Practical Two‐Stage Pipe Expansions for Centrifugal Pumps

Abstract

Four two‐stage pipe expansions were designed, constructed, and tested to estimate their annual operating cost in irrigation service. The hydraulic performances of these fittings were compared with past two‐stage expansion research. The fittings were compared to other commonly used pipe expansions to determine their economic competitiveness. Measured head‐loss coefficients for the two‐stage pipe expansions averaged 0.32 and 0.28 for the 50–100 mm and 75–150 mm expansions, respectively. Loss coefficients for the 100–200 mm and 125–250 mm averaged 0.17 and 0.16, respectively. The smaller two fittings performed worse than past research on two‐stage expansions would predict. The two larger fittings (100–200 mm and 125–250 mm) worked substantially better than predicted. The two‐stage fittings presented in this paper are practical alternatives to other pipe expansions under the pumping conditions typically seen in irrigation service. The two‐stage pipe expansions designed with commonly available parts were more efficient than comparable abrupt and single‐stage pipe expansions, and cost about the same.