SSC JE Mechanical Engineering 2018 Set 1 Paper

Equivalent pipe is defined as the pipe of uniform diameter having loss of head and discharge equal to the loss of head and discharge of a compound pipe consisting of several pipes of different lengths and diameters. The uniform diameter of the equivalent pipe is called equivalent size of the pipe.
$\frac{{\mathit{L}}_{\mathit{e}}}{{\mathit{D}}_{\mathit{e}}^5}=\frac{{\mathit{L}}_1}{{\mathit{D}}_1^5}+\frac{{\mathit{L}}_2}{{\mathit{D}}_2^5}+\frac{{\mathit{L}}_3}{{\mathit{D}}_3^5}+---$
This equation is also known as Dupuit’s Equation.