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Barr's formula

Values for calculation

$ N_{Re} $
$ ε $ $ \mathrm{m} $
$ D $ $ \mathrm{m} $
$ L $ $ \mathrm{m} $

Calculation

Friction factor

$$f=\left\{-2\cdot\log_{10}{\left[\cfrac{ε}{3.7\cdot D}+\cfrac{4.518\cdot\log_{10}{\left(\cfrac{N_{Re}}{7}\right)}}{N_{Re}\cdot\left(1+\cfrac{N_{Re}^{0.52}}{29}\cdot\left(\cfrac{ε}{D}\right)^{0.7}\right)}\right]}\right\}^{-2}$$

Loss coefficient

$$ζ=f\cdot\cfrac{L}{D}$$