Pilot Valve
Apilot valveis a smallvalvethat controls a limited-flow control feed to a separate piloted valve. Typically, this valve controls a high pressure or high flow feed. Pilot valves are useful because they allow a small and easily operated feed to control a much higher pressure or higher flow feed, which would otherwise require a much larger force to operate; indeed, this is even useful when asolenoidis used to operate the valve.
Pilot valves are often used in critical applications (i.e., emergency and safety controls) and arehuman-operated. They can be set up as a push-to-activate ordead man's switch.