A model centrifugal pump with a constant speed motor has the following characteristics: Impeller diameter = 10 in. Speed = 1,800 rpm When pumping water at the rate of 7 ft 3 /sec, against a head of 10...

A model centrifugal pump with a constant speed motor has the following characteristics:

Impeller diameter = 10 in.

Speed = 1,800 rpm

When pumping water at the rate of 7 ft³/sec, against a head of 10 ft, 250 hp is required. It is desired to construct a larger, geometrically similar pump to pump water against a head of 160 feet that has:

Impeller diameter = 20 in.

Speed = 3,600 rpm

a) Find the flow rate at which this new unit should be operated if the efficiency is to be the same as that for the model pump.

b) What is the horsepower required when the new pump is operating under these conditions?