Deice pressure regulating valve

is located in each engine pylon, and one is located in the forward upper left section of the ECS compartmen. The pressure regulating valve is normally closed, and is electrically controlled and pneumatically actuated. The pressure regulator valve has two functions; to regulate deice air pressure when energized and to shut off deice air when de-energized. The pressure regulator valve functions on differential pressure to maintain an outlet duct pressure of 26±2 psi. Acuation of the pressure regulator valve to the regulating function is accomplished by setting the deice switch on the ENVIRONMENTAL panel on the center console to WING EMP. The pressure regulator valve is normally closed because the valve sleeve is spring-loaded closed. Inlet air pressure (chamber C) is sensed by the control air pressure regulator, which, when the deice system is operating, maintains an output of constant reference pressure to control the opening side of the sleeve (chamber B). Chamber A is the closing side of the valve sleeve and is vented to the pressure regulating valve outlet pressure. Figure 1-12.—Deice pressure regulating valve. 1-15