Gas Stop/Ratio Valve
Product Manual 26620
(Revision D, 10/2013)
Original Instructions
Gas Stop/Ratio Valve
This manual is based on manual 26093 revision R.
Installation and Operation Manual
Read this entire manual and all other publications pertaining to the work to be
performed before installing, operating, or servicing this equipment.
Practice all plant and safety instructions and precautions.
General
Precautions Failure to follow instructions can cause personal injury and/or property damage.
Revisions
This publication may have been revised or updated since this copy was produced.
To verify that you have the latest revision, check manual 26311 , Revision Status &
Distribution Restrictions of Woodward Technical Publications, on the publications
page of the Woodward website:
www.woodward.com/publications
The latest version of most publications is available on the publications page. If
your publication is not there, please contact your customer service representative
to get the latest copy.
Proper Use
Any unauthorized modifications to or use of this equipment outside its specified
mechanical, electrical, or other operating limits may cause personal injury and/or
property damage, including damage to the equipment. Any such unauthorized
modifications: (i) constitute "misuse" and/or "negligence" within the meaning of
the product warranty thereby excluding warranty coverage for any resulting
damage, and (ii) invalidate product certifications or listings.
If the cover of this publication states "Translation of the Original Instructions"
please note:
The original source of this publication may have been updated since this
Translated translation was made. Be sure to check manual 26311 , Revision Status &
Publications Distribution Restrictions of Woodward Technical Publications, to verify whether
this translation is up to date. Out-of-date translations are marked with . Always
compare with the original for technical specifications and for proper and safe
installation and operation procedures.
Revisions—Changes in this publication since the last revision are indicated by a black line
alongside the text.
Woodward reserves the right to update any portion of this publication at any time. Information provided by Woodward is
believed to be correct and reliable. However, no responsibility is assumed by Woodward unless otherwise expressly
undertaken.
Manual 26620
Copyright © Woodward 2011–2013
All Rights Reserved
Manual 26620
Gas Stop/Ratio Valve
Contents
WARNINGS AND NOTICES ............................................................................III ELECTROSTATIC DISCHARGE AWARENESS ................................................. IV REGULATORY COMPLIANCE ........................................................................ V CHAPTER 1. GENERAL INFORMATION ........................................................... 1 Gas Stop/Ratio Valve Functional Characteristics ..................................................2 CHAPTER 2. STOP/RATIO VALVE OPERATION ............................................ 23 CHAPTER 3. STANDARD COMPONENT DETAILS .......................................... 24 Triple Coil Electrohydraulic Servo Valve Assembly .............................................24 Trip Relay Valve Assembly...................................................................................24 Hydraulic Filter Assembly .....................................................................................25 LVDT Position Feedback Sensors .......................................................................25 CHAPTER 4. INSTALLATION........................................................................ 26 General .................................................................................................................26 Unpacking .............................................................................................................27 Piping Installation .................................................................................................27 Hydraulic Connections..........................................................................................28 Electrical Connections ..........................................................................................28 Fuel Vent Port .......................................................................................................29 Electronic Settings ................................................................................................29 CHAPTER 5. MAINTENANCE AND HARDWARE REPLACEMENT ..................... 31 Maintenance .........................................................................................................31 Hardware Replacement ........................................................................................31 Troubleshooting Charts ........................................................................................36 CHAPTER 6. SERVICE OPTIONS ................................................................. 38 Product Service Options .......................................................................................38 Woodward Factory Servicing Options ..................................................................39 Returning Equipment for Repair ...........................................................................39 Replacement Parts ...............................................................................................40 Engineering Services............................................................................................40 How to Contact Woodward ...................................................................................41 Technical Assistance ............................................................................................41 REVISION HISTORY .................................................................................... 42 DECLARATIONS ......................................................................................... 43 Woodward
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Illustrations and Tables
Figure 1-1. Gas Stop/Ratio Valve (typical; 3-inch shown) ......................................3 Figure 1-2. Single Acting Hydraulic Schematic ......................................................4 Figure 1-3a. Electrical Schematic and Wiring Diagram (Dual LVDT).....................5 Figure 1-3b. Electrical Schematic and Wiring Diagram (Triple LVDT, 6” and 8”
valves only) ........................................................................................5 Figure 1-4a. LVDT Barrier Wiring Diagram (TIIS requirement, Japan) ..................6 Figure 1-4b. Servo Valve Barrier Wiring Diagram (TIIS requirement, Japan) ........7 Figure 1-5a. Gas Stop/Ratio Valve Outline Drawing (3-inch) .................................9 Figure 1-5b. Gas Stop/Ratio Valve Outline Drawing (3-inch) ...............................10 Figure 1-6a. Gas Stop/Ratio Valve Outline Drawing (4-inch) ...............................11 Figure 1-6b. Gas Stop/Ratio Valve Outline Drawing (4-inch) ...............................12 Figure 1-7a. Gas Stop/Ratio Valve Outline Drawing (6-inch, except SS-260) .....13 Figure 1-7b. Gas Stop/Ratio Valve Outline Drawing (6-inch, except SS-260) .....14 Figure 1-8a. Gas Stop/Ratio Valve Outline Drawing (6-inch, SS-260).................15 Figure 1-8b. Gas Stop/Ratio Valve Outline Drawing (6-inch, SS-260).................16 Figure 1-9a. Gas Stop/Ratio Valve Outline Drawing (6-inch, with 3 LVDTs,
SS-260) ............................................................................................17 Figure 1-9b. Gas Stop/Ratio Valve Outline Drawing (6-inch, with 3 LVDTs,
SS-260) ............................................................................................18 Figure 1-10a. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 2 LVDTs) .....19 Figure 1-10b. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 2 LVDTs) .....20 Figure 1-11a. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 3 LVDTs) .....21 Figure 1-11b. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 3 LVDTs) .....22 Figure 4-1. Stop/Ratio Valve Block Diagram ........................................................29 Figure 4-2. Structures for PID Control ..................................................................30 Figure 5-1. Stroke Measurement Attachment Bar ................................................35 Table 3-1. Recommended Control Gain Values for Different Control Types .......30 ii
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Gas Stop/Ratio Valve
Warnings and Notices
Important Definitions





This is the safety alert symbol. It is used to alert you to potential
personal injury hazards. Obey all safety messages that follow this
symbol to avoid possible injury or death.
DANGER—Indicates a hazardous situation which, if not avoided, will result
in death or serious injury.
WARNING—Indicates a hazardous situation which, if not avoided, could
result in death or serious injury.
CAUTION—Indicates a hazardous situation which, if not avoided, could
result in minor or moderate injury.
NOTICE—Indicates a hazard that could result in property damage only
(including damage to the control).
IMPORTANT—Designates an operating tip or maintenance suggestion.
Overspeed /
Overtemperature /
Overpressure
Personal Protective
Equipment
The engine, turbine, or other type of prime mover should be
equipped with an overspeed shutdown device to protect against
runaway or damage to the prime mover with possible personal injury,
loss of life, or property damage.
The overspeed shutdown device must be totally independent of the
prime mover control system. An overtemperature or overpressure
shutdown device may also be needed for safety, as appropriate.
The products described in this publication may present risks that
could lead to personal injury, loss of life, or property damage. Always
wear the appropriate personal protective equipment (PPE) for the job
at hand. Equipment that should be considered includes but is not
limited to:

Eye Protection

Hearing Protection

Hard Hat

Gloves

Safety Boots

Respirator
Always read the proper Material Safety Data Sheet (MSDS) for any
working fluid(s) and comply with recommended safety equipment.
Start-up
Automotive
Applications
Woodward
Be prepared to make an emergency shutdown when starting the
engine, turbine, or other type of prime mover, to protect against
runaway or overspeed with possible personal injury, loss of life, or
property damage.
On- and off-highway Mobile Applications: Unless Woodward's control
functions as the supervisory control, customer should install a
system totally independent of the prime mover control system that
monitors for supervisory control of engine (and takes appropriate
action if supervisory control is lost) to protect against loss of engine
control with possible personal injury, loss of life, or property damage.
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To prevent damage to a control system that uses an alternator or
battery-charging device, make sure the charging device is turned off
before disconnecting the battery from the system.
Battery Charging
Device
Electrostatic Discharge Awareness
Electrostatic
Precautions
Electronic controls contain static-sensitive parts. Observe the
following precautions to prevent damage to these parts:

Discharge body static before handling the control (with power to
the control turned off, contact a grounded surface and maintain
contact while handling the control).

