Which device traps a fixed volume of fluid to produce a pulse of flow?

Which device traps a fixed volume of fluid to produce a pulse of flow?

• A. Positive displacement pump
• B. Centrifugal pump
• C. Piston pump
• D. Diaphragm valve

Answer: (A)

A device that traps a fixed amount of fluid per cycle creates pulsatile flow. In a positive displacement pump, a sealed chamber holds a precise volume of fluid, and when the boundary (such as a piston, plunger, or diaphragm) moves, that exact volume is displaced. Because each cycle moves the same discrete amount, the output appears as a pulse rather than a constant, smooth stream. Among the options, this behavior is the hallmark of a positive displacement pump. A piston pump is a member of this family and shares the same pulsatile characteristic, but the key concept is the fixed-volume displacement per cycle. In contrast, a centrifugal pump relies on imparting velocity to the fluid for flow and tends to produce a steadier stream under typical conditions, and a diaphragm valve is a control device rather than a pump that traps a fixed volume to generate pulses.

A device that traps a fixed amount of fluid per cycle creates pulsatile flow. In a positive displacement pump, a sealed chamber holds a precise volume of fluid, and when the boundary (such as a piston, plunger, or diaphragm) moves, that exact volume is displaced. Because each cycle moves the same discrete amount, the output appears as a pulse rather than a constant, smooth stream. Among the options, this behavior is the hallmark of a positive displacement pump. A piston pump is a member of this family and shares the same pulsatile characteristic, but the key concept is the fixed-volume displacement per cycle. In contrast, a centrifugal pump relies on imparting velocity to the fluid for flow and tends to produce a steadier stream under typical conditions, and a diaphragm valve is a control device rather than a pump that traps a fixed volume to generate pulses.