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The Darcy-Weisbach equation is used to determine flow characteristics in closed conduit systems (pipes). It is probably more common than the Hazen-Williams equation due to it being able to solve for systems in both laminar AND turbulent flow.

$$ h_f = f \frac{L}{D} \frac{V^2}{2g} $$

• headloss \(h_f\) (ft)
• friction factor \(f\), length \(L\)
• length \(L\) (ft)
• diameter \(D\) (ft)
• velocity \(V\) $$\frac{ft}{s}\)
• gravity g \(32.2 \frac{ft}{s^2}\)

Friction Factor

The friction factor \(f$$ is either given or must be calculated using a Moody-Stanton diagram (available in both the AIO and CERM). Getting the friction factor from a Moody-Stanton chart requires the Reynolds Number \(Re\), and relative roughness \(\frac{\epsilon}{D}\). Click here to continue reading →