Avoid all plastic, vinyl, and Styrofoam (except antistatic versions)
around printed circuit boards.

Do not touch the components or conductors on a printed circuit
board with your hands or with conductive devices.
To prevent damage to electronic components caused by improper
handling, read and observe the precautions in Woodward manual
82715, Guide for Handling and Protection of Electronic Controls,
Printed Circuit Boards, and Modules.
Follow these precautions when working with or near the control.
1. Avoid the build-up of static electricity on your body by not wearing clothing
made of synthetic materials. Wear cotton or cotton-blend materials as much
as possible because these do not store static electric charges as much as
synthetics.
2. Do not remove the printed circuit board (PCB) from the control cabinet
unless absolutely necessary. If you must remove the PCB from the control
cabinet, follow these precautions:

Do not touch any part of the PCB except the edges.

Do not touch the electrical conductors, the connectors, or the
components with conductive devices or with your hands.

When replacing a PCB, keep the new PCB in the plastic antistatic
protective bag it comes in until you are ready to install it. Immediately
after removing the old PCB from the control cabinet, place it in the
antistatic protective bag.
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Regulatory Compliance
European Compliance for CE Marking:
These listings are limited only to those units bearing the CE Marking.
EMC Directive:
Declared to 2004/108/EC COUNCIL DIRECTIVE of 15
December 2004 on the approximation of the laws of the
Member States relating to electromagnetic compatibility and
all applicable amendments. 2004/108/EC is met by
evaluation of the physical nature to the EMC protection
requirement. Electromagnetically passive or “benign”
devices are excluded from the scope of the Directive
2004/108/EC, however they also meet the protection
requirement and intent of the directive.
Pressure
Equipment
Directive:
(Fisher Valve)
Certified to Pressure Equipment Directive 97/23/EC of 29
May 1997 on the approximation of the laws of the Member
State concerning pressure equipment, Category III, Bureau
Veritas CE-0041-PED-H-FVD-001-11-USA, Module H.
Fisher Controls International, LLC Declaration of Conformity
is provided with each Gas Stop/Ratio Valve
ATEX –
Potentially
Explosive
Atmospheres
Directive:
Declared to 94/9/EC COUNCIL DIRECTIVE of 23 March
1994 on the approximation of the laws of the Member States
concerning equipment and protective systems intended for
use in potentiallyexplosive atmospheres.
Zone 2, Category 3, Group II G, Ex nA IIC T3X Gc, IP54
See below for special conditions for safe use.
Valves with Intrinsically Safe Components—
ATEX –
Declared to 94/9/EC COUNCIL DIRECTIVE of 23 March
Potentially
1994 on the approximation of the laws of the Member States
Explosive
concerning equipment and protective systems intended for
Atmospheres
use in potentiallyexplosive atmospheres.
Directive:
Zone 2, Category 3, Group II G, Ex nA IIC T3X Gc, IP54


