What major advantage does a positive displacement pump have over a centrifugal pump?

A positive displacement pump is specifically designed to move a fixed volume of fluid with each cycle, regardless of the pressure it encounters. This design allows it to create higher pressures compared to centrifugal pumps, which rely on impeller speed and are limited by the physical characteristics of the fluid and pump design.

The major advantage of a positive displacement pump over a centrifugal pump lies in its ability to effectively move viscous fluids and even pump air or gas under certain conditions. This characteristic makes positive displacement pumps versatile and applicable in scenarios where gas might be present in the liquid, which centrifugal pumps struggle to handle due to their reliance on continuous fluid flow.

In terms of operational costs and design efficiency, while these are important considerations in pump selection, they do not distinctly set positive displacement pumps apart from centrifugal pumps in the same way that the ability to handle gases does. Therefore, the specific capability of a positive displacement pump to operate effectively even with air in the fluid stream is what highlights its key advantage.