# Hagen–Poiseuille Equation

Hagen–Poiseuille equation, also called Hagen–Poiseuille Law, Poiseuille equation, or Poiseuille law, gives the pressure loss in a fluid flowing through a long cylindrical pipe.

## Hagen–Poiseuille Equation formula |
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\(\large{ \Delta p = \frac { 8 \; \mu \; l \; Q }{ \pi \; r^4 } }\) | ||

Symbol |
English |
Metric |

\(\large{ \Delta p }\) = pressure loss | \(\large{\frac{lbf}{in^2}}\) | \(\large{Pa}\) |

\(\large{ \mu }\) (Greek symbol mu) = dynamic viscosity | \(\large{\frac{lbf-sec}{ft^2}}\) | \(\large{Pa-s}\) |

\(\large{ l }\) = length of pipe | \(\large{ft}\) | \(\large{m}\) |

\(\large{ \pi }\) = Pi | \(\large{3.141 592 653 ...}\) | |

\(\large{ r }\) = pipe inside diameter | \(\large{in}\) | \(\large{mm}\) |

\(\large{ Q }\) = volumetric flow rate | \(\large{\frac{ft^3}{sec}}\) | \(\large{\frac{m^3}{s}}\) |