RP-963 -- Laboratory Testing of Selected HVAC Duct Fittings to Determine Flow Resistance (Phase IV) ✓ Most Recent

Energy use and the environment in mechanically-ventilated buildings are strongly influenced by the performance of heating, ventilation and air-conditioning (HVAC) systems, which is in turn governed by accurate prediction of pressure loss. This report presents the results of an investigation of pressure loss and associated loss coefficient, kfactor, for selected HVAC duct fittings used with square, rectangular, oval and round cross section ducts. Various aspects of HVAC design have been investigated with the study of different hydraulic diameters, transition ratios and angles of reduction and expansion.

This paper reports of experimental results obtained under the instruction of a detailed study of flow resistance by the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers). The object of this investigation is to experimentally test selected duct fittings for flow resistance for a comparison with Computational Fluid Dynamics (CFD), and to test other duct fittings so that data can be used to update the ASHRAE HVAC Duct Fitting Database (1994). The duct fitting construction in this investigation complies with the SMACNA HVAC Duct Construction Standards (1995) and the experimental tests comply with the ASHRAE Standards 120P (1995).