Woodward 9907-351

Digital guide

Product Introduction: The 9907-351 is an LQ25 series electric liquid fuel metering valve designed for industrial and aero-derivative gas turbines in the 6,000 kW to 42,000 kW output range. It adopts a fully integrated all-electric design that combines a brushless DC motor, rotary plate metering valve, and non-contact position sensor, achieving precise closed-loop position control through a matched electronic driver. The LQ25 series provides self-cleaning shear-type metering, a high flow turn-down ratio, accurate flow control, and excellent corrosion resistance, serving as the core executive element of gas turbine liquid fuel electronic control systems.

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Detailed content

Technical Specifications:

Product Type: Electrically driven liquid fuel metering valve
Control Mode: Digital servo closed-loop control (with matched LQ/LO driver)
Output Form: Rotary plate angular position
Input Command Signal: 4 to 20 mA
Position Feedback Output: 4 to 20 mA
Driver Supply: 18 to 32 VDC
Operating Media: Diesel, JP series fuels, kerosene, gasoline, naphtha, gas turbine fuel oil, and other compliant distillates
Duty: Continuous modulation

Functional Features:

Fully integrated all-electric design — brushless DC motor, metering valve, and position sensor integrated in one body with no gear backlash
Self-cleaning shear-type metering via rotary plate, strong anti-pollution capability
High flow turn-down ratio exceeding 100:1
Flow accuracy of ±5% of nominal flow point or ±0.5% of maximum rated flow (whichever is greater)
Non-contact position sensing using a single- or three-speed resolver — no mechanical wear, long service life
Built-in differential pressure regulator: single-stage spring-loaded piston diaphragm type
Corrosion-resistant materials in all fuel-wetted parts
Remote driver placement up to 100 meters from the valve

Application Scenarios: Liquid fuel metering for industrial gas turbines; fuel control for aero-derivative gas turbines; fuel regulation systems for power-generation gas turbines; fuel control for mechanical-drive gas turbines; marine gas turbine liquid fuel systems; fuel metering for combined heat and power (CHP) units.

Performance Parameters:

Flow Range: 80 to 26,000 lb/h (36 to 11,794 kg/h) — the LQ25 family offers three port sizes: 0.1 in² port for 4,000 to 8,000 lb/h (1,814 to 3,629 kg/h); 0.2 in² port for 8,000 to 18,000 lb/h (3,629 to 8,165 kg/h); 0.3 in² port for 18,000 to 26,000 lb/h (8,165 to 11,794 kg/h)
Minimum Metered Flow: 80 lb/h (36 kg/h) assuming fuel specific gravity of 0.77
Maximum Fuel Inlet Pressure: 1,200 psig (8,274 kPa)
Maximum Fuel Bypass Pressure: 100 psig (690 kPa)
Regulated Differential Pressure: 50 psid (345 kPa) nominal
Full-Stroke Slew Rate: less than 0.100 s
Valve Shut-off Slew Rate: less than 50 ms
Motor Speed: 35 rad/s (typ.)
Metering Leakage: less than 80 lb/h @ 600 psig
Operating Temperature: -28°C to +103°C (-18°F to +217°F)
Storage Temperature: -40°C to +103°C (-40°F to +217°F)
Protection Rating: IP66

Material Composition:

Valve Body: High-strength aluminum alloy (standard) or stainless steel (marine environment)
Metering Plate: Corrosion-resistant hardened stainless steel, precision EDM-machined
Metering Sleeve: Integrated with motor rotor, corrosion-resistant material
Motor Housing: Aluminum alloy with cooling fins
Motor Rotor: Rare-earth permanent magnet material
Position Sensor: Single- or three-speed resolver
Differential Pressure Regulator: Spring-loaded piston diaphragm type
Seals: Fluoroelastomer (FKM)
Internal Fasteners: Stainless steel

Structural Features:

Integrated brushless DC motor co-axial with the metering valve — no gear transmission, eliminating backlash and wear
Rotary plate metering structure — metering sleeve integrated with motor rotor, single moving part for fuel metering
Hollow-shaft non-contact resolver directly detecting rotor position with no contact wear
Built-in differential pressure regulator maintaining ≈345 kPa across the metering port
Standard SAE threaded ports
Overboard drain port between dual-redundant shaft seals for leak monitoring
Standard mounting holes on valve bottom for rigid bracket mounting

Working Principle: The control system sends a 4-20 mA position command to the matched driver; the driver converts the signal into brushless DC motor drive current. The rotor drives the metering sleeve, changing the effective flow area of the metering port. The built-in differential pressure regulator maintains a constant 345 kPa across the metering port, ensuring linearity between flow and valve position. Fuel entering the valve body is partially regulated through the metering port to the turbine combustor, with the excess returning to the tank via the bypass circuit.

Installation Requirements:

Secure firmly to a rigid surface that does not exceed the vibration limits specified in the detailed specifications
Connect inlet, outlet, bypass, and overboard drain lines per the LQ25 installation drawing; the inlet receives pressurized fuel from the pump, the outlet feeds the turbine combustor(s), and the bypass returns to the fuel tank
The external overboard drain (OVBD) must be connected via rigid steel pipe to a fuel collection, purge, vent, or drain system, not exposed to blockage, physical damage, or back pressure exceeding 69 kPa (0.69 bar / 10 psig)
Driver power cable must be rated for at least 90°C and 10°C above maximum fluid and ambient temperatures

Usage Notes:

Never close the overboard drain — fuel may enter the LQ25 actuator, creating hazard potential for personal injury and/or actuator damage
Leakage above 20 cm³/min from the external drain line indicates worn or damaged shaft seal and must be investigated immediately; special tools are required for shaft seal replacement — contact Woodward
Fuel water content must be strictly controlled within 0.1% by volume to prevent internal corrosion
Periodically inspect the metering port area for abnormal wear
Do not arbitrarily change driver parameters
Replacement seals must use originally specified FKM parts