What type of pump always requires priming?

Centrifugal pumps are designed to move fluid by converting rotational kinetic energy from a motor to energy in the fluid flow. However, they rely on the fluid entering the impeller to generate the necessary flow. If there is air in the pump or piping system, it can prevent proper operation and lead to failure to create the required suction, thereby making it essential for centrifugal pumps to be primed.

Priming involves filling the pump and suction line with the liquid to remove any air. This is particularly important for centrifugal pumps because, without the liquid, they cannot create the necessary vacuum to draw in more fluid. Once the pump is primed with liquid, it can efficiently operate and maintain its function.

In contrast, diaphragm pumps, positive displacement pumps, and submersible pumps either do not require priming or can work effectively in a different manner where the fluid can be drawn in without the same necessity for being filled with liquid beforehand. Diaphragm pumps can operate in a variety of conditions, including dry, and positive displacement pumps are designed to move a set volume of fluid with every cycle, making them more forgiving of air in the system. Submersible pumps are immersed in the liquid they are pumping, so they do not encounter the air