Positive displacement pumps move fluid by trapping a fixed amount of fluid and then forcing it through the pump's discharge. They are suitable for handling viscous fluids since they can operate with higher suction pressure. Centrifugal pumps, on the other hand, are better suited for lower-viscosity fluids and are more efficient at transferring larger volumes of fluid.
Positive displacement pumps such as diaphragm pumps and gear pumps are typically used in low flow rate applications, while centrifugal pumps are commonly used in situations with high flow rates.