Which pump type utilizes adjustable vanes for operation?

The rotary vane pump is distinguished by its use of adjustable vanes, which play a crucial role in its operation. These vanes are mounted on a rotor that turns within a cylindrical cavity. As the rotor turns, the vanes slide in and out of slots, maintaining contact with the walls of the cavity and creating varying volumes that facilitate fluid movement.

The adjustment of these vanes allows for changes in the pump's displacement and pressure characteristics, making rotary vane pumps versatile for different applications. The ability to adjust the vanes can help accommodate fluid viscosity changes and improves efficiency, especially under varying operational conditions.

In contrast, other pump types do not feature adjustable vanes. Piston pumps use reciprocating motion to displace fluid, and while they can adjust flow based on stroke length and speed, they do not have adjustable vanes that change during operation. Centrifugal pumps rely on rotational force generated by impellers to move fluid, without the use of vanes. Lastly, rotary gear pumps operate using interlocking gears to move fluid, lacking any adjustable vanes in their design.

Thus, the characteristic feature of adjustable vanes in a rotary vane pump makes it the correct answer.