Which is a unique feature of positive displacement pumps?

Positive displacement pumps are characterized by their ability to move a consistent volume of fluid with each cycle, regardless of the system pressure. This operational principle is what sets them apart from other pump types. One unique feature of positive displacement pumps is that they come in various designs, including both piston and rotary types.

Piston-type pumps utilize a reciprocating motion to push the fluid, which allows for high pressure and efficiency. Rotary pumps, on the other hand, move fluid through the rotation of gears, lobes, or other mechanisms, offering distinct advantages in terms of flow consistency and maintenance. The existence of both configurations within the category of positive displacement pumps highlights their versatility and adaptability to different applications and needs.

While other options reference valid points about pump operation, they do not uniquely define positive displacement pumps. For instance, the ability to deliver water primarily in one direction is common to many pump types, not just positive displacement pumps. The claim about being unaffected by pressure changes pertains more broadly to how these pumps maintain flow rather than defining a unique characteristic. Likewise, while they perform favorably at lower flow rates, this is not exclusive to positive displacement pumps since many different types of pumps can be efficient at various flow rates.