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PRESSURE REGULATOR AND RELIEF VALVE.- This valve (fig. 1-9) converts the uncontrolled bleed air to a regulated air pressure of approximately 18 psi and routes it to the three distributor valves and the pressure gage. The combination valve is basically separate regulator and relief valves with the two valve bodies brazed together. A sensing line allows air downstream of the valve to be ported to the diaphragm in the valve's regulating chamber. As pressure builds up downstream, the diaphram raises, compresses the regulating spring, and raises the inlet valve toward its seat. When the predetermined outlet pressure is reached, the inlet valve is fully seated, shutting off the flow of bleed air through the valve. When the downstream pressure drops below the regulator setting, it reduces the air pressure under
the diaphragm and the regulating spring forces the inlet valve off its seat, allowing inlet air to restore the system operating pressure. The relief valve section of the valve is held in the seated position by spring pressure until the air pressure in the outlet port exceeds a predetermined safe pressure. In the event that the regulator diaphragm ruptures or the regulating portion of the valve fails for any reason, the relief valve can function as a pressure regulator as well as a relief valve to temporarily protect the downstream deice system components from excessive pressure. EJECTOR.- The ejector unit consists of a pressure port, a venturi, an overboard port, and a suction port. As air pressure from the pressure manifold enters the inlet. pressure port, it creates
Figure 1-9.- Deice system pressure regulator and relief valve. the necessary suction at the suction port and in the main suction line to the distributor valves for deflating the deice boots.
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