletoremoveparticulate.

12. Screw nozzle into the desuperheater body and tighten just until the spray head is flat and tight against the
desuperheater body.

13. Tackweld 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.

8

Instruction Manual

D103643X012

DFA Desuperheater

August 2013

DFA Installation

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.

Troubleshooting

Table 8 is intended as a basic first line troubleshooting guide. Contact your local Emerson Process Management sales
office representative 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 Makesure 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 temperaturecontrol 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 valveactuator installation

Water in steam line when steam line isolated Replace spraywater control valve seat and plug assembly

9

DFA Desuperheater

August 2013

Figure 6. Typical DFA Installation

SPRAYWATER

Instruction Manual

D103643X012

DFA DESUPERHEATER
WITH 657 ACTUATOR

STEAMFLOW

DFA Parts Ordering

Each desuperheater assembly is assigned a serial numberwhichcanbefoundonthemountingflangeofthe
desuperheater. Refer to the serial number when contacting your Emerson Process Management sales office for
technical assistance. When ordering numbers for each part required, the key numbers o n figure 7 can be used to help
in part identification.

WARNING

Use only genuine Fisher replacement parts. Components that are not supplied by Emerson Process Management 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.

10

Instruction Manual

D103643X012

Parts List

Key Description

1 Nozzle Mount
2* Spray Nozzle
3BodyFlange
4* Desuperheater Gasket
5 Alignment Pin
6* Seat Gasket
7* Seat
8* Plug StemAssembly

9* Cage
10 Valve Body
11* BonnetGasket
12 Bonnet Stud
13 Bonnet Stud Nut
14 Bonnet
15* PackingBox Ring
16* LanternRing
17* PackingRings
18 Packing Follower
19 Packing Flange
20 Packing Flange Nut
21 Packing Flange Stud

Table 12. Fisher DFA Weig hts

OUTLET CONNECTION INLET CONNECTION CLASS

3

4

1. Desuperheater section weighs about11.4 kg (25 lbs).

(1)

1

1-1/2

2

1

1-1/2

2

DFA Desuperheater

Table 9. Desuperheater Gasket

VALVE SIZE, NPS CLASS PART NUMBER

3and4 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

BULLETIN/

INSTRUCTION

MANUAL

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

APPROXIMATE WEIGHT

kg lbs

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

BULLETIN/

INSTRUCTION

MANUAL

August 2013

*Recommended spare parts

11

DFA Desuperheater

August 2013

Figure 7. DFA Assembly

Instruction Manual

D103643X012

NOTE: IMAGE SHOWN WITH ANTICAV MICROFLAT. OTHER OPTIONS ARE AVAILABLE.

Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use or maintenance
of any product. Responsibilityfor proper selection, use, and maintenance of any product remains solely with the purchaser and end user.

Fisher is a mark owned by one of the companiesin the Emerson Process Management business unit of EmersonElectric Co. Emerson Process Management,
Emerson, and the Emerson logo are trademarks and servicemarks 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 arenot
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 rightto modify or improve the designs orspecifications of such
products at any time without notice.

Emerson Process Management
Marshalltown, Iowa 50158 USA
Sorocaba, 18087 Brazil
Chatham, Kent ME4 4QZ UK
Dubai, United Arab Emirates
Singapore 128461 Singapore

www.Fisher.com

12

E 2013 Fisher Controls International LLC. All rights reserved.