"In normal conditions, common centrifugal pumps are unable to evacuate the air from an inlet line leading to a fluid level whose geodetic altitude is below that of the pump. Self-priming pumps have to be capable of evacuating air (see Venting) from the pump suction line without any external auxiliary devices. Centrifugal pumps with an internal suction stage such as water jet pumps or side channel pumps are also classified as self-priming pumps. Centrifugal pumps which are not designed with an internal or external self-priming stage can only start to pump the fluid after the pump has initially been primed with the fluid. In addition, a suction-side swing check valve or a vent valve must be fitted to prevent any siphon action and ensure that the fluid remains in the casing when the pump has been stopped. In self-priming centrifugal pumps with a separation chamber the fluid pumped and the entrained air bubbles are pumped into the separation chamber by the impeller action."
"SELF PRIMING PUMP - SP-BIOC It covers products for drainage and water supply applications as well as centrifugal sewage pumps, tubular casing and vertical immersion pumps, submerged propeller units, submersible borehole pumps, submersible motor pumps and a solid separation system."