Which pump captures a specific volume of fluid per revolution and displaces the pumping fluid mechanically?

The correct choice is based on the operation of a specific category of pumps known as positive-displacement pumps. These pumps work by capturing a discrete volume of fluid in a chamber during each cycle (or revolution) and then forcibly moving or displacing that volume into the discharge pipeline. This mechanism ensures that the flow rate is relatively constant and is not affected by the system pressure, making them ideal for applications requiring precise fluid management.

In contrast, centrifugal pumps rely on rotating impellers to impart velocity to the fluid, which is then transformed into pressure. They do not function by mechanically displacing a fixed volume of fluid; instead, they are designed to move larger volumes at lower pressures.

Rotary pumps include several types of mechanisms, including gear, screw, or other rotating elements, but they fall under the broader positive-displacement category and thus also share similar principles.

Rotary vane pumps specifically utilize vanes that slide in and out of a rotor to create chambers that trap and move fluid, highlighting a more specialized application of positive-displacement technology. While they can also be considered positive-displacement pumps, the term positive-displacement encompasses a wider variety of pump designs beyond just rotary configurations.

Therefore, the designation of positive-displacement pump is the most accurate answer