HazenWilliams Friction Loss Equation 
HazenWilliams friction loss calculator for water flow in pipes 

Units: ft=foot, m=meter, s=second. HazenWilliams Equation: V = k C (D/4)^{0.63} S^{0.54} where S = h_{f} / L and Q = V π D^{2} / 4 k is a unit conversion factor: HazenWilliams Coefficient (C) varies from approximately C=60 for 40year old cast iron pipe to C=150 for new plastic pipe. The higher the C, the smoother the pipe. Table of HazenWilliams Coefficients. The HazenWilliams method is valid for water flowing at ordinary temperatures of 40 to 75 ^{o}F (4 to 25 ^{o}C) through pressurized pipes. The HazenWilliams equation is typically used to analyze city water supply systems. For other liquids or gases, the DarcyWeisbach method should be used. Major loss (h_{f}) is the energy (or head) loss (expressed in length units  think of it as energy per unit weight of fluid) due to friction between the moving fluid and the pipe wall. It is also known as friction loss. The DarcyWeisbach method is generally considered more accurate than the HazenWilliams method. However, the HazenWilliams method is very popular, especially among civil engineers, since its friction coefficient (C) is not a function of velocity or pipe diameter. HazenWilliams is simpler than DarcyWeisbach for calculations where you are solving for flowrate (discharge), velocity, or diameter. More Discussion and References.
© 19982022 LMNO Engineering, Research, and
Software, Ltd. All rights reserved. 
To: LMNO Engineering home page (more calculations) Related calculations: Design of Circular Water Pipes Calculator (HazenWilliams) Circular Water Pipes with Pump Curve Calculator (HazenWilliams) Fire hydrant flow test analysis Table of HazenWilliams Coefficients (C)
