The ZZY series self-operated pressure regulating valve requires no external energy; it uses the energy of the controlled medium to regulate automatically. It saves energy, allows the pressure setpoint to be adjusted during operation, uses a quick-opening characteristic and provides responsive action, good sealing, stable medium pressure, high regulating accuracy and low leakage. It is widely used with gases, liquids and steam in petroleum, chemical, power, metallurgy, food, textile, machinery and building-service equipment for pressure reduction/stabilization downstream or relief/stabilization upstream. With a condenser, it can operate continuously on steam up to 300°C.