Special Conditions for Safe Use:
The LVDT and servo valve must be wired using barrier
wiring drawings shown in Figure 1-4.
Servo valve must not be replaced with one that has
previously been installed in ‘nA’ applications.
Other European Compliance:
Compliance with the following European Directives or standards does not qualify
this product for application of the CE Marking:
Machinery
Directive:
Compliant as partly completed machinery with Directive
2006/42/EC of the European Parliament and the Council of
17 May 2006 on machinery.
Pressure
Compliant as “SEP” per Article 3.3 to Pressure Equipment
Equipment
Directive 97/23/EC of 29 May 1997 on the approximation of
Directive:
the laws of the Member States concerning pressure
(applies to
equipment.
actuator portion
of valve assembly only)
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Gas Stop/Ratio Valve
ATEX:
Manual 26620
Exempt from the non-electrical portion of the ATEX Directive
94/9/EC due to no potential ignition sources per EN 13463-1.
Other International Compliance
TIIS:
Applicable to the servo valve and LVDT. Where customer
has requested TIIS compliance, the servo valve and LVDT
are TIIS-marked and must be installed with barriers as
shown in the Installation chapter.
GOST R:
Certified for use in explosive atmospheres within the
Russian Federation per GOST R certificate POCC US.
ГБ06.B01025 as ExnAIIT3 X.
North American Compliance:
Suitability for use in North American Hazardous Locations is the result of
compliance of the individual components:
LVDT:
CSA Certified for Class I, Divisions 1 and 2, Groups A, B, C,
D, T4,for use in the United States and Canada per CSA
151336-1090811.
OR
LVDT:
Servo Valve:
ETL Certified for Class I, Division 2, Groups A, B, C, D, T3,
per ETL J98036083-003, For use in United States and
Canada.
Certified for Class I, Division 2, Groups A, B, C, D for the
United States per FM 4B9A6.AX.
CSA Certified for Class I, Division 2, Groups A, B, C, D for
use in Canada per CSA 1072373.
Junction Box:
UL Certified for Class I, Zone 1, AEx e II, Ex e II, T6 for use
in North America per UL E203312.
Special Conditions for Safe Use—All Valves
Wiring must be in accordance with North American Class I, Division 2 or
European Zone 2, Category 3 wiring methods as applicable, except for valves
requiring intrinsically safe wiring as stated above.
Field Wiring must be suitable for at least 100 °C.
The wiring junction box provides earth ground terminals if needed for a separate
earth ground to meet wiring requirements.
T3 reflects conditions without process fluid. The surface temperature of this valve
approaches the maximum temperature of the applied process media. It is the
responsibility of the user to ensure that the external environment contains no
hazardous gases capable of ignition in the range of the process media temperatures.
Compliance with the Machinery Directive 2006/42/EC noise measurement and
mitigation requirements is the responsibility of the manufacturer of the machinery into
which this product is incorporated.
The risk of electrostatic discharge is reduced by permanent installation of the valve,
proper connection to the protective earth (PE) terminals, and care when cleaning.
The valve should not be cleaned unless the area is known to be non-hazardous.
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EXPLOSION HAZARD—Do not connect or disconnect while circuit is
live unless area is known to be non-hazardous.
Substitution of components may impair suitability for Class I,
Division 2 or Zone 2.
RISQUE D’EXPLOSION—Ne pas raccorder ni débrancher
tant que l’installation est sous tension, sauf en cas
l’ambiance est décidément non dangereuse.
La substitution de composants peut rendre ce matériel
inacceptable pour les emplacements de Classe I, Division 2
ou Zone 2.
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Gas Stop/Ratio Valve
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Gas Stop/Ratio Valve
Chapter 1.
General Information
The Woodward Gas Stop/Ratio Valve performs a dual function for industrial or
utility gas turbines. One function rapidly shuts off fuel to the turbine fuel control
system. Another function provides accurate control of gas fuel pressure at the
outlet of the stop/ratio valve. This pressure is applied to the inlets of the gas fuel
control valve.
The Gas Stop/Ratio Valve features a modular design, and meets critical control
characteristics while allowing the same valve design to accommodate a variety of
stroke, force output, and mechanical interface arrangements. The electrical and
mechanical interfaces have been designed for quick and easy assembly or
removal of the valve, at the factory or in the field. The components include an
on-board hydraulic filter, electrohydraulic servo valve, trip valve, single-acting
hydraulic cylinder, and dual LVDTs (the 6” and 8” valves also have the option for
triple LVDTs).
Optimum control of the gas turbine requires that the actuator and valve
accurately and quickly track the demand signals transmitted by the control. The
stop/ratio valve has been designed to provide output forces that exceed the
opening and closing requirements with some margin. The additional margin helps
ensure that the system moves rapidly even under service conditions where the
valve has been contaminated or worn. The hydraulic trip relay valve has been
selected to provide high operating force margins, high flow capacity, and to
ensure the desired closure rate of the valve under trip conditions.
By using a long actuation rod between the hydraulic cylinder and the valve lever
arm, the side-loading forces on the actuator shaft and seals are greatly reduced,
decreasing the wear between sliding parts, and increasing the useful service life
of the system. The ample distance between the wetted heavy-duty linear slide
rings within the stop/ratio valve accommodates any remaining side load. These
provisions provide extended service life even in severe service conditions.
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Gas Stop/Ratio Valve Functional Characteristics
Functional Requirement
Valve Type
Position Accuracy
Position Repeatability
Hydraulic Fluid Type
Maximum Operating Hydraulic
Supply Pressure
Proof Test Fluid Pressure Level
Minimum Burst Fluid Pressure
Fluid Filtration Required
Hydraulic Fluid Contamination
Level
Hydraulic Fluid Temperature
Actuator Ambient Temperature
Vibration Test Level
Gas Stop/Ratio Valve
Fisher Type Vee-Ball® Design V300 or V300 Series B or
V200 Series B Flangeless
HD Metal, TCM-Ultra, or SS-260 seals
±1% full scale (over ±25 °F/±14 °C deviation from calibration)
±0.5% of point over the range of 10 to 100%
Petroleum Based hydraulic fluids as well as fire resistant
hydraulic fluids such as Fyrquel EHC
1200 to 1700 psig (8274 to 11 722 kPa)
(design at 1600 psig/11 032 kPa)
2550 psig (20 685 kPa) minimum per SAE J214 (Prod Test)
4250 psig (34 475 kPa) minimum per SAE J214
10–15 µm at 75 Beta
Per ISO 4406 code 18/16/13 max, code 16/14/11 preferred
+80 to +170 °F (+27 to +77 °C)
–20 to +180 °F (–29 to +82 °C)
Random 0.01500 gr²/Hz from 10 to 40 Hz ramping down to
0.00015 gr²/Hz at 500 Hz (1.04 Grms)
Shock
Limited to 30 g by servo valve
Trip Time
Less than 0.200 seconds (100–0% stroke)
Open Slew Time
5 to 95% in 0.500 ±0.15 seconds
Close Slew Time
95 to 5% in 0.500 ± 0.15 seconds
Trip Pressure
Pick up 24 ±6 psid (165 ±41 kPa)
(relative to hydraulic return)
Drop out 22 ±6 psid (152 ±41 kPa)
Hydraulic Fluid Connections
Trip Relay Pressure–1.062-12 UNF straight thread port (–12)
Supply Pressure–0.750-16 UNF straight thread port (–8)
Return Port–1.312-20 UNF straight thread port (–16)
Servo Input Current Rating
–7.2 to +8.8 mA (null bias 0.8 ±0.32 mA)
Paint
Two part Epoxy
Actuation Forces
3, 4, & 6” valves 6 & 8” valves
1
2
(opening at 1200 psig/8274 kPa)
(small actuator ) (large actuator )
Opening Force
(closing via spring)
Fully Extended
811 lb/3607 N
1200 lb/5338 N
Fully Retracted
1581 lb/7032 N
3085 lb/13 722 N
Closing Force
Fully Extended
2075 lb/9230 N
4690 lb/20 861 N
Fully Retracted
1305 lb/5805 N
2805 lb/12 477 N
Design Availability Objective
Better than 99.5% over an 8760 hour period
Sound Level
Per Fisher-Rosemount Catalog 12
1
Small actuator used on 3”, 4”, and 6” valves with HD Metal or TCM-Ultra seals
2
Large actuator used on 6” valves with SS-260 seals, as well as on 8” valves with HD
Metal or TCM-Ultra seals
®
NOTE—Vee-Ball is a trademark of Fisher-Rosemount.
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Gas Stop/Ratio Valve
Figure 1-1. Gas Stop/Ratio Valve (typical; 3-inch shown)
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Figure 1-2. Single Acting Hydraulic Schematic
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Figure 1-3a. Electrical Schematic and Wiring Diagram (Dual LVDT)
Figure 1-3b. Electrical Schematic and Wiring Diagram (Triple LVDT, 6” and 8”
valves only)
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Figure 1-4a. LVDT Barrier Wiring Diagram (TIIS requirement, Japan)
[This figure applies to TIIS requirement for Japan only.]
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Figure 1-4b. Servo Valve Barrier Wiring Diagram (TIIS requirement, Japan)
[This figure applies to TIIS requirement for Japan only.]
Woodward
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Notes for Figures 1-5 through 1-11
1.
These general reference outline drawings apply to various Woodward Gas Fuel
Stop/Ratio valves. Consult Woodward for the latest outline drawing for your
particular stop/ratio valve.
2.
Installation Orientation
Pipe supported only
Orientation vertical approximately as shown
See elsewhere in this manual for other installation recommendations
3.
Approximate Weight
3” Valve—255 lbs/116 kg
