Hazen-Williams Friction Loss Equation

Hazen-Williams friction loss calculator for water flow in pipes

 Solve for: Discharge, Q (ft3/s): Discharge and Velocity Pipe Diameter (Q known) Pipe Diameter (V known) Energy (Head) Loss (Q known) Energy (Head) Loss (V known) Pipe Length (Q known) Pipe Length (V known) Hazen-Williams Coefficient (Q known) Hazen-Williams Coefficient (V known) Velocity, V (ft/s): Select units: Pipe Diameter, D (ft): Use feet and seconds units Use meters and seconds units Pipe Length, L (ft): © 2014 LMNO Engineering, Hazen-Williams C: Research, and Software, Ltd. Head Loss, hf (ft): http://www.LMNOeng.com Energy Slope, S (ft/ft):

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:
k=1.318 for English units (feet and seconds).  k=0.85 for SI units (meters and seconds)
C=Hazen-Williams Coefficient. D=Pipe inside diameter.

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.

LMNO Engineering, Research, and Software, Ltd.
7860 Angel Ridge Rd.   Athens, Ohio 45701  USA   Phone: (740) 707-2614
LMNO@LMNOeng.com    https://www.LMNOeng.com

To:

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)

Unit Conversions

Other information:

Register

Discussion and References for Closed Conduit Flow