Introduction

The SonicFlo™ valve controls the flow of gas fuel to the combustion system of an industrial or utility gas

turbine. The unique design yields a linear flow characteristic unaffected by discharge pressure up to a

pressure ratio (P2/P1) of at least 0.8. The design also integrates the valve and actuator into a compact

assembly. The key characteristics of this valve are a highly linear critical gas flow versus stroke

relationship at constant upstream pressure. The integral actuator is a single-acting spring-loaded design

for failsafe operation. The actuator includes an onboard hydraulic filter for last chance filtration of the

fluid to ensure reliability of the servo valve and actuator. The servo valve is electrically redundant with

triple coil design. Feedback for the actuator is provided by a dual coil, dual rod LVDT (linear variable

differential transformer) directly coupled to the hydraulic piston.

Near the null current, the four-landed valve isolates the control port from the hydraulic supply and drain,

balancing the piston pressure against the spring to maintain a constant position. The control system,

which regulates the amount of current delivered to the coils, modulates the current supplied to the coil to

obtain proper closed loop position of the valve.