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Electro-pneumatic main outflow valve
The electro-pneumatic main outflow valve is mounted on the rear pressure bulkhead of the pressurized area. The outflow valve controls cabin pressurization by actuating atmospheric chambers. A flexible diaphragm connected to the poppet valve separates each chamber. A spring in the control chamber determines a fail-safe closed position for the poppet.
The pressure in the control chamber is determined by a torque motor quadrant in response to output signals received from the CPC. The quadrant alternately opens two nozzles, one admits cabin pressure into the control chamber (moving the poppet toward the closed position) and the other nozzle connects the control chamber to the jet pump pressure line (reducing pressure inside the control chamber and inducing the poppet towards the open position). The function of the main outflow valve is, in response to signals from the CPC, to regulate the airflow exiting the cabin, so as to:
-maintain the programmed cabin altitude,
-limit the rate of climb and descent.
The electro-pneumatic main outflow valve control chamber includes:
-a cabin altitude limitation capsule,
-an overpressure limitation protection,

-the negative pressure relief valve to prevent negative differential pressure. The cabin altitude limitation capsule, which is fitted with an aneroid capsule, detects the absolute pressure in the cabin. When the set pressure is reached (cabin altitude 14,500 ± 500 ft), a valve linked to this capsule interconnects the control chamber to the cabin pressure, which tends to close the outflow valve and pressurize the cabin again. The overpressure limitation capsule receives the external static pressure and the cabin pressure. When the difference between the two pressures reaches the calibration value of 9.6 psi, the capsule opens a valve and connects the control chamber to the outside, hence opening the outflow valve and causing depressurization of the cabin.
　
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本文链接地址：DASSAULT FALCON 900EX EASY SYSTEMS SUMMARY Air Conditioning & Pressurization(11)