What type of valve activates an inlet air unloader in response to receiver pressure?

The type of valve that activates an inlet air unloader in response to receiver pressure is a spring-loaded pilot valve. This valve operates based on the principle of utilizing a spring to control the flow of air based on the pressure in the receiver. When the pressure in the receiver reaches a predetermined level, the force exerted by the compressed air overcomes the force of the spring, causing the valve to activate. This activation allows for the unloading of excess air pressure, effectively managing the system's pressure levels and ensuring efficient operation of air compressors or other related equipment.

In this function, the spring-loaded pilot valve is crucial as it provides a reliable mechanism for pressure control. Unlike solenoid valves that require electrical input to operate, the spring-loaded pilot valve operates mechanically based on pressure differentials, making it a suitable choice for applications where electrical components might not be ideal. Lever mechanisms while useful in manual operations do not provide the automatic pressure response needed for an unloader function, and springs alone do not fulfill the role of controlling air flow, thus necessitating the inclusion of a pilot valve in the system.