pump capacity vshead/power

[subbaraao]

Can any one tell me the relation between pump capacity,head & power. We have a pump of capacity 125cumph head 50 meters motor 37kw&rpm 2900. If we reduce rpm to 1440 what would be the capacity,head&motor power required

 

[Artisi]

Q (flow) changes as the ratio of speed
Head changes as the square of the speed change
Power changes as the cube of the speed change


Q = N1/N2. Flow will be 62.5 cumph

Head = (N1 /N2)^2. Head will be 12.5 metres

Power = (N1 / N2)^3. Power will be 4.625Kw

 

[SNORGY]

At an apparent pump efficiency of 46%...

Regards,

SNORGY.