# Fanning Friction Factor

by Maylis
Tags: factor, fanning, friction
 P: 146 Hello, I was wondering if when calculating the fanning friction factor, do english units need to be used? The equation for the head friction is h_f = 4f(L/D)V^2/2 where L is the length, D is the diameter of the pipe, and f is the fanning friction factor. This ends up having units of length squared/time squared, but I think it should be power/mass
 HW Helper Thanks P: 5,158 I don't know about your dimensional analysis. The Fanning friction factor is non-dimensional. http://en.wikipedia.org/wiki/Fanning_friction_factor BTW, your formula for head loss due to friction is incorrect. It should be: h_f = 4f(L/D)V^2/(2g)
 P: 146 Is the g included whether you use english units or not? I get confused when I need to divide by g or not these days since we keep going back and forth with english and SI units
HW Helper
Thanks
P: 5,158

## Fanning Friction Factor

Yes, the g is always there, even in SI or furlongs per fortnight units. Do a dimensional analysis and confirm.
 P: 146 You can see why I was confused, this is directly and repeatedly on the lecture slides Attached Thumbnails

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