IES -Operation difficulties in centrifugal pumps (Common Question )

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This is common question asked in UPSC ESE regarding centrifugal pump in Assertion-Reason format. Have a look...

a)   Pump fails to pump the fluid.
Cause &  Remedial Measures
1) Improper priming due to leakage of foot valve or incomplete filling.
   Repair or replace the foot valve, prime completely.

2) Head more than design head 
Reduce the head or change the pump

3) Clogging of impeller, suction pipe or strainer 
Clean the suspected part

4) Suction lift may be excessive
Reduce the height of pump above the sump

5) Speed more than design speed
Connect another prime mover of higher speed

6) Direction of rotation of impeller is wrong
Change the direction.

B) Pump does not give the required capacity
a) Leakage of air through the suction pipeor through the gland packingStop the leakage
 b) Damage to some parts of the pump bywear & tear Replace the damaged parts
c) Clogging of impeller passagesClean the impeller

C) Pump has poor efficiency
a) Higher than design speed Reduce the speed
b) Low head & higher dischargeReduce the discharge
c) Impeller touching, the casing orimproper alignment of shaft Carryout the necessary repair.

D) Pump stops working
-Suction lift is high
-Air entry into Pipe



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