Pressure Loss Coefficients of 6, 8 and 10-inch Steel Pipe Fittings

The scope of this study includes the testing of 6, 8 and 10-inch wrought steel fittings with flowing water to determine their head loss coefficient values. The fittings comprise long elbows, reducing and expansion elbows, Tees, reducing Tees, concentric reducers and expansions. Sixty fittings from seven manufacturers (four manufacturers per fitting) were tested at specified ranges of flow velocities to determine their head loss coefficients. In addition, an uncertainty analysis was conducted to determine the errors associated with the test set-up, the instrumentation, and the procedures used for these tests. The head loss coefficients of the fittings and their ranges are presented in this report as a function of upstream flow velocity and the Reynolds number. The results of the study show that the K-value of long elbows is smallest for larger pipe fittings and increases as the pipe fitting size decreases. For branching flows in Tees, the K-value of the straight leg is very similar to those in reducing Tees. However, for branching flows in reducing Tees, the K-value of the branching leg varies with size and the percent reduction in flow area. The K-values of reducers and expansions show a weak dependence on upstream velocity. They are dependent on both the fitting size, and the percent reduction and expansion of the flow area.