HALE Silencer AP Series, Installation, Operation And Service Maintenance Manual

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Section 2: Introduction
Hale Products, Inc., May 2006, Rev-B
Introduction
❑
2 Introduction
2.1 PRINCIPLES OF OPERATION
Centrifugal Force
Hale pumps are centrifugal pumps that operate on the principle of centrifu-
gal force created by a rapidly spinning disk. (See Figure 2-1: “Centrifugal
Force - Rotating Disk.”)
As the disk rotates, it throws water from the center
toward the outer circumference of the disk. The
velocity at which the water travels directly relates to
the diameter of the disk and the speed of rotation.
When water is confined in a closed container, such
as the volute (pump body), the velocity of the water
is converted to pressure that rises to a level depen-
dent on the speed of rotation.
Three interrelated factors regulate the performance
of a centrifugal pump:
❑
SPEED (RPM) If the speed of rotation
increases with flow held constant, fluid pressure
increases.
❑ PRESSURE If pressure changes with speed held constant, the flow,
measured in gallons or liters per minute (GPM / LPM / LPS), changes
inversely; if pressure increases, flow decreases. Pressure is measured
in pounds per square inch (PSI) or BAR (MPa).
❑ FLOW If the pressure is held constant, the flow increases with an
increase in the speed of rotation. Flow is measured in the number of gal-
lons of fluid per minute (GPM / LPM / LPS) that a pump can deliver when
supplied from draft.
A centrifugal pump has the ability to fully utilize any positive suction inlet
pressure, thus reducing the amount of work done by the pump.
For example, if the required discharge pressure is 120 PSI (8.3 BAR / 0.8
MPa) and the inlet pressure is 45 PSI (3.1 BAR / 0.3 MPa), the pump must
only produce the difference in pressure or 75 PSI (5.2 BAR / 0.5 MPa).
Figure 2-1: Centrifugal
Force - Rotating Disk