Y43H/Y pilot piston steam regulator 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, valve disc, piston, cylinder liner, spring and other parts. The pilot valve is mainly composed of valve seat, valve disc, diaphragm, spring, adjusting spring and other parts. Set the outlet pressure by adjusting the spring pressure, use the diaphragm to sense the outlet pressure change, and adjust the size of the overflow area of the main valve throttle part by driving the piston through the opening and closing of the pilot valve, so as to realize the function of pressure reduction and stabilization. This product is mainly used for steam pipelines, super decompression and pressure stabilization.