How does a positive displacement pump operate?

A positive displacement pump operates by continuously enclosing and moving a fixed volume of fluid with each cycle of the pump. This mechanism allows the pump to effectively deliver a consistent volume of fluid regardless of the system pressure, differentiating it from other types of pumps like centrifugal pumps.

In a positive displacement pump, the volume of the liquid that is moved is determined by the physical design of the pump (like gears, pistons, or diaphragms), and it does not rely on fluid dynamics or centrifugal force to achieve flow. Instead, as the pump's moving parts cycle, they trap a certain amount of fluid and then displace it out into the discharge line. This characteristic makes positive displacement pumps ideal for applications requiring precise flow rates and high viscosity fluids.

The other options describe principles that do not align with how positive displacement pumps function. Centrifugal force pertains to centrifugal pumps that rely on kinetic energy to move fluid. Creating suction is also more indicative of how some other pumping mechanisms might work, while relying on gravity is related to specific processes like siphoning or gravity feed systems, not to the operation of a positive displacement pump.