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Woodward 9908-407
Product Name: LQ25 Liquid Fuel Metering Valve (Standard Configuration)
Product Overview: 9908-407 is a standard LQ25-series liquid fuel metering valve with an integrated electric actuator and rotary-plate valve body. It delivers high-precision closed-loop fuel flow control via a remote electronic driver, covering industrial and aeroderivative gas turbines from 1,000 kW to 42,000 kW.
Detailed content
Key Technical Specifications:
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Applicable Power Range: 1,000–42,000 kW
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Maximum Fuel Inlet Pressure: 1,200 psig (8,274 kPa)
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Maximum Fuel Bypass Pressure: 100 psig (690 kPa)
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Nominal Metering ΔP: 50 psid (345 kPa)
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Minimum Metered Flow: 80 lb/h (36 kg/h)
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Fuel Filtration: ≤20 µm
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Water Content: ≤0.1% by volume
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Solid Sediment: ≤1.0 mg/L
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Turndown Ratio: >100:1
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Metering Accuracy: ±5% of nominal flow or ±0.5% of max flow
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Full-Stroke Time: <100 ms
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Emergency Shutoff Response: <50 ms
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Drive Voltage: 18–32 VDC
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Command / Feedback: 4–20 mA
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Weight: approx. 35 kg (77 lb)
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Nominal Bore: 29.2 mm (1.15 in)
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Ingress Protection: IP66
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Operating Temperature: –28 °C to +85 °C
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Storage Temperature: –40 °C to +103 °C
Functional Features: Self-cleaning shear metering for strong anti-contamination capability. Integrated brushless DC actuator—no gear backlash, high positioning repeatability. Remote electronic driver enables valve-position closed-loop control and fault diagnostics. Standard 4–20 mA interface compatible with all control systems. No field calibration—flow is factory-characterized.
Materials & Structure: Wetted components use corrosion-resistant alloy or stainless steel; seals are FKM fluoro-carbon rubber, providing overall resistance to fuel corrosion and high-temperature aging. Frameless single-speed resolver feedback (4 VAC @ 5,000 Hz). Compact structure, terminal-block electrical interface for easy field wiring.
Working Principle: The remote driver receives 4–20 mA control signal and drives the limited-angle torque motor to rotate the metering plate, changing the effective flow area of the metering port. The built-in differential pressure regulator automatically maintains a constant 345 kPa across the port, making output flow solely a function of port opening for precise fuel metering.
Installation Requirements: Must be installed downstream of a positive-displacement pump; keep the bypass return line clear. Use standard fasteners tightened to specification torque. Shielded cable must be single-point grounded to prevent EMI from affecting signal accuracy. Mounting location should facilitate routine inspection and maintenance.
Application Scenarios: Widely applied 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 standard-compliant distillate fuels.
Usage Precautions: Fuel filtration must reach ≤20 µm to prevent metering-port wear. Regularly inspect electrical-connection tightness and cable insulation integrity. Wear hearing protection on-site—the valve body generates aerodynamic noise during operation. Avoid severe impact during storage and transport to protect the resolver and actuator.
