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System

Hydraulics

3.1 Pump limitations

A centrifugal pump is designed and produced to supply a whole range
of head-capacity conditions as identified by it's performance curve. The
pump will operate on that curve if it is driven at the particular speed for
which the curve is drawn. However, the actual conditions on that curve
at which the pump will run, will be determined by the system in which
it operates. So, for all practical purposes, the system controls the pump
and will determine the conditions at which the pump will operate,
regardless of the Head and Capacity for which it was purchased.
This is a considerable advantage from the safety aspect of the System, in
that the Centrifugal Pump is not normally capable of over-pressurizing
the System. However, in order to understand how the Centrifugal
Pump operates in a System, it is first necessary to understand some
aspects of system hydraulics and some of the more rudimentary
considerations of system design.

3.2 Liquid flow in pipes

For those who may be unsure of the manner in which liquids actually
respond to flowing through pipes, the following basic guidelines are
offered.

3.2.1 Specific gravity
Specific Gravity (S.G.) is used frequently in the discussion of fluids. It is
the name given to the ratio of the density of a liquid to the density of
cold water (specifically at 60~ Therefore, when dealing with cold
water, its value of S.G. is 1.0.

31 m