Points out that Chapter 33, Pipe Sizing, of the 1993 ASHRAE Fundamentals Handbook gives k-factors for screwed pipe fittings and flange-welded pipe fittings. The reference for these tables is the Engineering Data Book, Hydraulics Institute (1979). Examines how the k-factors are used and where they came from based on a review of ASHVE Guides and other sources. Concludes by pointing to the need for ASHRAE to carry out research with which to compare commercial fittings and to establish updated k-factors.

KEYWORDS: year 1995, frictional resistance, pressure drop, pipes, fittings, history, calculating, factors