Ductile iron balance valve is a manual preset valve, which can adjust the flow rate and balance function. It has better equal percentage flow characteristics, can distribute flow reasonably, and effectively solve the problem of heating (air conditioning) system. The problem of uneven heat and temperature at room temperature. At the same time, the pressure drop and flow rate can be accurately adjusted, which can improve the liquid flow state in the pipe network system, achieve the liquid balance of the pipe network and save energy. At the same time, by installing the balancing valve, the total water volume of the system can be controlled within a reasonable