Q4Basic Mechanical Engineering
Question
2 marks
Q.4. What is meant by priming in centrifugal pumps?
Answer
Priming is the mandatory preparatory process of completely filling the suction pipe and pump casing with liquid before starting.
Centrifugal pumps are not inherently self-priming. If the casing is filled with air instead of liquid, the rotating impeller simply churns the air. Because the density of air is approximately 800 times less than water, the pressure difference generated by the impeller is too weak to lift water up the suction pipe. Priming physically expels all trapped air, replacing it with the working fluid, allowing the impeller to immediately generate the required high-pressure centrifugal head.