Woodward 9908-413

Digital guide

Product Name: LQ25 Series Standard Liquid Fuel Metering Valve

Product Introduction: This model is a standard LQ25 series liquid fuel metering valve from Woodward. As the fuel metering interface between electronic engine control systems and gas turbines, it is suitable for industrial and aeroderivative gas turbines in the 1000 kW to 42000 kW power range. The valve uses a fully electric actuator to achieve precise fuel flow regulation via a standard 4–20 mA signal.

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Technical Specifications:

Applicable power range: 1000 kW to 42000 kW
Maximum fuel inlet pressure: 1200 psig (8274 kPa)
Maximum fuel bypass pressure: 100 psig (690 kPa)
Rated metering differential pressure: 50 psid (345 kPa)
Fuel filtration accuracy: 20 microns or finer
Fuel water content limit: 0.1% by volume
Solid sediment limit: 1.0 mg/L
Minimum metering flow: 36 kg/h (80 lb/h)
Flow turn-down ratio: greater than 100:1
Operating temperature range: -28 °C to +85 °C
Storage temperature range: -40 °C to +103 °C
Valve body weight: approximately 35 kg (77 lb)
Nominal pipe diameter: 29.2 mm (1.15 in)
Protection class: IP66
Drive power supply: 18 to 32 VDC
Command signal: 4 to 20 mA
Valve position feedback signal: 4 to 20 mA

Functional Features:

Self-cleaning shear-type metering principle with strong resistance to fuel contamination
Integrated brushless DC actuator with no gear backlash and high positioning repeatability
Equipped with remote electronic driver unit for valve position closed-loop control and fault diagnosis
Standard 4–20 mA interface, compatible with various control systems
No on-site calibration required; precise flow calibration completed at factory

Application Scenarios: Widely used in liquid fuel supply systems for gas turbine power generation, mechanical drive, and marine propulsion. Compatible with diesel, JP series aviation fuel, kerosene, gasoline, and other internationally compliant distillate fuels.

Performance Parameters: Metering accuracy is ±5% of nominal flow point or ±0.5% of maximum rated flow, whichever is greater. Full-stroke slew time is less than 100 ms, and emergency shut-off response time is less than 50 ms.

Material Composition: Wetted parts are made of corrosion-resistant alloy or stainless steel; sealing components use fluorocarbon rubber (FKM); the overall structure resists fuel corrosion and high-temperature aging.

Structural Features: Uses a single-speed frameless resolver as the position feedback element, with resolver excitation parameters of 4 VAC, 5000 Hz. The valve body is compact, and the electrical interface adopts a standard terminal block design for easy on-site wiring.

Working Principle: The remote driver unit receives the 4–20 mA control signal and drives a limited-angle torque motor to rotate the rotary valve plate, changing the effective flow area of the metering port. The built-in differential pressure regulator automatically maintains a constant differential pressure of 345 kPa across the metering port, making the output flow solely dependent on the port opening and achieving precise fuel metering.

Installation Requirements:

Must be installed downstream of a positive displacement pump; the bypass return line must remain unobstructed
Valve body fixation requires compliant fasteners, tightened to specification torque
Electrical shielded cable requires single-point grounding to prevent electromagnetic interference from affecting signal accuracy
Installation location should facilitate daily inspection and maintenance operations

Usage Precautions:

Fuel filtration accuracy must reach 20 microns or finer to prevent metering port wear
Periodically inspect the tightness of electrical connections and cable insulation integrity
On-site operation generates pneumatic noise; hearing protection must be worn
Avoid severe collisions during storage and transportation to prevent damage to the resolver and actuator