Question

Discharge of a centrifugal pump is-

• A. Inversely proportional to the square of speed of its impeller
• B. Directly proportional to the speed of its impeller
• C. Inversely proportional to the speed of its impeller
• D. Directly proportional to the square of speed of its impeller

Answer 1

Answer:

B. Directly proportional to the speed of its impeller

The discharge of a centrifugal pump is given by the equation = $P_i\times D\times B\times V_{f}$ where Q is the discharge, $V_{f}$ is the flow velocity, D is the diameter of the impeller and B is the width of the impeller. As B is proportional to D and $V_{f}$ proportional to DN, where N is the speed in rpm,

$Q \propto D ^ 3 \times N$ and $Q\propto N$ hence Q is directly proportional to N.