Friction factors for a 368 mm (14.5 in.) diameter round nonporousfabric air dispersion system (fabric duct and fabricdiffuser combination product) were measured per ASHRAEStandard 120 (2008). Two configurations were tested. In oneinstance an internal frame (to maintain a round cross sectionwhen no air pressure was in the system) was absent. For othertests a skeletal metal frame was inserted into the fabric tube tomaintain the tube shape in the absence of static air pressure.The resulting pressure loss data suggest that 368 mm (14.5 in.)diameter round fabric air dispersion systems lacking an internalsupport frame should be categorized as "MEDIUM SMOOTH"in the Duct Design chapter of the ASHRAE Handbook of Fundamentals.Round fabric air dispersion systems possessing a skeletalmetal internal support frame can be categorized as"MEDIUM ROUGH" in the Handbook.