Single impeller centrifugal electric pumps to transfer and/or supply large amounts of liquid. These electric pumps are widely used in the nautical sector where they are generally used to transfer non-flammable liquids such as gas-oil or to deliver fresh water to all the plants where a large flow rate is needed (for ex. air-conditioning units). Automatic operation can be achieved by equipping the pump with small or middle-sized surge tanks. Installing a non-return valve at the suction inlet is recommended.