Which type of pump is generally favored for highly viscous fluids?

Positive displacement pumps are specifically designed to handle highly viscous fluids, making them the preferred choice for such applications. These pumps work by trapping a fixed volume of fluid and then forcing it through the discharge pipe. This mechanism ensures that the pump can effectively move thicker fluids that would not flow readily through other types of pumps.

In contrast, centrifugal pumps rely on rotational energy to create flow and pressure, which can be less effective with viscous materials due to increased resistance and reduced flow rates. Submersible pumps are typically used in situations where the pump must be submerged in the fluid; while they can handle some viscous fluids, they are not as optimized for high viscosity as positive displacement pumps. Gear pumps, while also a type of positive displacement pump, may not be as versatile or effective for extremely high-viscosity applications compared to other positive displacement designs.

Overall, positive displacement pumps offer the necessary force and efficiency to move highly viscous fluids, making them the appropriate choice in applications where fluid viscosity presents a challenge.