Description
Woodward F8562-250
Technical Specifications
- Valve Type: High-pressure globe or ball valve.
- Actuator: Pneumatic or Hydraulic piston actuator.
- Positioner: Integrated electro-hydraulic or electro-pneumatic positioner.
- Flow Characteristic: Equal percentage or linear for precise turndown.
Functional Features
- Precise Metering: Maintains exact fuel flow despite upstream pressure fluctuations.
- Fast Closure: Meets safety shutdown time requirements (e.g., <1 second).
- Leakage Class: ANSI Class IV, V, or VI for tight shutoff.
- Position Feedback: High-resolution LVDT for closed-loop fuel control.
Application Scenarios
Gas turbine main fuel valves, compressor recycle valves, and boiler fuel control.
Performance Parameters
- Rangeability: High turndown ratio (e.g., 100:1).
- Hysteresis: <0.5% of span.
Material Composition
Stainless steel trim for corrosion resistance. Hardened seat and plug for erosion resistance from gas flow. Aluminum or ductile iron actuator housing.
Structural Characteristics
Top-entry valve body for easy maintenance. Side-mounted or top-mounted actuator. External positioner with local pressure gauges.
Working Principle
The positioner receives a 4-20mA signal from the turbine controller. It modulates pilot air/oil to the actuator piston, moving the valve plug to match the commanded position.
Installation Requirements
Install in the correct flow direction (arrow on body). Provide upstream and downstream isolation valves and a bypass for maintenance. Support piping to prevent stress on the valve body.
Usage Precautions
- Perform a leak test before introducing fuel.
- Cycle the valve regularly to prevent seizing.
- Monitor actuator air/oil supply pressure; low supply causes sluggish response.
