Because AutoCAD MEP 2022 toolset duct systems connect intelligently, the software can size duct systems automatically. A duct run is any ductwork connected to one or more outlet devices that have a defined outlet flow. Outlet devices, such as air diffusers, are considered the ends of the duct system. Each duct segment in the run can pass on the flow values for all outlet devices that are downstream from it. These flow values are used to calculate sizes for each duct segment in the run. This section describes the various duct sizing methods and tools in AutoCAD MEP 2022 toolset.