## Head Loss

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Head loss is combined of two major components: friction
losses and minor losses. Friction losses are head losses due
to the friction that the walls of the pipe imposes on a
liquid. Friction losses are dependent on the viscosity of
the fluid and the turbulence of the flow. Head loss due to
friction (hf) can be calculated using the Darcy-Weisbach
equation:

The friction factor, f, can be determined if you know the
relative roughness of the pipe, E/d, and by solving for the
Reynolds number, Re, and using the Moody Chart, which can be
found in any fluid mechanics book. The Reynolds number can
be found using the following equation:

Minor losses are losses due to the change in flow patterns of
the liquid, i.e. bends, valves, sudden changes in pipe
diameter, etc. Minor losses are usually negligible compared
to friction losses in larger pipe systems. Minor losses,
hm, can be determined by the following equation:

The coefficient of minor head loss can also be determined
from tables in your fluids mechanics book. There are values
for every type of valve, elbows, tees, bends, and sudden
and gradual expansions and contractions.

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