4” Valve—280 lbs/127 kg,
6” Valve (except SS-260)—332 lbs/151 kg
6” Valve (SS-260)—447 lbs/203 kg
8” Valve—540 lbs/245 kg
4.
Service Manual Replacement Parts
Servo Valve—consult Woodward for part number
O-rings for servo valve—consult Woodward for part number
Filter element—consult Woodward for part number
Manual—consult Woodward for part number
LVDT—consult Woodward for part number
Trip relay valve—consult Woodward for part number
Seal kit for trip relay valve—consult Woodward for part number
5.
Description of Stop/Ratio Valve
Process fluid
natural gas
Temperature range
natural gas 50 to 300 °F/10 to 149 °C (unheated fuel)
natural gas 50 to 450 °F/10 to 232 °C (heated fuel)
ambient –20 to +180 °F/–29 to +82 °C
External leakage
(2 cm³/min maximum to overboard drain)
6.
Actuation
Cylinder bore
7.
Servo Valve
Flow rating
1
Small Actuator : 1.750 inch diameter (44.45 mm)
Large Actuator2: 2.500 inch diameter (63.50 mm)
Stroke
3.500 inch (88.90 mm)
Static seals
Elastomer per US MIL-R-83248 (Viton)
Operating fluid
Petroleum-based hydraulic fluid as well as fire resistant
hydraulic fluids such as Fyrquel EHC
Rated hydraulic pressure
1600 psig/11 032 kPa
Operating hydraulic pressure 1200 to 1700 psig/8274 to 11 722 kPa
Ambient temperature
–20 to +180 °F/–29 to +82 °C
Hydraulic fluid temperature 80 to 170 °F/27 to 77 °C
Electrical input rating
Null bias
Electrical connection
1
Small Actuator : 5.0 US gal/min (18.9 L/min) at 1000
psid (6895 kPa) valve drop, 4-way
2
Large Actuator : 10.0 US gal/min (37.8 L/min) at 1000
psid (6895 kPa) valve drop, 4-way
±8 mA (sum of three coils)
10% of rated flow to close stop/ratio valve
(= 10 ± 4% rated current at hydraulic null)
0.375 O.D. tube fitting. 0.562-18 UNF-2A thread per
MS 33656-6
1
Small actuator used on 3”, 4”, and 6” valves with HD Metal or TCM-Ultra seals
Large actuator used on 6” valves with SS-260 seals, as well as on 8” valves with HD
Metal or TCM-Ultra seals
2
These general reference outline drawings apply to various
Woodward Gas Fuel Stop/Ratio valves. Consult Woodward for the
latest outline drawing for your particular stop/ratio valve.
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Gas Stop/Ratio Valve
Figure 1-5a. Gas Stop/Ratio Valve Outline Drawing (3-inch)
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Figure 1-5b. Gas Stop/Ratio Valve Outline Drawing (3-inch)
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Figure 1-6a. Gas Stop/Ratio Valve Outline Drawing (4-inch)
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Figure 1-6b. Gas Stop/Ratio Valve Outline Drawing (4-inch)
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Figure 1-7a. Gas Stop/Ratio Valve Outline Drawing (6-inch, except SS-260)
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Figure 1-7b. Gas Stop/Ratio Valve Outline Drawing (6-inch, except SS-260)
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Figure 1-8a. Gas Stop/Ratio Valve Outline Drawing (6-inch, SS-260)
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Figure 1-8b. Gas Stop/Ratio Valve Outline Drawing (6-inch, SS-260)
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Figure 1-9a. Gas Stop/Ratio Valve Outline Drawing (6-inch, with 3 LVDTs,
SS-260)
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Figure 1-9b. Gas Stop/Ratio Valve Outline Drawing (6-inch, with 3 LVDTs,
SS-260)
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Figure 1-10a. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 2 LVDTs)
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Figure 1-10b. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 2 LVDTs)
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Figure 1-11a. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 3 LVDTs)
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Figure 1-11b. Gas Stop/Ratio Valve Outline Drawing (8-inch, with 3 LVDTs)
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Chapter 2.
Stop/Ratio Valve Operation
The Gas Stop/Ratio Valve actuator is controlled by an electronic servo-control
system (not included), which compares the demanded and actual valve positions.
The control system modulates the input current signal to the electrohydraulic
servo valve to minimize the positioning system error. See Figure 1-2 for a
functional schematic of the single acting actuator.
Hydraulic oil enters the actuator via a removable element filter with integral high
P indicator and is directed to a four way, electrohydraulic servo valve used in a
three-way configuration. The PC1 control pressure output from the servo valve is
directed to the top of the hydraulic piston. When the force exerted by the
hydraulic pressure exceeds the force of the opposing loading springs, the output
piston extends, rotating the valve in the opening direction.
A trip relay valve assembly is interposed between the electrohydraulic servo
control valve and the servo output stage. Loss or reduction of the externally
supplied trip signal pressure causes the trip relay valve to shift position. This
connects the upper cavity of the actuator piston to the hydraulic drain. The force
supplied by the return springs pushes the actuation rod up, rotating the valve to
the closed position.
Two redundant LVDT position feedback transducers are also mounted within
each actuator. An optional third LVDT is available on the 6” and 8” stop/ratio
actuators only. The LVDT sensor cores and support rods are connected to the
main actuator output rod by a coupling arrangement guided on a bushing. This
guide bushing maintains LVDT alignment to minimize core damage due to sliding
wear and the associated loss of sensing accuracy.
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Chapter 3.
Standard Component Details
Triple Coil Electrohydraulic Servo Valve Assembly
The stop/ratio valve actuator utilizes a two stage hydraulic servo valve to
modulate the position of the output shaft and thereby control the stop ratio valve.
The first stage torque motor utilizes a triple wound coil, which controls the
position of the first and second stage valves in proportion to the total electrical
current applied to the three coils.
If the control system requires a rapid movement of the valve to increase fuel
pressure to the control valves, the total current is increased well above the null
current. In such a condition, supply oil is admitted to the cavity above the
actuator piston. The flow rate delivered to the upper piston cavity is proportional
to the total current applied to the three coils. Thus, the actuator stroke velocity
and the valve opening are also proportional to the current (above null) supplied to
the torque motor above the null point.
If the control system requires a rapid movement to reduce fuel pressure
downstream of the stop/ratio valve, the total current is reduced well below the
null current. In such a condition, the actuator piston cavity is connected to the
hydraulic drain circuit. The flow rate returning from the upper piston cavity of the
valve is proportional to the magnitude of the total current below the null value.
The flow rate and closing velocity of the valve are in this case proportional to the
total current below the null point.
Near the null current, the servo valve essentially isolates the upper piston cavity
from the hydraulic supply and drain, and the upper piston pressure and spring
load are balanced to maintain a constant position. The control system, which
regulates the amount of current delivered to the coils, modulates the current
supplied to the coil to obtain proper closed loop operation of the system.
Trip Relay Valve Assembly
The stop/ratio valve utilizes a three-way, two position, hydraulically operated
valve to switch the position of the gas stop/ratio valve. When the trip circuit
pressure increases above 24 ±6 psid (165 ±41 kPa) relative to hydraulic drain
pressure, the three-way relay valve shifts position. The servo valve control port is
then connected to the actuator upper piston cavity, and this interconnecting route
is isolated from the drain passage. Actuation pressure is routed to the upper
piston cavity of the valve, allowing the gas stop/ratio actuator to function.
As the trip circuit supply pressure reduces below 22 ±6 psid (152 ±41 kPa)
relative to hydraulic drain pressure, the three-way relay valve shifts position such
that the upper piston cavity is connected to the hydraulic drain circuit, and
isolated from the hydraulic supply. As the pressure falls within the upper piston
cavity, the return spring rapidly returns the actuator piston to the upward position,
closing the stop ratio valve and shutting off fuel to the engine.
24
Woodward
Manual 26620
Gas Stop/Ratio Valve
Hydraulic Filter Assembly
The stop/ratio actuator is supplied with an integrated, high capacity filter. This
broad range filter protects the internal hydraulic control components from large
oil-borne contaminants that might cause the hydraulic components to stick or
operate erratically. The filter is supplied with a visual indicator which indicates
when the pressure differential exceeds the recommended value, indicating that
replacement of the element is necessary.
LVDT Position Feedback Sensors
The stop/ratio actuator uses dual LVDTs for position feedback. An optional third
LVDT is available on the 6” and 8” stop/ratio actuators only. The LVDTs are
factory set to give 0.7 ±0.1 Vrms feedback at minimum position and 3.5 ±0.5
Vrms feedback at maximum position. The actual voltage values for each LVDT
are recorded on a label placed inside the actuator electrical box, for reference
during field calibration.
Woodward
25
Gas Stop/Ratio Valve
Manual 26620
Chapter 4.
Installation
General
See the outline drawings (Figures 1-5 through 1-11) for:

