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.

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