Closed Conduit Hydraulics - Hazen Williams Equation

Hazen-Williams can be used to determine the flow characteristics in closed conduits (pipe systems).

For Velocity

S = slope, in decimal form. This is equivalent to

R = hydraulic radius,

C = Roughness Coefficient, get this from a table (available in both the AIO and CERM)

For Head Loss

To derive these  has been substituted for S.

The Hazen-Williams equation is similar to the Darcy-Weisbach equation, but it is only used for turbulent flow.

When to use Hazen-Williams

1. You are only given C
2. You prefer it and are sure the flow is turbulent (Reynolds number (Re) > 4000)
3. You are directly told to (from the examples it looks like several problem prompts do this)

When to NOT use Hazen-Williams

1. The flow is NOT turbulent (Re < 2100)
2. You are given . If you are given a friction factor use Darcy-Weisbach