Description
Woodward GS6 9908-1544
Product Introduction
The Woodward GS6 9908-1544 is an electrically actuated gas fuel metering valve designed for industrial gas turbine fuel control. It belongs to the GS6 family of gas valves, which combines the fuel-metering mechanism, electric actuator, position feedback resolver, and electronic driver into one integrated assembly. Woodward identifies 9908-1544 specifically as the GS6 version with a 0.60 in² metering port and single resolver. The valve is intended for applications such as gas-turbine power generation, compressor drives, and mechanical-drive systems where the fuel control system requires accurate modulation of gaseous fuel flow.
The Woodward GS6 9908-1544 uses a spherical metering element and precision-machined port to control effective gas-flow area. The integrated driver provides closed-loop valve-position control from a 4–20 mA demand signal or supported DeviceNet/CANopen communication. Actual valve position can be returned through the corresponding interface, while dedicated shutdown and fault functions provide additional control-system integration. The driver also monitors conditions including input-signal range, resolver wiring, input power, position error, actuator faults, internal driver faults, and overcurrent.
The Woodward GS6 9908-1544 should be treated as a complete fuel-control assembly rather than simply as an actuator. The 0.60 in² port size directly affects fuel-flow capacity and pressure-drop characteristics, while the single-resolver configuration defines the feedback arrangement. Woodward’s catalog places 9908-1544 between the 0.45 in² and 0.75 in² GS6 configurations, so substituting another GS6 based only on physical appearance can change turbine fuel-flow characteristics.
Technical Specifications
| Parameter | Specification |
|---|---|
| Product Model | GS6 9908-1544 |
| Manufacturer | Woodward |
| Product Family | GS6 Gas Fuel Valve |
| Product Type | Gas Fuel Metering Valve with Onboard Driver |
| Valve Actuation | Electric |
| Metering Port | 0.60 in² |
| Equivalent Port Area | Approximately 387 mm² |
| Resolver Configuration | Single resolver |
| Gas Flow Range | 4.5–6,800 kg/h, application dependent |
| Gas Supply Pressure | 690–5,170 kPa / 100–750 psig |
| Recommended Minimum Pressure Differential | 138 kPa / 20 psid |
| Maximum Pressure Differential | 5,170 kPa / 750 psid |
| Recommended Gas Filtration | 25 µm absolute |
| Valve Leakage | 0.1% of rated flow maximum |
| Flow Turn-Down Ratio | Greater than 100:1 |
| Position Loop | Closed-loop electronic control |
| Control Input | 4–20 mA and/or DeviceNet/CANopen |
| Position Feedback | 4–20 mA and/or DeviceNet/CANopen |
| Shutdown Input | Independent remote shutdown |
| Fault Output | Valve/driver fault output |
| Driver Supply | 18–32 VDC |
| Environmental Rating | IP56 |
| Ambient Temperature | Up to approximately +93°C, configuration dependent |
| Documentation | Product Specification 03256; Manual 26171 |
The flow range is not a guaranteed flow rate for every installation. Actual gas throughput depends on gas composition, supply pressure, pressure differential, temperature, valve calibration, and turbine operating conditions. Woodward’s documentation also specifies a 25 µm absolute filtration recommendation for the fuel supply.
Woodward GS6 9908-1544
Main Features and Engineering Considerations
Integrated Electric Actuation
The GS6 combines the metering valve and electronic actuator driver in one assembly. This eliminates much of the external interconnection normally required between a separate actuator and valve controller. The onboard driver performs closed-loop position control based on the commanded valve position.
0.60 in² Metering Port
The 0.60 in² port is one of the most important identification characteristics of 9908-1544. Woodward offers the GS6 with several port areas, including 0.30, 0.45, 0.60, and 0.75 in² configurations. The port geometry directly influences the valve’s flow characteristic and pressure drop. A different port size should therefore not be considered a functionally equivalent substitute without checking the turbine fuel-system calculation.
Resolver-Based Position Feedback
The 9908-1544 is specified with a single resolver. The resolver provides the feedback required by the onboard position-control system. Resolver wiring should be checked carefully during maintenance because open circuits, shorts, incorrect termination, or degraded connections can produce position faults even when the actuator itself is mechanically healthy.
4–20 mA and Digital Control
The GS6 driver can interface with turbine control systems through a 4–20 mA control/feedback arrangement or through DeviceNet/CANopen. Woodward also describes configurations capable of accepting both analog and digital demand signals for redundant control arrangements. The actual communication and redundancy configuration should be verified against the valve’s build documentation rather than assumed solely from the GS6 family name.
Independent Shutdown
The valve includes an independent remote shutdown input. This is important in turbine protection architecture because fuel shutoff/control requirements are not identical to ordinary positioning commands. The shutdown circuit should be checked as part of turbine commissioning and trip-system testing.
