KSB MK, Installation & Operating Manual

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4 Description of the Pump (Set)
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MK
4.5 Configuration and function
MKA
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Fig. 3: MK, MKA
1 Thrust and radial bearing 2 Radial ball bearing
3 Shaft 4 Support column
5 Discharge pipe 6 Bearing bush
7 Volute casing 8 Motor
9 Cover plate 10 Shaft coupling
11 Vapour barrier 12 Overflow opening
13 Radial bearing 14 Impeller
15 Clearance gap
Design The vertical non-self-priming submerged pump in single-stage, single-entry design
features an axial fluid inlet and a radial fluid outlet.
At the drive end the rotor is axially and radially supported by a radial ball bearing
which is greased for life; at the impeller end it is radially supported by a product-
lubricated bearing bush. It is connected to the motor by a rigid coupling sleeve.
Various installation depths can be accommodated by up to three support column sets
and matching incremental lengths of the shaft assembly. The required radial bearings
are lubricated by the fluid handled. As an alternative, external lubrication can be
used. To protect the drive-end radial ball bearing the shaft is enclosed by a vapour
barrier below the thrust and radial bearing. For pump sets installed with a cover
plate (MKA) the discharge nozzle of the volute casing is connected to the plate via a
discharge pipe.
Function The uniformly rotating impeller of the submerged pump transfers mechanical energy
to the fluid passing through. The fluid enters the pump set vertically via the suction
nozzle and is accelerated outward by the rotating impeller. In the flow passage of
the volute casing the kinetic energy of the fluid handled is converted into pressure
energy. The fluid leaves the pump set via the discharge nozzle. The clearance gap
minimises the fluid flowing back from the volute casing into the suction nozzle. On
the rear side of the impeller, the hydraulic system extends up to the radial bearing
with bearing bush. The shaft passes through the radial bearing.
Sealing Apart from a vapour barrier protecting the fixed bearing the pump set is seal-less. A
small amount of leakage flows into the support column at the shaft passage and
then through the overflow opening back into the tank.