Pressure Loss

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.

 

Pressure Loss formulas

\(\large{ \Delta P = \frac{f \; l  \;v^2}{2 \; g \; d}  }\)

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

Where:

Units	English	SI
\(\large{ \Delta P }\) = pressure loss	\(\large{\frac{lbf}{in^2}}\)	\(\large{Pa}\)
\(\large{ \bar {v}  }\) = average velocity	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)
\(\large{ \rho }\)   (Greek symbol rho) = density	\(\large{\frac{lbm}{ft^3}}\)	\(\large{\frac{kg}{m^3}}\)
\(\large{ f_f }\) = Fanning friction factor	\(\large{ dimensionless }\)
\(\large{ f }\) = friction factor	\(\large{ dimensionless }\)
\(\large{ g }\) = gravirational acceleration	\(\large{\frac{ft}{sec^2}}\)	\(\large{\frac{m}{s^2}}\)
\(\large{ d }\) = inside diameter of pipe	\(\large{ in }\)	\(\large{ mm }\)
\(\large{ l }\) = lenght of pipe	\(\large{ ft }\)	\(\large{ m }\)
\(\large{ v }\) = velocity of fluid	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)