KOEFISIEN KEHILANGAN TEKANAN MINOR PADA BELOKAN 90°, PERBESARAN, DAN PENGECILAN PIPA: STUDI EKSPERIMENTAL PADA ALAT HI-1060

Abstract

Minor head losses at pipe fittings affect the design of piping systems, yet the loss coefficients (K) reported in the literature are generally obtained under test conditions that differ from laboratory apparatus. This study aims to determine experimental K values for seven fittings on the HI-1060 Closed Conduit Pipe Network apparatus, namely a 90° mitre, a standard 90° elbow, smooth bends with radii of 40, 90, and 140 mm, a sudden enlargement (13.6 to 26.2 mm), and a sudden contraction (26.2 to 13.6 mm). Discharge was measured volumetrically at two flow rates, and head losses were calculated from upstream and downstream piezometer readings using the energy equation with zero-flow correction. At the higher flow rate (Re ≈ 26,000), the K values of the 90° mitre (0.66), standard 90° elbow (0.62), and sudden enlargement (0.86) are of the same order of magnitude as the literature values. The K value of the smooth bends increased from 0.30 to 0.75 as the R/D ratio increased from 2.9 to 10.3. The lower flow rate data (Re ≈ 10,100) showed inconsistencies attributed to the uncertainty of volumetric discharge measurement with a small collecting volume. These preliminary results indicate the need for additional flow rates, replications, and straight-pipe friction correction to obtain reliable K values.