Training Manual on Energy Efficiency - APO Asian Productivity ...

<strong>Training</strong> <strong>Manual</strong> on Energy Efficiency for Small and Medium Enterprises
Friction head (sometimes called dynamic head loss) is the loss due to
friction on the liquid being moved, in pipes, valves, and equipment in the
system. Friction tables are universally available for various pipe fittings and
valves. These tables show friction loss per 100 feet (or meters) of a specific
pipe size at various flow rates. In the case of fittings, friction is stated as an
equivalent length of pipe of the same size. The friction losses are proportional
to the square of the flow rate. A closed loop circulating system, without a
surface open to atmospheric pressure, would exhibit only friction losses and
would have a system friction head loss vs. flow curve as shown in Figure 7-3.
Figure 7-3 Friction head
Most systems have a combination of static and friction head, and the
system curves for the two cases are shown in Figures 7-4 and 7-5. The ratio
of static to friction head over the operating range influences the benefits
achievable from variable speed drives.
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