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Piping System Friction
48 The Basic Tools
Figure 3.1 Bernoulli diagram.
3.3.1 Pipe friction formulas
The amount of friction that is created by flow of water in piping has
been determined by a number of sources. Today, there are two princi-
pal formulas for determining pipe friction. These are the Darcy
Weisbach (Fanning) and the Williams and Hazen formulas:
Darcy Weisbach formula (Basis for Table 3.5)
L V 2
Hf f (3.3)
D 2 g
where Hf friction loss, ft of liquid
L pipe length, in ft
D average inside diameter, ft
f friction factor
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