# Head Friction Loss in Fittings and Valves

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Head loss, abbreviated as $$h_f$$, is the pressure drop caused by fittings and valves.

## Head Friction Loss in Fittings and Valves formula

 $$\large{ h_f = K \; \frac{v^2}{2 \; g} }$$

### Where:

 Units English Metric $$\large{ h_f }$$ = head loss frictional resistance $$\large{ dimensionless }$$ $$\large{ g }$$ = gravitational constant $$\large{\frac{lbf-ft^2}{lbm^2}}$$ $$\large{\frac{N - m^2}{kg^2}}$$ $$\large{ K }$$ = loss coefficient for fittings and valves $$\large{ dimensionless }$$ $$\large{ v }$$ = velocity of flow $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$