How do pumps add energy to a fluid through volumetric displacement?

Positive displacement pumps add energy to a fluid by trapping a fixed volume of fluid and forcing it through the system, rather than by increasing the fluid's kinetic energy.12

This process occurs through a cycle of volume change within the pump's chamber:3

• Intake: As the internal volume of the pump chamber increases (such as when a piston moves outward or gears unmesh), a partial vacuum is created, drawing fluid into the chamber.3
• Displacement and Compression: As the chamber volume decreases (such as when a piston moves inward or gears mesh), the trapped fluid is compressed, which increases its pressure.3
• Discharge: This increase in pressure forces the fluid out through the outlet line.3

These pumps, which include reciprocating types like piston and diaphragm pumps, as well as rotary types like gear pumps and vane pumps, are typically used to move relatively low volumes of fluid at high pressure. Unlike kinetic pumps, which rely on a rotating impeller to impart velocity, positive displacement pumps rely on the mechanical reduction of space to pressurize the fluid.32