Air Duct Cross, Rectangular, Diverging

This page calculates the local pressure loss of a rectangular cross (four-way distribution) fitting connected to an air duct system. The calculation is based on the principles of the ASHRAE Fundamentals Handbook – Chapter 34 and considers airflow distribution between the main duct and branches, duct dimensions, and air density. As a result, the additional pressure loss caused by the cross fitting and the corresponding velocity pressures are presented separately.