Overall dimensions

Process piping flange locations

Hydraulic fitting sizes

Electrical connections

Lift points and center of gravity

Weight of the valve
The design of the Vee-Ball® valve requires that the rotary drive shaft be mounted
horizontally. Additionally, a vertical actuator position is generally preferred to
conserve floor space as well as ease of making electrical, fuel, and hydraulic
connections and changing the hydraulic filter element.
The stop/ratio valve is designed for support by the piping flanges alone.
Additional supports are neither needed nor recommended.
The standard stop/ratio valve is supplied with a left-hand orientation as shown in
the outline drawing. The valve can be configured with a right-hand orientation;
however, this request must be on the purchase order at the time the order is
placed for this change to take place.
External fire protection is not provided in the scope of this product. It
is the responsibility of the user to satisfy any applicable
requirements for their system.
Due to typical noise levels in turbine environments, hearing
protection should be worn when working on or around the valve.
The surface of this product can become hot enough or cold enough
to be a hazard. Use protective gear for product handling in these
circumstances. Temperature ratings are included in the specification
section of this manual.
Do not lift or handle the valve by any conduit. Lift or handle the valve
only by using the eyebolts.
The surface temperature of this valve approaches the maximum
temperature of the applied process media. It is the responsibility of
the user to ensure that the external environment contains no
hazardous gases capable of ignition in the range of the process
media temperatures.
26
Woodward
Manual 26620
Gas Stop/Ratio Valve
Unpacking
The valve is shipped in an airtight bag with desiccant to ensure a non-corrosive
environment. We recommend that the valve be kept in its shipping container until
installation. If the valve is to be stored for extended periods of time, encase the
valve in an airtight container with desiccant.
Piping Installation
Refer to ANSI B16.5 for details of flange, gasket, and bolt types and dimensions.
Verify that the process piping flange-to-flange-face dimensions meet the
requirements of the outline drawings (Figures 1-5 through 1-11) within standard
piping tolerances. The valve should mount between the piping interfaces such
that the flange bolts can be installed with only manual pressure applied to align
the flanges. Mechanical devices such as hydraulic or mechanical jacks, pulleys,
chain-falls, or similar should never be used to force the piping system to align
with the valve flanges.
The stop/ratio valve is designed for support by the piping flanges alone;
additional supports are neither needed nor recommended.
Grade 5 (metric class 8.8) bolts or studs should be used to install the valve into
the process piping. The length and diameter for Class 300 flanges shall conform
to the following table according to the valve flange size.
Nominal Pipe
Size
1 inch/
25 mm
2 inch/
51 mm
3 inch/
76 mm
4 inch/
102 mm
6 inch/
152 mm
8 inch/
203 mm
Number of
Bolts
4
8
8
8
8
12
Diameter of
Bolts
5/8 inch/
16 mm
3/4 inch/
19 mm
3/4 inch/
19 mm
3/4 inch/
19 mm
3/4 inch/
19 mm
7/8 inch/
22 mm
Stud Length
3.00 inch/
76.2 mm
3.50 inch/
88.9 mm
4.25 inch/
108.0 mm
4.50 inch/
114.3 mm
4.75 inch/
120.6 mm
5.50 inch/
139.7 mm
Machine Bolt
Length
2.50 inch/
63.5 mm
3.00 inch/
76.2 mm
3.50 inch/
88.9 mm
3.75 inch/
95.2 mm
4.25 inch/
108.0 mm
4.75 inch/
120.6 mm
Flange gasket materials should conform to ANSI B16.20. The user should select
a gasket material which will withstand the expected bolt loading without injurious
crushing, and which is suitable for the service conditions.
When installing the valve into the process piping, it is important to properly torque
the stud/bolts in the appropriate sequence in order to keep the flanges of the
mating hardware parallel to each other. A two-step torque method is
recommended. Once the studs/bolts are hand tightened, torque the studs/bolts in
a crossing pattern to half the torque value listed in the following table. Once all
studs/bolts have been torqued to half the appropriate value, repeat the pattern
until the rated torque value is obtained.
Bolt Size
5/8 inch/16 mm
3/4 inch/19 mm
7/8 inch/22 mm
Woodward
Torque
150–155 lb-ft/203–210 Nm
250–260 lb-ft/339–353 Nm
375–390 lb-ft/508–529 Nm
27
Gas Stop/Ratio Valve
Manual 26620
Hydraulic Connections
There are three hydraulic connections that must be made to each valve: supply,
return, and trip oil. The connections to the valve are straight-thread O-ring style
ports per SAE J514. The tubing up to the valve must be constructed to eliminate
any transfer of vibration or other forces into the valve.
Make provisions for proper filtration of the hydraulic fluid that will supply the
actuator. The system filtration should be designed to assure a supply of hydraulic
oil with a maximum ISO 4406 contamination level of 18/16/13 and a preferred
level of 16/14/11. The filter element included with the actuator is not intended to
provide adequate filtration over the entire life of the actuator.
The hydraulic supply to the actuator is to be 0.500 inch (12.70 mm) tubing
capable of supplying 10 US gallons/min (18 L/min) at 1200–1700 psig
(8274–11 722 kPa).
The hydraulic drain should be 1.00 inch (25.4 mm) tubing and must not restrict
the flow of fluid from the valve. The drain pressure must not exceed 30 psig (207
kPa) under any condition.
The trip relay valve supply should be 0.750 inch (19.05 mm) tubing. The Trip
Relay Pressure should be above 40 psig (276 kPa) to enable the valve to
function.
Electrical Connections
EXPLOSION HAZARD—Do not connect or disconnect while circuit is
live unless area is known to be non-hazardous.
Due to the hazardous location listings associated with this valve,
proper wire type and wiring practices are critical to operation.
Protective earth (PE) ground must be connected on the junction box
per the installation drawing to reduce the risk of electrostatic
discharge in an explosive atmosphere.
Do not connect any cable grounds to “instrument ground”, “control
ground”, or any non-earth ground system. Make all required electrical
connections based on the wiring diagram (Figures 1-3 & 1-4).
The use of cable with individually-shielded twisted pairs is recommended. All
signal lines should be shielded to prevent picking up stray signals from nearby
equipment. Installations with severe electromagnetic interference (EMI) may
require shielded cable run in conduit, double-shielded wire, or other precautions.
Connect the shields at the control system side or as indicated by the control
system wiring practices, but never at both ends of the shield such that a ground
loop is created. Wires exposed beyond the shield must be less than 2 inches
(51 mm). The wiring should provide signal attenuation to greater than 60 dB.
28
Woodward
Manual 26620
Gas Stop/Ratio Valve
Servo Valve Electrical Connection
Servo valve cable must consist of three individually shielded twisted pairs. Each
pair should be connected to one coil of the servo valve as indicated in Figures
1-3 and 1-4 (Wiring Diagram).
For valves with TIIS requirements (in Japan), the servo valve wiring
must be installed with barriers, as shown in Figure 1-4b as required
for use with the intrinsically safe method of protection.
LVDT Electrical Connection
The LVDT cable must consist of two individually shielded twisted pairs for each
LVDT. A separate pair should be used for each of the excitation voltages to each
LVDT, and a separate pair used for each of the feedback voltages from each LVDT.
For valves with TIIS requirements (in Japan), the LVDT wiring must
be installed with barriers, as shown in Figure 1-4a as required for use
with the intrinsically safe method of protection.
Fuel Vent Port
The fuel vent port must be vented to a safe location. In normal operation, this
vent should have zero leakage. However, if excessive leakage is detected from
this vent port, contact a Woodward representative for assistance.
Electronic Settings
Dynamic Tuning Parameters
It is imperative that the correct dynamic characteristics of this valve be input into
the control system to ensure that the operation of the valve/control system is
within acceptable limits.
Figure 4-1. Stop/Ratio Valve Block Diagram
Woodward
29
Gas Stop/Ratio Valve
Manual 26620
3.0 in³/sec/mA at 1600 psi supply (small actuator1);
6.0 in²/sec/mA at 1600 psi supply (large actuator1);
Ksv is proportional to square root of supply, and constant with
position.
ZetaSV =
0.7
WnSV =
680 rad/sec (108 Hz); WnSV is proportional to square root of
supply
1
1
Ac =
2.4 in² (small actuator ); 4.9 in² (large actuator )
KL =
0.80 Vrms/inch
Servo Travel =
3.5 inches
TauL =
0.005 seconds (depends on excitation/demodulation)
1
See page 2 for usage of small and large actuators
Ksv nominal =
Figure 4-2. Structures for PID Control
Control
Gain Settings
Proportional
Control
Kp=5;
Proportional
Integral
Kp=3; Ki=5;
Proportional
Integral
Derivative
Kp=3; Ki=5;
Kd=0.01 or
