Hale 4DK Series - Manual (Page 10)

10 Manual p/n: 029-0020-79-0
4DK Series Pumps
The pump has a suction inlet on the front.
The incoming fluid is directed to the impeller
through the suction piping.
Impeller
A hard anodized aluminum impeller provides
velocity to the fluid. This part is mounted on a
shaft that is rotated by the gearbox. The fluid
enters the rotating impeller at the intake (or
eye), and is confined by the shrouds and the
impeller vanes to build pressure. The vanes
guide the fluid from the inlet to the discharge.
Vanes curve away from the direction of
rotation so the fluid moves toward the outer
edge. The shrouds form the sides of the
impeller and keep the fluid confined to cen-
trifugal acceleration.
Figure 2 (on page 8) traces a drop of fluid
from the intake of the impeller to the dis-
charge outlet. The impeller is mount-ed so
that the discharging tube is widest at the
pump outlet. The volute collects the
fluid.
A further increase in pressure and a
decrease in velocity take place in the
diffuser which is cast into the pump
body.
Clearance Rings
Clearance rings seal the impeller,
preventing pressurized fluid from
leaving the pump volute and returning
to the intake of the impeller. Centrifugal
pumps have clearance rings at the impeller
intake to prevent leakage. This is accom-
plished by limiting the radial clearance be-
tween the spinning impeller and the stationary
clearance ring.
A clearance ring usually has a radial clear-
ance of about 0.0075” (0.2mm) or a 0.015”
(0.4mm) diametral clearance. However, the
clearance increases over time as the pump is
operated.
Wear is due to foreign material found in most
fluids. Clearance rings are designed for
replacement as the clearance increases from
usage and wear.
If a pump is operated without fluid for ex-
tended periods or without discharging fluid, it
may overheat. This may damage the pump
and the drive mechanism. Fluid should be
circulated to prevent overheating.
Bearings
Bearings support and align the impeller shaft
for smooth operation.
Mechanical Seal
A mechanical seal is standard on 4DK series
pumps. As shown in Figure 3, a stationary
seat is in constant contact with a rotating
carbon seal ring face to prevent leakage.
The sealing boot is made of a rubber elas-
tomer that is specifically designed for high
temperature operations.
PUMP DRIVES
4DK Series pumps are operated from the truck
chassis drive shaft through a split-shaft gearbox.
Towards
Pump Head
Pump Shaft
Figure 3: Mechanical Seal Parts
O-Ring
Stationary
Seat
Carbon
Seal Ring
Diaphragm
Spring
Retainer
Impeller
Side