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System Hydraulics
I
Hs
Figure 3.2: Pressure in a flowing system
3.2.4 Changes in an existing system
Please note that the following relationships are offered for those who
wish to approximate the effect of changes in an existing system. For
accurate data, it is recommended that the Hydraulic Institutes' Friction
Loss tables are consulted, either in their Engineering Data Book, or as
shown in Chapter 14 of this book.
3.2.4.1 The effect of capacity change on friction
When the flow rate is changed without changing the pipe size (i.e. D 2 =
D1), the approximate change in Friction Loss can be estimated as
shown.
where Q = Flow Rate
Hf = Friction Loss
In other words, the Friction Loss will vary as the square of the Flow
Rate.
33 m
