YK43X/F/Y pilot operated piston gas pressure reducing valve belongs to pilot operated piston pressure reducing valve. It is composed of two parts: main valve and pilot valve. The main valve is mainly composed of valve seat, main valve disc, piston, spring and other parts. The pilot valve is mainly composed of valve seat, valve disc, diaphragm, spring, adjusting spring and other parts. The outlet pressure is set by adjusting the spring pressure, the diaphragm is used to sense the outlet pressure change, and the overflow area of the main valve throttle part is adjusted by the pilot valve opening and closing drive piston, so as to realize the function of reducing pressure and stabilizing pressure. YK43X/F/Y pilot operated piston gas pressure reducing valve is mainly used in gas pipelines, such as air, nitrogen, oxygen, hydrogen, liquefied gas, natural gas and other gases.