Tau Lead = 0.01
Table 3-1. Recommended Control Gain Values for Different Control Types
Null Current Adjustment
Every valve shipped contains documentation that gives the actual Null Current as
measured by Woodward. It is imperative that the control system null current
match the as-measured current for each valve in the system. Incorrect null
current setting, with proportional control only, will result in position error.
Rigging Procedure
Inside the electrical enclosure of the valve, there is an adhesive label that
contains the appropriate valve position (as a percent of full stroke), the physical
stroke (inches), and the corresponding LVDT feedback signals for each LVDT
(assuming 7.0 Vrms excitation at 3000 Hz).
Once the control system is connected to the valve and control of the valve is
established, set the valve command position to 0% of full stroke. Measure the
feedback voltage from each LVDT. Adjust the Offset in the feedback loop until the
feedback voltage matches the documented values (see the label inside the electrical
enclosure) for that position. Adjust the command position to 100% of full stroke.
Adjust the Gain of the feedback loop until the LVDT feedback voltage matches the
documented values. Set the command position to close the valve. Verify that the
valve is closed visually and that the feedback voltage from the LVDT is 0.7 ± 0.1
Vrms. This process may have to be repeated to ensure the feedback voltages at
both the 0% and 100% command positions match the documented values.
30
Woodward
Manual 26620
Gas Stop/Ratio Valve
Chapter 5.
Maintenance and Hardware Replacement
Maintenance
Any cleaning by hand or with water spray must be performed while
the area is known to be non-hazardous to prevent an electrostatic
discharge in an explosive atmosphere.
The Gas Stop/Ratio Valve requires no maintenance or adjustment in preparation
for or during normal operation.
Woodward recommends routine checks of the DP gauge on the filter assembly to
verify that the filter is not partially clogged. If the DP indicator shows red, the filter
element needs to be replaced.
In the event that any of the standard components of the valve become
inoperative, field replacement of certain components is possible. Contact a
Woodward representative for assistance.
Hardware Replacement
To prevent possible serious personal injury, or damage to equipment,
be sure all electric power, hydraulic pressure and gas pressure have
been removed from the valve and actuator before beginning any
maintenance or repairs.
EXPLOSION HAZARD—Do not connect or disconnect while circuit is
live unless area is known to be non-hazardous.
Substitution of components may impair suitability for Class I,
Division 2 or Zone 2.
External fire protection is not provided in the scope of this product. It
is the responsibility of the user to satisfy any applicable
requirements for their system.
Do not lift or handle the valve by any conduit. Lift or handle the valve
only by using the eyebolts.
Due to typical noise levels in turbine environments, hearing
protection should be worn when working on or around the Gas
Stop/Ratio valve.
The surface of this product can become hot enough or cold enough
to be a hazard. Use protective gear for product handling in these
circumstances. Temperature ratings are included in the specification
section of this manual.
See the outline drawings (Figures 1-5 through 1-11) for the location of items.
Woodward
31
Gas Stop/Ratio Valve
Manual 26620
Hydraulic Filter Assembly/Cartridge
The hydraulic filter is located on the hydraulic manifold, hanging directly under
the servo valve.
Replacement of Filter Assembly
1. Remove four 0.312-18 UNC socket head cap screws.
2. Remove the filter assembly from manifold block.
The filter contains a large amount of hydraulic fluid that may be
spilled during filter removal.
3. Remove the two O-rings present in the interface between the filter and the
manifold.
4. Obtain a new filter assembly.
5. Place two new O-rings in the new filter assembly.
6. Install filter onto manifold assembly. Be sure to place the filter in the correct
orientation. See the outline drawings (Figures 1-5 through 1-11).
7. Install four 0.312-18 cap screws through filter and torque into manifold to
244–256 lb-in (27.6–28.9 Nm).
Replacement of Filter Cartridge
The filter contains a large amount of hydraulic fluid that may be
spilled during filter removal.
1. Using a 1-5/16 inch (~33+ mm) wrench, loosen the bowl from the filter
assembly.
2. Remove the filter element by pulling it downward.
3. Obtain a new filter element.
4. Lubricate the O-ring on the ID of the cartridge with hydraulic fluid.
5. Install the cartridge into the assembly by sliding the open end of the cartridge
upward onto the nipple.
6. Install the filter bowl. Tighten only by hand.
Trip Relay Valve Cartridge
The trip relay valve cartridge is located in the hydraulic manifold block.
Hydraulic fluid may spill during cartridge removal.
1. Using a 1.5 inch (~38+ mm) wrench, loosen the trip relay valve from the
hydraulic manifold.
2. Slowly remove the cartridge from the manifold.
3. Obtain new trip relay valve cartridge and verify part number and revision with
existing unit.
4. Verify that all O-rings and backup rings are present on new cartridge.
5. Lubricate O-rings with hydraulic fluid or petroleum jelly.
6. Install cartridge into manifold housing.
7. Torque to 80–90 lb-ft (108–122 Nm).
32
Woodward
Manual 26620
Gas Stop/Ratio Valve
Servo Valve
The servo valve is located on the hydraulic manifold directly above the filter
assembly. Refer to the outline drawings (Figures 1-5 through 1-11).
There could be a substantial amount of hydraulic fluid upon removal.
1. Remove the cover to the electrical junction box.
2. Disconnect the servo valve wires from the connector blocks, as shown in the
wiring diagram (Figure 1-3a or 1-3b).
3. Loosen the conduit fittings from the electrical box and the servo valve.
4. Carefully remove the conduit from the servo valve and pull the wiring out of
the conduit.
5. Remove the four #10-32 UNF socket head cap screws holding the servo
valve to the manifold.
6. Discard the eight O-rings between the servo valve, the adapter plate, and the
manifold.
7. Obtain replacement servo valve and verify part number and revision with
existing unit.
8. Place four new O-rings on the adapter plate.
9. Reposition adapter plate onto hydraulic manifold ensuring hydraulic
passages and bolt holes are aligned correctly. Be sure that all four O-rings
remain in their proper location during assembly on the lower side of the
adaptor plate facing the manifold.
10. Remove protective plate from replacement servo valve and verify that
O-rings are on all four counter bores of the servo valve.
11. Place the servo valve onto the adapter plate that has been positioned on the
hydraulic manifold. Be sure to orient the servo valve to match the original
orientation. Be sure that all four O-rings remain in their proper location during
assembly.
12. Install four #10-32 UNF socket head cap screws and torque to 32–35 lb-in
(3.6–4.0 Nm).
13. Install the servo valve wiring through conduit and into electrical box.
14. Connect conduit to servo valve and torque to 450–550 lb-in (51–62 Nm).
15. Torque conduit to electrical box to 450–550 lb-in (51–62 Nm).
16. Install wires into servo valve connector blocks as shown in the wiring
diagram (Figure 1-3a or 1-3b). If it is necessary to cut wires for installation,
be sure to retain at least one service loop of wiring.
17. Replace cover onto junction box and tighten screws.
LVDT Replacement
To prevent possible personal injury, do NOT remove the spring cover
(which is spring-loaded to over 1000 lbs/4448 N).
The LVDTs are located on the upper mounting plate located on the top of the
large spring cylinder and below the hydraulic manifold. Refer to the outline
drawings (Figures 1-5 through 1-11).
1.
2.
3.
4.
Woodward
Remove the cover to the electrical junction box.
Disconnect each set of LVDT wires from the connector blocks.
Loosen the conduit fittings from the electrical box and from each LVDT.
Carefully remove the conduit from the LVDTs and pull the wiring out of the
conduit.
33
Gas Stop/Ratio Valve
Manual 26620
5. Disconnect the hydraulic drain connection for improved working space.
There could be a substantial amount of hydraulic fluid upon removal.
6. Remove the 0.500-20 UNF mounting nut from the defective LVDT only.
7. Remove the two 0.250-20 UNC socket head cap screws holding the LVDT
bracket to the upper mounting plate.
8. Carefully remove the LVDT assembly from the valve by lifting vertically
upwards. Take care not to damage the good LVDT housing and rod.
9. Remove the four #10-32 UNF screws holding the access cover on the side of
the spring cylinder to gain access to the LVDT rods.
10. Remove 0.375-24 UNF jam nut from defective LVDT rod.
11. Remove the defective LVDT rod using the 0.250 inch flats at the top of the
threads. The rod will be difficult to unscrew due to the thread-locking feature
incorporated into the spring plate.
12. Obtain replacement LVDT and verify part number and revision with existing
unit.
