Which device operation involves trapping air/water and compressing it for discharge?

• A. Rotary Vane Pump Operation
• B. Centrifugal Pump
• C. Positive Displacement Pump
• D. Diaphragm Pump

Answer: (A)

Trapping a fixed amount of fluid and then compressing it as it’s moved to discharge is the way positive-displacement devices work. A rotary vane pump does this by using vanes inside a housing to form sealed pockets of air or water. As the rotor turns, those pockets are carried from the intake to the discharge side; their volume decreases as they move toward discharge, which compresses the fluid and pushes it out through the discharge port. This pocket-based, volume-trapping action is what makes the rotary vane pump operation fit the description.

Centrifugal pumps don’t trap and compress a fixed volume—they accelerate fluid and rely on velocity and diffusion to move it. Diaphragm pumps also trap fluid in a chamber formed by a flexible membrane, but the trapping mechanism differs from the vane-pocket compression described. The vane-based trapping and compression best matches the stated operation.