Self-priming centrifugal pumps use suction lift to draw liquids from a source located below the pump's inlet. Before first use, these pumps must be primed to ensure a proper seal. The pump's head and flow performance increases as the HP rating increases. Different housing materials can handle fluids for various applications. Cast iron is more cost-effective but less corrosion-resistant than stainless steel, bronze, and aluminum. Aluminum resists corrosion better than cast iron and is lightweight. Bronze is corrosion-resistant and can handle potable water if NSF-certified. Stainless steel resists corrosion better than other materials and handles a wider range of liquids, including potable water if NSF-certified.