13. Install replacement LVDT rod into spring plate, positioning the rod height to
approximately match the other LVDT rod height.
14. Install the 0.375-24 UNF jam nut onto the LVDT rod but do not torque nut at
this time.
15. Carefully slide replacement LVDT through upper mounting plate and over the
LVDT rod. Be very careful not to force the LVDT at any time since this could
damage the LVDT rod.
16. Carefully reinstall the good LVDT and bracket assembly through upper
mounting plate and over the LVDT rod. Be very careful not to force the LVDT
at any time since this could damage the LVDT rod.
17. Install the two 0.250-20 UNC socket head cap screws holding the LVDT
bracket to the upper mounting plate and torque to 58–78 lb-in (6.6–8.8 Nm).
18. Install replacement LVDT into mounting bracket and torque 0.500-20 UNF
mounting nut to 400–500 lb-in (45–56 Nm).
19. Mark the LVDT wire sets so that each set of LVDT wires is distinct. Once the
LVDT wires are installed into the electrical box, it will be difficult to distinguish
the sets if they are not marked.
20. Install wiring through conduit and into electrical box.
21. Connect conduit to LVDTs and torque to 450–550 lb-in (51–62 Nm).
22. Torque conduit to electrical box to 450–550 lb-in (51–62 Nm).
23. Install wires into LVDT connector blocks as shown in the wiring diagram
(Figure 1-3a or 1-3b). If it is necessary to cut wires for installation, be sure to
retain at least one service loop of wiring.
24. Reattach the hydraulic drain connection.
25. Once the LVDT is installed, it must then be calibrated as described below.
LVDT Calibration
1. Whenever an LVDT is replaced, or whenever its core rod adjustment is
disturbed, the LVDT output voltage must be calibrated in the following way.
Use care and follow all instructions after removal of the spring
access cover. Internal components can potentially crush fingers, and
some components are held under significant force.
2. Shut off the hydraulic supply to the stop/ratio actuator.
3. Remove the access cover from the side of the stop/ratio actuator housing by
removing the four #10-32 UNF screws and washers, exposing the LVDT core
rod adjustment.
34
Woodward
Manual 26620
Gas Stop/Ratio Valve
4. Adjust the LVDT rod so that the output of the replaced LVDT is 0.7 ± 0.1
Vrms with the stop/ratio actuator fully retracted (gas valve fully closed).
5. Tighten the 1.375-24 UNF LVDT rod jam nut to 270–320 lb-in (31–36 Nm).
6. Install the stroke measurement attachment bar (Woodward part number
1327-945 provided with the stop/ratio actuator) to the moving plate of the
actuator as shown in Figure 5-1.
7. Attach an accurate stroke measurement device (dial indicator or equivalent),
capable of measuring 4 inches (100 mm) of stroke, to the stop/ratio actuator
body. Position the indicator plunger tip on the measurement bar, as shown in
Figure 5-1.
8. Apply hydraulic pressure to the stop/ratio actuator and manually command
the actuator to stroke 3.500 ± 0.005 inches (88.90 ± 0.13 mm) by
manipulating the electronic controller.
9. Note and record the LVDT output voltages at this 3.5 inch stroke position.
10. Remove the actuator control command, returning the actuator to its rest (gas
valve closed) position.
11. Shut off the stop/ratio actuator hydraulic supply.
12. Update the stop/ratio control logic with the new LVDT output voltage value.
13. Remove the cover on the stop/ratio actuator electrical junction box.
14. Replace the original LVDT max output voltage value on the label in the
stop/ratio actuator electrical junction box with the newly measured value.
15. Replace the cover on the junction box and tighten the screws.
16. Remove the dial indicator and measurement bar.
Figure 5-1. Stroke Measurement Attachment Bar
17. Reinstall the access cover with four #10-32 UNF screws, adjusting the closed
indicator mark to align with the position indicator screw slot. Tighten the four
cover attaching screws to 30–40 lb-in (3.4–4.5 Nm).
Woodward
35
Gas Stop/Ratio Valve
Manual 26620
Troubleshooting Charts
Faults in the fuel control or governing system are often associated with speed
variations of the prime mover, but such speed variations do not always indicate
fuel control or governing system faults. Therefore, when improper speed
variations occur, check all components including the engine or turbine for proper
operation. Refer to applicable electronic control manuals for assistance in
isolating the trouble. The following steps describe troubleshooting for the gas fuel
stop/ratio valve.
Disassembly of the gas fuel stop/ratio valve in the field is not recommended due
to the dangerous forces contained in the springs. Under unusual circumstances
where disassembly becomes necessary, all work and adjustments should be
made by personnel thoroughly trained in the proper procedures.
When requesting information or service help from Woodward, it is important to
include the part number and serial number of the valve assembly in your
communication.
Symptom
External hydraulic
leakage
Internal hydraulic
leakage
External gas fuel
leakage
Possible Causes
Static O-ring seal(s)
missing or deteriorated
Dynamic O-ring seal
missing or deteriorated
Servo valve internal
O-ring seal(s) missing or
deteriorated
Servo valve metering
edges worn
Piston seal missing or
deteriorated
Piping flange gaskets
missing or deteriorated
Piping flanges improperly
aligned
Piping flange bolts
improperly torqued
Internal gas fuel
leakage
36
Packing follower needs
adjustment
Packing missing or
deteriorated
Vee-Ball seal missing or
deteriorated
Remedies
Replace O-rings fitted to userserviceable components (filter, servo
valve, trip relay valve) as needed.
Otherwise, return actuator to
Woodward for service.
Return actuator to Woodward for
service.
Replace servo valve.
Replace servo valve.
Return actuator to Woodward for
service.
Replace gaskets.
Rework piping as needed to achieve
alignment requirements detailed in
Chapter 4.
Rework bolts as needed to achieve
torque requirements detailed in Chapter
4.
Adjust follower per Fisher manual Form
5290, Type Vee-Ball.
Service packing per Fisher manual
Form 5290, Type Vee-Ball.
Service seal per Fisher manual Form
5290, Type Vee-Ball, and Fisher Errata
Sheet Type Vee-Ball SS-260.
Woodward
Manual 26620
Symptom
Valve will not
open
Gas Stop/Ratio Valve
Possible Causes
Servo valve command
current incorrect. (The
sum of the current through
the three coils of the servo
valve must be greater
than the null bias of the
servo valve for the gas
valve to open.)
Servo valve failure
Hydraulic supply pressure
inadequate
Trip relay pressure
inadequate
Vee-Ball jammed
Valve will not
close
Servo valve command
current incorrect. (The
sum of the current through
the three coils of the servo
valve must be less than
the null bias of the servo
valve for the gas valve to
close.)
Servo valve failure
LVDT failure
Springs broken
Linkage broken
Vee-Ball jammed
Valve will not
respond smoothly
Hydraulic filter clogged
Servo valve spool sticking
Servo valve internal pilot
filter clogged
Excessive friction in
Vee-Ball assembly
Rod-end(s) worn out
Piston seal worn out
Actuator seals
wear out
prematurely
Hydraulic contamination
level is excessive
System is oscillating (seal
life is proportional to
distance traveled). Even
small oscillations (on the
order of ±1%) at slow
frequencies (on the order
of 0.1 Hz) cause wear to
accumulate rapidly.
Woodward
Remedies
Trace and verify that all wiring is in
accordance with the electrical
schematic (Figures 1-3a, 1-3b, or 1-4b)
and the GE system wiring schematic(s).
Pay special attention to the polarity of
the wiring to the servo valve and LVDT.
Replace servo valve.
Supply pressure must be greater than
1200 psig/8274 kPa (1600 psig/11 032
kPa preferred).
Trip pressure must be greater than 40
psig (276 kPa).
Service Vee-Ball per Fisher manual
Form 5290, Type Vee-Ball.
Trace and verify that all wiring is in
accordance with the electrical
schematic (Figures 1-3a, 1-3b, or 1-4b)
and the GE system wiring schematic(s).
Pay special attention to the polarity of
the wiring to the servo valve and LVDT.
Replace servo valve.
Replace LVDT.
Return actuator to Woodward for
service.
Return actuator to Woodward for
service.
Service Vee-Ball per Fisher manual
Form 5290, Type Vee-Ball.
Check the differential pressure indicator
on the filter housing.
Verify hydraulic contamination levels
are within recommendations of Chapter
1. The use of dither may improve
performance in contaminated systems.
Replace servo valve.
Service Vee-Ball per Fisher manual
Form 5290, Type Vee-Ball, and Fisher
Errata Sheet Type Vee-Ball SS-260.
Return actuator to Woodward for
service.
Return actuator to Woodward for
service.
Verify hydraulic contamination levels
are within recommendations of Chapter
1. The use of excessive dither may
reduce life in contaminated systems.
Determine and eliminate the root cause
of oscillation.
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Chapter 6.
Service Options
Product Service Options
If you are experiencing problems with the installation, or unsatisfactory
performance of a Woodward product, the following options are available:

