Do you know some knowledge points of Air Pilot Valves?

Air Pilot Valves are designed for simple and reliable air signaling within pneumatic systems. They offer a higher force than electrical solenoids or actuators for directional control applications as well as for use in remote applications where the power output from a pilot valve is much higher than the power produced by an electric solenoid.

Generally, pilot valves are either direct or indirectly controlled. A direct controlled directional control valve has a main control spool (main) and a pilot operator that is actuated by oil pressure.

The pilot operator moves the spool to open and close the valve. This spool is connected with the port P, B and A in the main valve by a spring chamber. The spool is moved back to its initial position when the solenoid coil is switched-off.

Pilot controlled safety relief valves are used to relieve overpressure from a system. They differ from the traditional pressure relief valve in that they seal by using the system pressure. They are typically fitted with an easing lever to allow the valve to be opened manually for safe checks and maintenance to prevent seizing or failure.

Usually, these valves are made from materials that will resist the effects of erosion and corrosion. For example, nozzles and discs can be made from austenitic stainless steel, or special alloys such as monel or hastelloy.

When the inlet pressure to the valve reaches its set point, the piston will pop out of its seat and disconnect from the main valve. This relieving action enables the main valve to open, allowing fluid to be discharged. As the inlet pressure is reduced to a lower value, the net closing force on the piston increases again to ensure that the valve remains shut-off.