A self priming pump is like any other centrifugal pump, but it is designed with an external casing that “floods” the inner pump or volute. The casing is filled with liquid [usually the same as the liquid to be pumped] and the pump is ready to go. When the impeller rotates in the casing, a low pressure area is formed at the eye of the impeller. Because the pressure is lower than atmosphere, water is pushed up the suction pipe by atmospheric pressure, forcing all the air in the suction line into the pump. The self priming pump mixes the air with the recirculating water in the casing. The air separates from the liquid and is discharged from the casing. When all the air in the suction line has been displaced, the pump is dynamic and delivers flow like any other centrifugal pump. Self priming centrifugal pumps can be applied to any application that standard centrifugal pumps are applied, within their hydraulic limitations. Applications from water, fuels, effluent or “grey water”, right through to raw sewage, industrial wastewater and sewage sludge can be effectively handled by self priming centrifugal pumps. Provided they are within their hydraulic limits, and they are manufactured with the right features for their intended duty, self priming pumps can deliver the safest and most cost effective of pump solutions.