Example:
• Duty point: 100 m3/h – 30 m – pump efficiency 78 %
• Pump shaft power: 10.5 kW
• Electrical motor rating (including margin):
10.5 * 1.25 = 13 kW
• IEC motor power rating available: 15 kW
6.2 Coupling selection
Standard Pin-bush type flexible coupling is used to connect
top / head shaft to motor shaft. (Fig 16, Pg. No. 12)
Couplings can be selected with Cast Iron or Forged steel as
standard material. Select the size of the coupling in accordance
with the recommendation of the coupling manufacturer.
Strictly follow the coupling manufacturer’s instructions for the
fitting of the coupling between the pump and the motor. Use
torque or power/100 rpm rating to select suitable coupling in
suitable MOC.
Check if the rated coupling speed is more than pump speed.
Also check the motor shaft dia. for selected motor is less than
or equal to the max. Shaft dia. mentioned in the coupling
catalogue.
Additional service factor must be considered in coupling
selection for special applications. (Refer table on next page for
coupling details in CI MOC)
Example:
• Power: 1000 hp, Pump speed: 980 rpm,
Service Factor: 1
(Power/100 rpm) Rating = hp * 100 * SF / rpm
= 1000*100*1 / 100
= 102
Select coupling with hp /100 rpm rating more than 102
• For other types of couplings such Metaflex / Spacer-Membrane
type / Rigid threaded type kindly consult WILO Mather and
Platt.
• Care should be taken to consider and maintain gap between
motor and pump half side of the coupling.
6.3 Selection
of Mechanical seal (If applicable)
Mechanical seal should be selected in accordance to type of
fluid, contents handled, and temperature and pump head.
Suitable seal plan should be selected as per pump
manufacturer’s recommendations. Care should be taken to
check availability of potable water on site if external flushing
is required.
6.4 S e l e c t i o n of forced water lubrication system
Forced water lubrication system should be employed when
the pumping media is hazardous, dirty and contains solid as
well as abrasive contents. Pump manufacturer should be
consulted priorly with detailed water chemical analysis report
to decide on with the feasibility of system. Pump
manufacturer will provide a schematic for forced water
system along with quantity of water required for shaft tube
and thrust bearing cooling per pump. Time required for
starting booster pump prior to main pumps will also be
provided by pump manufacturer. (Refer Fig. 18 Pg. No. 12)
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