Reciprocating pump discharge: Double-acting cylinder formula Given a double-acting reciprocating pump with stroke length L, piston area A, and speed N (rpm), neglecting rod area on the return side. Choose the correct expression for theoretical discharge.
Mechanical Engineering
Hydraulic Machines
Difficulty: Easy
Choose an option
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AQ = (A × L × N) / 60
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BQ = (2 × A × L × N) / 60
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CQ = (π × A × L × N) / 60
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DQ = (A × L × N) / (2 × 60)
Answer
Correct Answer: Q = (2 × A × L × N) / 60
Explanation
Given data
- Double-acting pump (delivery on both strokes), stroke length L, piston area A, speed N rpm.
Concept/ApproachFor each revolution, a single-acting pump delivers one stroke volume A·L. A double-acting pump delivers two stroke volumes per revolution (neglecting rod area).
Step-by-step calculationDischarge per revolution = 2 × (A·L).Revolutions per second = N / 60.Therefore, Q = (2 A L) × (N/60) = (2 A L N)/60.
Common pitfallsForgetting the factor of 2 for double-acting operation, or mixing rpm with rps.
Final AnswerQ = (2 × A × L × N) / 60