Woodward 8915-703

Digital guide

Product Name

3103 Gas Valve with EM35 Electric Actuator (3103/EM35 configuration).

Product Introduction

The 8915-703 is a Woodward configured package of the 3103 stainless steel rotary gas metering valve integrated with an EM35 electric actuator. Unlike the TM-55 hydraulic version, this configuration uses an electrically powered actuator, making it suitable for installations where a hydraulic power supply is not available or desired, while maintaining precise fuel metering for industrial gas turbine applications.

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Detailed content

Technical Specifications

Valve type: 3103 rotary sleeve-and-shoe throttling gas valve
Actuator type: EM35 electric actuator
Metered fuel: natural gas, propane, ethane, methane
Fuel specific gravity: 0.5 to 1.05
Gas flow range: 23 to 18 144 kg/h (50 to 40 000 lb/h) based on 0.6 sp gr
Inlet pressure: up to 6206 kPa (900 psia); 4964 kPa (720 psia) maximum under CE marking restriction
Differential pressure: 172 to 6206 kPa (25 to 900 psi)
Fuel temperature: -40 to +149 °C (-40 to +300 °F)
Actuator operating temperature: -40 to +121 °C (-40 to +250 °F)
Actuator type: electric, brushless DC motor with resolver position feedback
Accuracy: ±5% of point, or ±0.25% of maximum flow, whichever is larger
Hydraulic fluid: not applicable (electric actuation)
Electrical connections: per Woodward EM35 actuator installation manual

Features

Electrically driven, eliminating the need for hydraulic power supply
Brushless DC motor design for long service life
Resolver position feedback sensors provide accurate valve position indication
Soft stop spring for mechanical end-stop protection
Self-cleaning metering structure for sour gas service
Through-hardened stainless steel internal parts
Fail-safe capability through integrated design
Optional ball screw and bearing lubrication provisions for extended maintenance intervals

Application Scenarios

Industrial gas turbine generator sets without hydraulic supply
Gas turbine driven compressors
Combined heat and power (CHP) systems
Mechanical drive gas turbines
Sour gas / high sulfur fuel environments
Retrofit applications replacing hydraulic actuator packages

Performance Parameters

Flow turndown ratios up to 500:1
Maximum flow capacity depends on available gas conditions
Shearing force at sleeve outer diameter exceeds 1334 N (300 lb)
Precise positioning through resolver feedback and electric control

Material Composition

Valve body: stainless steel
Internal parts: through-hardened stainless steel
Seals: Viton (FKM) or other fuel-compatible elastomer
Actuator housing: industrial-grade alloy with corrosion protection
Ball screw and bearing assemblies: hardened steel with appropriate lubrication

Structural Characteristics

Rotary sleeve-and-shoe metering structure
EM35 electric actuator: brushless DC motor, ball screw drive, resolver feedback, soft stop spring
Two standard port configurations: 645 mm² (1 in²) and 1290 mm² (2 in²) maximum flow area
Metering sleeve support bearings positively sealed from gas
Two overboard drains on the valve body
Valve angle indicator furnished

Working Principle

The electronic control sends a command signal to the EM35 electric actuator. A brushless DC motor drives a ball screw mechanism that translates rotary motion into linear displacement, rotating the 3103 valve output shaft to position the metering sleeve. A resolver provides continuous position feedback to the control system for closed-loop accuracy. The soft stop spring protects the mechanical end stops during full-scale travel.

Installation Requirements

Handle with care; abuse can damage seals, installation surfaces, and factory adjustments
Keep protective caps on gas connections until piping is complete
Follow the Woodward EM35/3103 outline drawing for dimensions, mounting holes, and electrical conduit entries
Make all electrical connections per the Woodward electric control manuals and the EM35 actuator installation instructions
Plumb one overboard drain outside the turbine enclosure; plug the unused drain (do not plug both)
Installation attitude does not affect actuator performance
Ensure the prime mover is equipped with an independent overspeed shutdown device
Observe all plant and safety instructions; read the entire manual before installing

Usage Precautions

Observe electrostatic discharge (ESD) awareness when handling electrical connections and control electronics
Do not modify the equipment outside its specified mechanical, electrical, or operating limits
Routine maintenance requires ball screw and bearing lubrication per Woodward procedures
For servicing, use Woodward factory service or authorized overhaul; field replacement of the EM35 actuator is documented in the 3103 manual
In hazardous (classified) areas, wiring must comply with applicable regional electrical codes
Woodward recommends overhaul based on operating hours or calendar age, whichever occurs first