-
a controller-housing assembly
-
a damper assembly
- a solenoid valve assembly - two pressure switches - a valve position microswitch.
When bleed-air pressure is applied upstream of the butterfly valve, and the solenoid valve is energized, the actuator and damper chambers pressurize. This opens the butterfly valve and lets bleed-air pass through the anti-ice control valve.
The anti-ice valve controls its outlet pressure to 1.55 bar (22.4808 psi) +/- 0.17 bar (2.4656 psi). When the bleed-air pressure is more than this, the controller-housing sensor diaphragm opens the sensor valve. This releases the pressure in the actuator chamber to atmosphere and closes the butterfly valve.
When the outlet pressure falls below the controlled value the damper spring closes the sensor valve. The actuator chamber then pressurizes again and opens the butterfly valve. The constant movement of the butterfly valve keeps the valve outlet pressure at the specified value.
The two pressure switches monitor the pressure downstream of the butterfly valve to sense a valve malfunction. If the pressure increases to 2.2 bar (31.9082 psi) the related switch gives a 'high pressure' signal. If the pressure decreases to 0.9 bar (13.0533 psi) the related switch gives a 'low pressure' signal.
The valve can be manually locked in the open or closed position by the lock pin. The pin is removed from the valve body and used to safety the valve indicator lever. When the lock pin is removed from its storage position, the actuator chamber is open to atmosphere, to prevent pneumatic operation of the valve.
The anti-ice valve has upstream and downstream ground-test connections. These let a functional test of the valve be done without bleed-air pressure in the ducts.
R **ON A/C 301-399,
R R R R R R R (2) Operation The wing anti-ice control valve has these primary components: - an actuator assembly - a butterfly valve - a solenoid valve - a pilot-valve assembly
R - two pressure switches
R - a valve position microswitch.
R
R When bleed-air pressure is applied upstream of the butterfly valve,
R and the solenoid valve is energized, the actuator middle chamber
R pressurizes. This opens the butterfly valve and lets bleed-air pass
R through the anti-ice control valve.
R
R The anti-ice valve controls its outlet pressure to 1.55 bar (22.4808
R psi) plus or minus 0.17 bar (2.4656 psi). When the bleed-air pressure
R is more than this, the pressure in the pilot-valve inner chamber
R opens the needle valve. This releases the pressure in the actuator
R middle chamber and closes the butterfly valve.
R
R When the outlet pressure falls below the controlled value the
R pilot-valve closes. The actuator middle chamber then pressurizes
R again and opens the butterfly valve. The constant movement of the
R butterfly valve keeps the valve outlet pressure at the specified
R value.
R
R The two pressure switches monitor the pressure downstream of the
R butterfly valve to sense a valve malfunction. If the pressure
R increases to 2.1 bar (30.4579 psi) the related switch gives a 'high
R pressure' signal. If the pressure decreases to 1.0 bar (14.5037 psi)
R the related switch gives a 'low pressure' signal.
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