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Woodward 8915-921
Product Name: 3103 Rotary Sleeve Gas Valve with EM35 Electric Actuator (Dual Resolver Configuration, 50610 Series High-End Variant)
Product Introduction: The 8915-921 is a fully electric fuel-metering assembly combining a 3103 rotary sleeve-and-shoe gas valve with an EM35 electric actuator. Its defining feature is a dual resolver redundant position-detection design, which significantly improves system reliability and safety. It is specifically intended for gas-turbine fuel-control systems where control availability is critical.
Detailed content
Technical Specifications:
- Valve Type: 3103 rotary sleeve gas valve
- Actuator Type: EM35 electric actuator with dual resolver feedback
- Gas Flow Range: 23 to 18,144 kg/h (50 to 40,000 lb/h)
- Inlet Pressure: up to 6205 kPa (900 psia); CE limited to 4964 kPa (720 psia)
- Differential Pressure: 172 to 6205 kPa (25 to 900 psi)
- Fuel Temperature: -40 to +149 °C
- Ambient Temperature: -40 to +93 °C
- Metered Fuel: Natural gas, propane, methane (specific gravity 0.5 to 1.05)
- Filtration: 25 μm absolute (β=75)
- Flow Accuracy: ±5% of point or ±0.25% of maximum flow
- Output Shaft Rotation: 60°
- Continuous Output Torque: ±24.86 N·m (±220 lb-in)
- Peak Output Torque: ±45.20 N·m (±400 lb-in)
- Motor: Brushless DC with samarium-cobalt permanent magnets
- Power Input: 28 Vdc nominal (18–32 Vdc operating range)
- Current: 25 A max for 100 ms, 15 A max continuous, ~3 A steady-state
- Torque Constant: 1.8 N·m/A
- Slew Rate: >600 °/sec
- 50° stroke actuation time: 150 ms open, 80 ms close
- Bandwidth: >5 Hz
- Position Accuracy: ±0.50° analog, ±0.10° digital
- Component Weight: ~44 kg (96 lb)
- Gas Connection: 2-inch 600# ANSI B16.5 flange
Features: Dual-resolver redundant feedback for fault tolerance; fully electric drive (no hydraulic power unit); brushless DC motor with samarium-cobalt magnets for long life; integrated fault-detection circuitry monitoring dual-resolver consistency; spring-return to minimum fuel on power loss; 4–20 mA analog or digital serial communication; flameproof cast-aluminum enclosure certified to CSA and ATEX Zone 1; self-cleaning metering geometry suited to sour-gas service.
Applications: Gas-turbine fuel systems with the highest control-availability and redundancy requirements; critical power-generation equipment; chemical-process gas turbines; dry-low-emission (DLE) high-precision control; interfaced with Woodward NetCon digital control systems.
Materials: Valve body in stainless steel; all internal moving parts of through-hardened stainless steel; actuator housing in flameproof cast aluminum; motor using samarium-cobalt permanent-magnet brushless DC technology; resolver of non-contact electromagnetic induction design; stainless-steel torsional coupling; fuel-compatible elastomeric seals.
Structure: Planetary-gear-reduction actuator directly coupled to the 3103 valve body; dual resolvers sensing metering-sleeve position; inlet guide tube with redundant seal arrangement.
Working Principle: The controller signal drives the motor to change the angular position of the valve sleeve. The dual resolvers provide closed-loop position feedback. On fault or power loss, the internal spring forces the valve to its minimum-fuel safe position.
Installation Requirements: Bolts on the flameproof cover must be torqued to specification; explosion-proof cable glands and conduit seals must be used; handling requires auxiliary lifting equipment (~44 kg); a properly grounded earthing system must be connected; fuel must be filtered to 25 μm absolute upstream of the valve inlet.
Usage Precautions: Motor cables must not be coiled; maintenance in hazardous areas requires power isolation; cable connections must be periodically inspected; surface-temperature protection must be observed; mechanical stop screws must never be adjusted; after prolonged shutdown the valve freedom of movement must be verified before start-up.
