Question

A pump must be designed to deliver m'is of water against ahead of 28 m. The specifed shaft speed is 22.5 ts. References eBook & Resources Section Break Dificulty: Medium 8. Required information 10.00 points Determine the specific speed of the pump. Round the final answer to the nearest whole number Hints References eBook & Resources Check my work 9. Required information 10.00 points The type of pump appropriate for the given job is central pump True False

Answer 1

Specific speed of pump is given by N_{​​​​​​s}​​​ = N x Q^{​​​​​​0.5} / H^​​0.75

Where N = shaft speed in revolution per minute

Q = flow rate in cubic meters per second

H = Head in meters.

Now , 22.5 rps = 22.5 x 60 = 1350 rpm

So , N_{​​​​​s} = 1350 x 6^0.5 / 28^0.75 = 271.669 ≈ 272

Centrifugal pumps have specific speed ranging from 500 to 10,000 , with radial flow pumps at 500-4000, mixed flow at 2000-8000 and axial flow pumps at 7000-20,000. Values of specific speed less than 500 are associated with positive displacement pumps.

So , statement in question number 9 is False.