Frictional head loss relation between Hazen-Williams and Darcy-Weisbach equations for various water supply pipe materials

This research presents the analytical relationship between the frictional head loss obtained by two of the most common equations; Darcy-Weisbach and Hazen-Williams, considering plastic and metallic pipe materials as major categories. A wide range of hydraulic situations have been covered for water supply systems for buildings through five models for each pipe material category, based on water temperatures ranging from 20°C to 60°C, pipe diameters from 15 mm to50 mm and volume flow rates of 0.25 lps to 2 lps. The head loss values obtained by both equations were used to establish the correlation between them by using statistical techniques. The analyses show reliable results with combined correlation coefficient of 0.981 between both equations for plastic and metallic pipes, while the R2 value for the trend line of head loss values obtained by these equations was found to be 0.9978. This relationship should prove to be very useful for the water supply pipe manufacturers and designers for the mutual conversion of frictional head loss values obtained by these equations.