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Centrifugal pump discharge formula at inlet For a centrifugal pump, let D be the impeller diameter at inlet, b the impeller width at inlet, and V<sub>f</sub> the flow velocity at inlet. Write the discharge Q in terms of these quantities (neglecting slip). Choose the correct option.

Difficulty: Easy

Q = π D V_f
Q = π b V_f
Q = π D b V_f
Q = D b V_f

Correct Answer: Q = π D b V_f

Explanation:

Concept
Discharge = (flow area at inlet annulus) × (radial/flow velocity).

Calculation
Inlet annulus area A = π D b. Therefore, Q = A V_f = π D b V_f.

Common pitfalls
Forgetting the circumference factor π D and using only b V_f.

Final Answer
Q = π D b V_f

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