Pressure Loss in Elbows and Duct Branches

The pressure loss in a duct branch is a function of at least six independent variables, and there is no complete set of data available for correlation. Equations [II] and [III] of this paper are derived on a theoretical and experimental basis. These equations correlate all available data with fair accuracy with the aid of four experimental curves (Figs. 2, 3, and 5). Furthermore, they permit prediction of probable pressure losses for ducts heretofore untested. Similar formulas can be derived for elbows, diffusers, contracting passages, and other configurations, e.g., Equation (1) presents losses for elbows.