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Pump selection

and purchasing

5.1 Pump selection factors

One of the earliest decisions in the traditional design of a system is the
selection of the Head and Capacity for which the pump should be
sized. As was discussed in Chapter 3, this usually results in the selection
of the pipe sizes to be used which, in turn, determines the friction losses
to be overcome. With the introduction of various computer software
programs, the selection of pump performance and system performance
is now being combined. By using these programs to effectively compare
piping costs (and all related fittings), pump costs and power costs for
various pipe sizes, the optimum combination can be determined.
Regardless of how the Head- Capacity conditions may be selected,
much more information is requircd to ensure an optimal selection of
pump style. For example, let's consider the liquid itself.
9 Is it corrosive?

9 Is it abrasive?
9 Are there solid particles and, if so, what size and percentage are
they?

9 Is it a viscous liquid and if so, what is the viscosity?
9 Does it tend to crystallize or otherwise solidify?
9 What is the vapor pressure?
9 Is it temperature sensitive?
If the liquid to be pumped is cold, clean potable water, most people are
sufficiently aware of the character of that liquid to understand that none
of the above factors will play a significant part in the pump selection
process.

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