The biggest difference between full bore ball valves and reducing bore ball valves is that the full bore ball valve has a constant-width flow passage. Its size cannot be less than the value specified by the standard, which is roughly equivalent to the nominal diameter of the specification. The inlet of the reducing bore ball valve is wider than the diameter of the flow path and the actual diameter of the flow path is smaller. For example, the flow passage diameter of the DN50 reducing bore ball valve is about 38mm, which is roughly equivalent to the specifications of DN40.