Head Losses in Wyes and Manifolds

by Eugen Ruus, (M.ASCE), Assoc. Prof. of Civ. Engrg.; Univ. of British Columbia, Vancouver, B.C., Canada,

Serial Information: Journal of the Hydraulics Division, 1970, Vol. 96, Issue 3, Pg. 593-608

Document Type: Journal Paper


Head loss coefficients are determined experimentally for symmetrical and unsymmetrical flow through nine symmetrical conical and spherical wyes and manifolds. The diameters of the main and branch pipes are 5-1/4 in. and 3-3/4 in. The angle of bifurcation varies from 45° to 90°. The conical wyes and manifolds are tested with and without tierods of 3/16, 3/8, 9/16 and 3/4 inc. diameter, placed in turn at the center of the wye. The diameters of the spheres of spherical wyes are 5.85 in. and 7.5 in. The head loss depends on the angle of bifurcation, the diameter of the tierod or the diameter of the sphere, and the ratio between discharges in the branch and main pipes. For symmetrical flow conditions the head losses caused by wyes or manifolds with an angle of bifurcation not over 60° are less than 10% of the velocity head in the main pipe. Tierods largely increase head losses and should be avoided.

Subject Headings: Head loss (fluid mechanics) | Symmetry | Bifurcations | Pipe sizes | Spheres | High-rise buildings | Pipe flow | Fluid velocity

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