Pump affinity law check: Does delivery head vary inversely with impeller diameter at constant speed? Assume the same pump operating at a fixed rotational speed. State whether the given statement is correct. Choose the correct option.

Difficulty: Easy

Yes — head is inversely proportional to impeller diameter
No — at constant speed, head is proportional to the square of impeller diameter (H ∝ D²)
Head is independent of impeller diameter
True only for axial-flow pumps

Correct Answer: No — at constant speed, head is proportional to the square of impeller diameter (H ∝ D²)

Explanation:

Affinity laws (for geometrically similar operation)

Implication at constant N
H ∝ D², so increasing impeller diameter increases the developed head; it is not inversely proportional.

Final Answer
False — delivery head increases with the square of impeller diameter at fixed speed.

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