The database assumes clean, straight, fully developed flow at the inlet. Add 10–20% margin for field-installed ductwork with burrs, misalignments, or protruding gaskets.
The primary use of the DFDB is calculating the requirements for commercial air handling units (AHUs) and fans. An accurate TSP calculation ensures that fans are neither undersized (leading to starving airflows) nor oversized (leading to excessive energy consumption, noise, and equipment costs). Value Engineering and Optimization ashrae duct fitting database version. 6.00.05