Laboratory tests were conducted to determine the head losses in wyes and manifolds of conventional type, both with and without an internal tie-rod at the theoretical centre of the wye. These wyes and manifolds, having 45°, 60° and 90° subtending angles of the wyes, were symmetrical about the longitudinal axis of the main pipe. The apparatus and method of testing used in the tests are described. The experiment spans a range of Reynold's numbers from 85,000 to 420,000 in the influent main pipe. The analysis of experimental data is based on the energy equation of Bernoulli for the one-dimensional condition. The results of the tests are given in both tabular and graphical form. It appears that the coefficient of the form loss (the ratio of the form loss of a wye or manifold to the velocity head in the main pipe) is a function of the proportional flow of water through the branches, the size of the tie-rod used and the subtending angle of the wye. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate