# Pressure Loss

Written by Matt Milbury on . Posted in Pump

Pressure loss, abbreviated as $$\Delta P$$, also called pressure drop, is the difference in pressure between two points, usually caused by friction resistance in the pipe, but moisture can also affect it.

## Formulas that use Pressure Loss

 $$\large{ \Delta P = \frac{f \; l \;v^2}{2 \; g \; d} }$$ $$\large{ \Delta P = \frac{f \; l \;v^2}{2 \; g \; d} }$$ $$\large{ \Delta P = 2 \; f_f \left( \frac{ l }{ d } \right) \left( \rho \; \bar {v}^2 \right) }$$

### Where:

$$\large{ \Delta P }$$ = pressure loss

$$\large{ \bar {v} }$$ = average velocity

$$\large{ \rho }$$   (Greek symbol rho) = density

$$\large{ f_f }$$ = Fanning friction factor

$$\large{ f }$$ = friction factor

$$\large{ g }$$ = gravirational acceleration

$$\large{ d }$$ = inside diameter of pipe

$$\large{ l }$$ = lenght of pipe

$$\large{ v }$$ = velocity of fluid