ANALYSIS OF THE HAZEN-WILLIAMS HEAD LOSS EQUATION ASSOCIATED WITH THE HYDRAULIC FLOWS FOR SMALL DIAMETER PVC AND POLYETHYLENE PIPES

摘要

The purpose of this work was to fit the Hazen-Williams equation using from the Darcy-Weisbach equation, to the hydraulic flows, improving its accuracy. Another objective was to evaluate the variation of the C coefficient, with the diameter and flow velocity, showing the inaccuracy in this equation for small diameter PVC and polyethylene pipes when no adjustments are made. Mathematical transformations were used combining both Hazen-Williams and Darcy-Weisbach equations, and using multiple linear regression to the transition zone data, modeling an explicit equation for the friction coefficient of the Darcy-Weisbach equation (f) and substituting that equation in the mathematical transformations. Definition from literatures was used for the other flow types. Accurate and simple equations were obtained, making unnecessary the choice of the C coefficient and the calculation of the f friction coefficient, simplifying and increasing the accuracy in the hydraulic designs.