# Hazen-Williams Head Loss due to Friction Equation

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

This head loss due to friction formula is used in Hazen-Williams equations.

## Hazen-Williams Head Loss due to Friction Equation formulas

 $$\large{ h_f = \frac { 4.73\; l_p \; \left( \frac {Q}{C} \right) ^{1.852} }{d^{4.87} } }$$ (US units) $$\large{ h_f = 4.73 \left( \frac {Q}{C} \right) ^{1.852} \frac{l_p}{d^{4.87}} }$$ (US units) $$\large{ h_f = 10.7 \left( \frac {Q}{C} \right) ^{1.852} \frac{l_p}{d^{4.87}} }$$ (SI units)

### Where:

 Units English Metric $$\large{ h_f }$$ = head loss due to friction $$\large{ft}$$ $$\large{m}$$ $$\large{ Q }$$ = flow rate $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$\large{ C }$$ = Hazen-Williams coefficient $$\large{dimensionless}$$ $$\large{ d }$$ = inside diameter of pipe $$\large{in}$$ $$\large{mm}$$ $$\large{ l_p }$$ = lenght of pipe $$\large{ft}$$ $$\large{m}$$