Friction Loss

on . Posted in Classical Mechanics

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 \(\large{ ft }\)  \(\large{ m }\)

 

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Tags: Pipe Sizing Equations Friction Equations