Hale 4DK Series - Manual (Page 8)

8 Manual p/n: 029-0020-79-0
4DK Series Pumps
If pressure changes with speed held
constant, the flow, measured in gallons
per minute (GPM) or liters per minute
(LPM), changes inversely; that is, if
pressure increases, flow decreases.
❑ FLOW Flow is usually measured in the
number of gallons of fluid per minute
(GPM or LPM) that a pump can deliver
when supplied from draft. If the pressure
is held constant, the flow increases with
an increase in the speed of rotation.
A centrifugal pump is preferred due to its
ability to fully utilize any positive suction inlet
pressure, reducing the amount of work done
by the pump. For example, if the required
discharge pressure is 120 PSI (8.3 BAR), and
the inlet pressure is 45 PSI (3.1 BAR), the
pump must only produce the difference in
pressure or 75 PSI (5.2 BAR). This contrib-
utes to low engine and pump speeds with
reduced maintenance. Decreased mainte-
nance is aided by the fact a centrifugal pump
has few moving parts; such as the impeller,
shaft and seal.
Note: 4DK Series pumps are single stage
pumps, meaning there is a single impeller on
a common shaft.
As the impeller rotates the fluid moving
outward in the impeller creates a vacuum in
the suction eye allowing the pump to lift the
fluid into the volute (or body).
As fluid is evacuated from the suction pas-
sage atmospheric pressure pushes the fluid
through the suction passage.
Generally, the pump consists of the following
major components:
❑ Pump body
❑ Impeller and Shaft Components
❑ Gearbox
Self-Priming
The 4DK pumps can only self-prime if the
pump body is full of fluid. A recirculation
chamber and passage keeps the impeller eye
wet. This allows fluid to circulate inside the
pump providing the self-priming action.
CAUTION !
THE PUMP CANNOT SELF-PRIME AND WILL BE
DAMAGED IF RUN DRY FOR EXTENDED PERIODS
OF TIME.
Pump Operation
To develop the required volume and pressure,
the Hale 4DK series pump utilizes an impeller
with a single suction channel where fluid enters.
INTAKE
DISCHARGE
CUT WATER
EYE
VANES
DIFFUSER
Figure 2: Impeller Operation