U.S. Patent Specifications

Pressure cabin control arrangement comprising a cabin, means including a source of air under pressure connected to the cabin, means for controlling the flow of air from the source to the cabin in response to pressure changes therein to maintain the pressure in the cabin substantially constant during operation below a predetermined external pressure, and means consisting of a venturi having a constantly open and unobstructed throat connected to the cabin for normally discharging air from the cabin at a substantially constant rate when the pressure within the cabin is maintained constant and the external pressure varies below a critical limiting percentage of about 90 per cent of the pressure maintained constant in the cabin.