Driver Diagnostics
The onboard driver monitors analog input range, resolver wiring, input power, position error, internal driver faults, actuator open/short conditions, and driver overcurrent. These diagnostics can substantially reduce troubleshooting time, but they do not eliminate the need to verify fuel pressure, wiring, mechanical travel, and turbine-control logic.
Fuel Cleanliness
The GS6’s metering element is designed for self-cleaning shear-type operation, but this does not mean contaminated fuel can be ignored. Woodward specifies 25 µm absolute filtration. Contamination, condensate, or debris can affect valve performance and fuel-system behavior even when the electronic driver reports normal operation.
Application Scenarios
Industrial Gas Turbines
The primary application is precise gaseous-fuel metering on industrial gas turbines used for electrical generation.
Compressor Drives
The GS6 can be used in gas-turbine-driven compressor systems where fuel demand must be regulated according to turbine speed, load, and operating conditions.
Mechanical Drive Turbines
Industrial mechanical-drive turbines can use the GS6 as part of the turbine’s fuel-control system.
Dry Low Emission Systems
Woodward documentation describes GS6 valves as suitable for single-valve and multiple-valve arrangements, including applications associated with Dry Low Emission turbine systems.
Turbine Retrofit and Maintenance
The 9908-1544 is particularly relevant when maintaining an installed GS6-based fuel-control system where preserving the original port size, resolver arrangement, driver interface, and fuel-flow characteristics is important.
Engineer’s Guide: Field Pitfalls
1. Do not substitute by GS6 family alone.
9908-1544 is specifically a 0.60 in², single-resolver configuration. A 0.45 or 0.75 in² version can have materially different fuel-flow behavior.
2. Check the fuel-pressure differential.
The valve requires sufficient pressure differential for accurate metering. Woodward specifies 20 psid as the recommended minimum differential for accurate flow characteristics.
3. Confirm the resolver wiring.
A resolver fault can prevent closed-loop position control even when the valve’s mechanical components appear normal.
4. Verify the 18–32 VDC driver supply.
Voltage outside the specified operating range can generate input-power faults or prevent normal valve operation.
5. Check the command interface.
Determine whether the installed turbine control system uses 4–20 mA, DeviceNet, CANopen, or a configured redundant arrangement before replacing the valve.
6. Test the independent shutdown circuit.
Do not limit commissioning to position-command testing. The remote shutdown function is part of the turbine fuel-control architecture.
7. Inspect fuel filtration.
The specified 25 µm absolute filtration should be considered part of the valve application. Contaminated gas can create mechanical problems that may initially look like an electronic control fault.
8. Do not confuse a metering valve with a shutoff valve.
The GS6 is primarily a fuel-metering/control valve. It should not automatically be treated as equivalent to a dedicated gas shutoff valve such as a GSOV.
9. Use the correct flow data.
The valve’s flow relationship depends on port geometry, gas properties, pressure, and temperature. Do not reuse another GS6 model’s flow coefficients without checking the actual valve documentation.
Frequently Asked Questions
What is Woodward 9908-1544?
It is a GS6 gas fuel metering valve with an onboard electronic driver, configured with a 0.60 in² port and single resolver.
Is 9908-1544 a PLC module?
No. It is an electrically actuated gas fuel metering valve used in industrial gas-turbine fuel-control systems.
What is the port size?
The 9908-1544 has a 0.60 in² metering port, equivalent to approximately 387 mm².
Does it have an onboard driver?
Yes. The GS6 integrates the electronic valve driver and wiring terminal box into the valve assembly.
What power supply does the driver require?
The GS6 onboard driver operates from 18–32 VDC.
What feedback does 9908-1544 use?
The exact catalog entry identifies it as a single-resolver GS6 configuration.
What control signals are supported?
The GS6 driver can interface through 4–20 mA signals and through DeviceNet/CANopen, depending on the configuration. It can also provide corresponding valve-position feedback.
What gas pressure can the GS6 handle?
The published GS6 specification gives a gas supply pressure range of approximately 690–5,170 kPa (100–750 psig), with 138 kPa (20 psid) recommended as the minimum pressure differential for accurate flow characteristics.
Which documents apply to 9908-1544?
Woodward’s catalog identifies Product Specification 03256 and Manual 26171 for the GS6 family.
Procurement Note
For Woodward GS6 9908-1544, the complete part number should be retained in the purchasing specification. The critical identification points are GS6 + 0.60 in² port + single resolver. Woodward’s official product specification confirms that the GS6 is a gas fuel metering valve with an integrated driver, while the Woodward product catalog specifically maps 9908-1544 to the 0.60 in² single-resolver configuration.
For a replacement valve, I would verify at least the port size, resolver arrangement, fuel pressure range, control interface, driver supply, shutdown wiring, flange/connection arrangement, and turbine-specific flow calibration before approving the unit.
For used or previously installed equipment, visual condition is not enough. The valve should be checked for mechanical travel, resolver response, driver diagnostics, shutdown operation, electrical insulation/connection condition, and evidence of fuel contamination before being returned to a critical turbine fuel-control circuit.
