Can a positive displacement pump pump air?

A positive displacement pump is essentially designed to transport fluids by trapping a fixed volume of the fluid (or in some cases, gas) and forcing it into the discharge pipe. This can be accomplished through various mechanisms, such as gears, diaphragms, or pistons.

The reason a positive displacement pump can pump air is due to its operational principle. When the pump cycles, it creates a vacuum that allows the surrounding air to be drawn in. The trapped volume of air is then pushed out during the pump's discharge stroke. This is in contrast to centrifugal pumps, which rely on the momentum of rotating impellers for the movement of fluids and generally do not perform efficiently with gases.

Given this functional capability, positive displacement pumps can indeed handle air, making them versatile for situations requiring the transfer of gases or liquids. Their ability to maintain a consistent flow rate regardless of downstream pressure makes them especially valuable in applications where precise control is necessary.