Which fire pump is not designed to be self-priming?

The centrifugal fire pump is not designed to be self-priming due to its operational principles. Centrifugal pumps rely on the movement of a rotating impeller to create a difference in pressure, which draws water into the pump from a source. However, for a centrifugal pump to function correctly, it must be filled with fluid prior to operation, as it does not create sufficient vacuum pressure to pull fluid from a lower level if it is dry. This means that the pump must be manually primed, usually by filling it with water before starting it.

In contrast, other types of pumps such as rotary vane, piston, and rotary gear pumps use different mechanisms that allow them to self-prime. These pumps can create the necessary pressure differential to draw in water without needing external assistance to initially fill the pump chamber. Thus, understanding these distinctions highlights why the centrifugal fire pump is classified differently regarding its priming capabilities.