The more the flapper moves, the more air it permits through the
supply nozzle and the less air it permits out the vent. This causes
the pressure in the torque motor to increase as the current
increases. The opening chamber (chamber A) also feels this increase
in pressure, and the valve moves toward the open position as the
pressure in the opening chamber builds and overcomes the spring
pressure holding the valve closed.
As the signal from the controller changes, causing the valve to
close, the current flow in the torque motor decreases and the flapper
moves toward the supply nozzle and away from the vent nozzle. This
causes the pressure in the opening chamber to decrease and the valve
moves toward the closed position.
When the anti-ice servo valve senses a pressure change in the
condenser due to the forming of ice, air is sent to the remote
actuator pressure sensing connection on the anti-ice valve. The air
enters the opening chamber (chamber A), and the valve moves toward
the open position.
Anti-Ice Valve Location.