# Hazen-Williams Flow Rate Equation

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

This flow rate formula is used in Hazen-Williams equations and the coefficient formula.  This formula only works for ambient temperatute and turbulent flow.

## Hazen-Williams flow Rate Equation formula

$$\large{ Q = 0.285 \; C\; d^{2.63} \; m^{0.54} }$$
Symbol English Metric
$$\large{ Q }$$ = flow rate $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$
$$\large{ C }$$ = Hazen-Williams coefficient   $$\large{ dimensionless }$$
$$\large{ m }$$ = hydraulic grade line slope $$\large{ ft }$$ $$\large{ m }$$
$$\large{ d }$$ = inside diameter of pipe $$\large{ in }$$ $$\large{ mm }$$