Question

Discharge of centrifugal pump will be
A. inversely proportional to the diameter of its impeller
B. inversely proportional to the square of the diameter of the impeller
C. directly proportional to twice the diameter of the impeller
D. directly proportional to the diameter of the impeller

Answer 1

Hint: Centrifugal pumps are helpful in the transportation of the fluids by the conversion of rotational kinetic energy into the hydrodynamic energy of the flow of fluid. The rotational energy is generally produced from an engine or electric motor. The action of an impeller can enhance the velocity of the fluid and pressure and direct it towards the pump outlet. This all will help you in answering this question.

Complete answer:
The affinity laws are otherwise known as the Fan Laws or the Pump Laws. From this we can understand that the discharge of a centrifugal pump will be directly proportional to square of the diameter of its impeller. Head of a centrifugal pump will also be directly proportional to the square of the diameter of its impeller. And the power created by a centrifugal pump will be directly proportional to the fourth power of its impeller. From this we can say that the discharge of the centrifugal pump will be inversely proportional to the square of the diameter. Hence we can conclude that the option B is the correct one.

So, the correct answer is “Option B”.

Note:
The affinity law is used for pumps or fans which are helpful in hydraulics or hydronics in order to find out the relationship between variables included in the pump or fan performance. Some examples for these are such as head, volumetric flow rate, shaft speed and also the power.