The Duct Flow program is a handy tool for calculating the air flow parameters in ductwork. It gives the intermediate velocities, velocity pressures, static pressures and a running total of the static pressure for a ductwork path. The ductwork path can be the whole path or just a portion of the path. By comparing path portions the program locates the critical path in a multi-branch system. The ductwork path or duct route is assembled as a list of duct items on a spreadsheet like grid.