Hazen-Williams Friction Loss Equation |
Hazen-Williams friction loss calculator for water flow in pipes |
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Units: ft=foot, m=meter, s=second. Hazen-Williams Equation: V = k C (D/4)0.63 S0.54 where S = hf / L and Q = V π D2 / 4 k is a unit conversion factor: Hazen-Williams Coefficient (C) varies from approximately C=60 for 40-year old cast iron pipe to C=150 for new plastic pipe. The higher the C, the smoother the pipe. Table of Hazen-Williams Coefficients. The Hazen-Williams method is valid for water flowing at ordinary temperatures of 40 to 75 oF (4 to 25 oC) through pressurized pipes. The Hazen-Williams equation is typically used to analyze city water supply systems. For other liquids or gases, the Darcy-Weisbach method should be used. Major loss (hf) 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 Darcy-Weisbach method is generally considered more accurate than the Hazen-Williams method. However, the Hazen-Williams method is very popular, especially among civil engineers, since its friction coefficient (C) is not a function of velocity or pipe diameter. Hazen-Williams is simpler than Darcy-Weisbach for calculations where you are solving for flowrate (discharge), velocity, or diameter. More Discussion and References.
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To: LMNO Engineering home page (more calculations) Related calculations: Design of Circular Water Pipes Calculator (Hazen-Williams) Circular Water Pipes with Pump Curve Calculator (Hazen-Williams) Fire hydrant flow test analysis Table of Hazen-Williams Coefficients (C)
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