A pump converts mechanical energy into pressure in a flowing liquid. A centrifugal pump does this by centrifugal action. Refer to Figure 2. A centrifugal pump has two major components: the internal impeller and the outer casing. The liquid enters the suction of the pump at A. It then flows to B and outward through the channels of the impeller marked C. As the liquid flows outward in the impeller, the impeller imparts a very high spinning or tangential velocity to the liquid. The liquid then enters the volute of the pump, area D. Here the velocity energy is converted to pressure.