Friction Loss

Friction loss, abbreviated as FL, is how much loss of flow through a pipe is due to the viscosity, the measure of the internal friction/resistance to the flow of a liquid near the surface of the pipe.   

 

Friction loss formula
\(\large{ FL =  f \; \frac{ l }{ d } \; \frac{ v^2 }{ 2 \; g }  }\)
Symbol	English	Metric
\(\large{ FL }\) = friction loss	\(\large{ lbf }\)	\(\large{ N }\)
\(\large{ f }\) = friction factor	\(\large{ dimensionless }\)
\(\large{ d }\) = inside diameter of pipe	\(\large{ in }\)	\(\large{ mm }\)
\(\large{ l }\) = length of pipe	\(\large{ ft }\)	\(\large{ m }\)
\(\large{ g }\) = standard gravity	\(\large{\frac{ft}{sec^2}}\)	\(\large{\frac{m}{s^2}}\)
\(\large{ v }\) = velocity of fluid	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)

 

Friction loss formula
\(\large{ FL = C \; \left( \frac{ Q }{ 100 } \right)^2  \; \frac{ l }{ 100 }   }\)
Symbol	English	Metric
\(\large{ FL }\) = friction loss	\(\large{ lbf }\)	\(\large{ N }\)
\(\large{ Q }\) = flow rate	\(\large{\frac{ft^3}{sec}}\)	\(\large{\frac{m^3}{s}}\)
\(\large{ C }\) = friction loss coefficient	\(\large{ dimensionless }\)
\(\large{ l }\) = length of pipe	\(\large{ ft }\)	\(\large{ m }\)