There are two kinds of regulators that both control downstream pressure and upstream pressure. They are: A self-operated type, consisting of a spring diaphragm and restricting valve. Pilot-operated type that uses a high-gain pilot system to position a valve mechanism and control the gas flow and pressure. A pilot-operated pressure regulator is a valve mechanism that is controlled by a pilot system to control pressure. This mechanism manipulates the valve's position by varying the loading pressure. This article describes pilot systems and discusses pilot systems, unloading systems, pressure-loaded regulators, self-operated regulators, and other aspects of the subject.