The ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) Duct Fitting Database is a collection of pressure loss data for various duct fittings, such as elbows, tees, and transitions. The database provides a comprehensive source of information for calculating pressure losses in duct systems.

By following this guide, you'll be able to effectively use the ASHRAE Duct Fitting Database in Excel to calculate pressure losses in duct systems and improve the accuracy of your HVAC designs.