Consult the troubleshooting guide in the manual.

Contact the manufacturer or packager of your system.

Contact the Woodward Full Service Distributor serving your area.

Contact Woodward technical assistance (see “How to Contact Woodward”
later in this chapter) and discuss your problem. In many cases, your
problem can be resolved over the phone. If not, you can select which course
of action to pursue based on the available services listed in this chapter.
OEM and Packager Support: Many Woodward controls and control devices are
installed into the equipment system and programmed by an Original Equipment
Manufacturer (OEM) or Equipment Packager at their factory. In some cases, the
programming is password-protected by the OEM or packager, and they are the best
source for product service and support. Warranty service for Woodward products
shipped with an equipment system should also be handled through the OEM or
Packager. Please review your equipment system documentation for details.
Woodward Business Partner Support: Woodward works with and supports a
global network of independent business partners whose mission is to serve the
users of Woodward controls, as described here:

A Full Service Distributor has the primary responsibility for sales, service,
system integration solutions, technical desk support, and aftermarket
marketing of standard Woodward products within a specific geographic area
and market segment.

An Authorized Independent Service Facility (AISF) provides authorized
service that includes repairs, repair parts, and warranty service on Woodward's
behalf. Service (not new unit sales) is an AISF's primary mission.

A Recognized Engine Retrofitter (RER) is an independent company that
does retrofits and upgrades on reciprocating gas engines and dual-fuel
conversions, and can provide the full line of Woodward systems and
components for the retrofits and overhauls, emission compliance upgrades,
long term service contracts, emergency repairs, etc.

A Recognized Turbine Retrofitter (RTR) is an independent company that
does both steam and gas turbine control retrofits and upgrades globally, and
can provide the full line of Woodward systems and components for the
retrofits and overhauls, long term service contracts, emergency repairs, etc.
You can locate your nearest Woodward distributor, AISF, RER, or RTR on our
website at:
www.woodward.com/directory
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Gas Stop/Ratio Valve
Woodward Factory Servicing Options
The following factory options for servicing Woodward products are available
through your local Full-Service Distributor or the OEM or Packager of the
equipment system, based on the standard Woodward Product and Service
Warranty (5-01-1205) that is in effect at the time the product is originally shipped
from Woodward or a service is performed:

Replacement/Exchange (24-hour service)

Flat Rate Repair

Flat Rate Remanufacture
Replacement/Exchange: Replacement/Exchange is a premium program
designed for the user who is in need of immediate service. It allows you to
request and receive a like-new replacement unit in minimum time (usually within
24 hours of the request), providing a suitable unit is available at the time of the
request, thereby minimizing costly downtime. This is a flat-rate program and
includes the full standard Woodward product warranty (Woodward Product and
Service Warranty 5-01-1205).
This option allows you to call your Full-Service Distributor in the event of an
unexpected outage, or in advance of a scheduled outage, to request a
replacement control unit. If the unit is available at the time of the call, it can
usually be shipped out within 24 hours. You replace your field control unit with
the like-new replacement and return the field unit to the Full-Service Distributor.
Charges for the Replacement/Exchange service are based on a flat rate plus
shipping expenses. You are invoiced the flat rate replacement/exchange charge
plus a core charge at the time the replacement unit is shipped. If the core (field
unit) is returned within 60 days, a credit for the core charge will be issued.
Flat Rate Repair: Flat Rate Repair is available for the majority of standard
products in the field. This program offers you repair service for your products with
the advantage of knowing in advance what the cost will be. All repair work carries
the standard Woodward service warranty (Woodward Product and Service
Warranty 5-01-1205) on replaced parts and labor.
Flat Rate Remanufacture: Flat Rate Remanufacture is very similar to the Flat
Rate Repair option with the exception that the unit will be returned to you in “likenew” condition and carry with it the full standard Woodward product warranty
(Woodward Product and Service Warranty 5-01-1205). This option is applicable
to mechanical products only.
Returning Equipment for Repair
If a control (or any part of an electronic control) is to be returned for repair,
please contact your Full-Service Distributor in advance to obtain Return
Authorization and shipping instructions.
When shipping the item(s), attach a tag with the following information:

return authorization number;

name and location where the control is installed;

name and phone number of contact person;

complete Woodward part number(s) and serial number(s);

description of the problem;

instructions describing the desired type of repair.
Woodward
39
Gas Stop/Ratio Valve
Manual 26620
Packing a Control
Use the following materials when returning a complete control:

protective caps on any connectors;

antistatic protective bags on all electronic modules;

packing materials that will not damage the surface of the unit;

at least 100 mm (4 inches) of tightly packed, industry-approved packing
material;

a packing carton with double walls;

a strong tape around the outside of the carton for increased strength.
To prevent damage to electronic components caused by improper
handling, read and observe the precautions in Woodward manual
82715, Guide for Handling and Protection of Electronic Controls,
Printed Circuit Boards, and Modules.
Replacement Parts
When ordering replacement parts for controls, include the following information:

the part number(s) (XXXX-XXXX) that is on the enclosure nameplate;

the unit serial number, which is also on the nameplate.
Engineering Services
Woodward offers various Engineering Services for our products. For these services,
you can contact us by telephone, by email, or through the Woodward website.

Technical Support

Product Training

Field Service
Technical Support is available from your equipment system supplier, your local FullService Distributor, or from many of Woodward’s worldwide locations, depending
upon the product and application. This service can assist you with technical
questions or problem solving during the normal business hours of the Woodward
location you contact. Emergency assistance is also available during non-business
hours by phoning Woodward and stating the urgency of your problem.
Product Training is available as standard classes at many of our worldwide
locations. We also offer customized classes, which can be tailored to your needs
and can be held at one of our locations or at your site. This training, conducted
by experienced personnel, will assure that you will be able to maintain system
reliability and availability.
Field Service engineering on-site support is available, depending on the product
and location, from many of our worldwide locations or from one of our FullService Distributors. The field engineers are experienced both on Woodward
products as well as on much of the non-Woodward equipment with which our
products interface.
For information on these services, please contact us via telephone, email us, or
use our website: www.woodward.com.
40
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Manual 26620
Gas Stop/Ratio Valve
How to Contact Woodward
For assistance, call one of the following Woodward facilities to obtain the address
and phone number of the facility nearest your location where you will be able to
get information and service.
Electrical Power Systems
Engine Systems
Turbine Systems
Facility---------------- Phone Number
Brazil ------------- +55 (19) 3708 4800
China ----------- +86 (512) 6762 6727
Germany--------- +49 (0) 21 52 14 51
India --------------- +91 (129) 4097100
Japan -------------- +81 (43) 213-2191
Korea -------------- +82 (51) 636-7080
Poland--------------- +48 12 295 13 00
United States ---- +1 (970) 482-5811
Facility---------------- Phone Number
Brazil ------------- +55 (19) 3708 4800
China ----------- +86 (512) 6762 6727
Germany------- +49 (711) 78954-510
India --------------- +91 (129) 4097100
Japan -------------- +81 (43) 213-2191
Korea -------------- +82 (51) 636-7080
The Netherlands - +31 (23) 5661111
United States ---- +1 (970) 482-5811
Facility---------------- Phone Number
Brazil ------------- +55 (19) 3708 4800
China ----------- +86 (512) 6762 6727
India --------------- +91 (129) 4097100
Japan -------------- +81 (43) 213-2191
Korea -------------- +82 (51) 636-7080
The Netherlands - +31 (23) 5661111
Poland--------------- +48 12 295 13 00
United States ---- +1 (970) 482-5811
You can also locate your nearest Woodward distributor or service facility on our
website at:
www.woodward.com/directory
Technical Assistance
If you need to telephone for technical assistance, you will need to provide the following information.
Please write it down here before phoning:
Your Name
Site Location
Phone Number
Fax Number
Engine/Turbine Model Number
Manufacturer
Number of Cylinders (if applicable)
Type of Fuel (gas, gaseous, steam, etc)
Rating
Application
Control/Governor #1
Woodward Part Number & Rev. Letter
Control Description or Governor Type
Serial Number
Control/Governor #2
Woodward Part Number & Rev. Letter
Control Description or Governor Type
Serial Number
Control/Governor #3
Woodward Part Number & Rev. Letter
Control Description or Governor Type
Serial Number
If you have an electronic or programmable control, please have the adjustment setting positions or
the menu settings written down and with you at the time of the call.
Woodward
41
Gas Stop/Ratio Valve
Manual 26620
Revision History
Changes in Revision D—

Updated ATEX information (page v)

Updated Declaration
Changes in Revision C—

Added warnings required by ATEX changes (pages vi, 28, 31)

Updated Declaration
Changes in Revision B—

Updated Pressure Equipment Directive and GOST R information

Updated Declaration of Conformity
Changes in Revision A—

Corrected filter torque page 32
42
Woodward
Manual 26620
Gas Stop/Ratio Valve
Declarations
Woodward
43
Gas Stop/Ratio Valve
44
Manual 26620
Woodward
Manual 26620
Woodward
Gas Stop/Ratio Valve
45
We appreciate your comments about the content of our publications.
Send comments to: [email protected]
Please reference publication 26620D.
PO Box 1519, Fort Collins CO 80522-1519, USA
1000 East Drake Road, Fort Collins CO 80525, USA
Phone +1 (970) 482-5811  Fax +1 (970) 498-3058
Email and Website—www.woodward.com
Woodward has company-owned plants, subsidiaries, and branches,
as well as authorized distributors and other authorized service and sales facilities throughout the world.
Complete address / phone / fax / email information for all locations is available on our website.
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