The influence of the location of gas introduction on the gas dispersion performance of upward and downward pumping 45 degrees pitched blade disc impellers has been studied. Ring spargers of various diameters are used, at positions both below and above the impeller plane. The adequacy of the two phase dispersion and the aerated power consumption of each impeller is found to be strongly influenced by the location of the sparger. For the arrangements studied, the geometry that provides the best gas dispersion performance is found to vary for each turbine. One common feature, however, is that the sparger configurations that place the point of gas introduction away from the centre and into the discharge stream from the impeller, result in a reduced influence of the aeration rate on power consumption, and the susceptibility of the turbine to flooding, while still providing good gas dispersion. This observation has important implications for the design of equipment for gas-liquid-solid mixing.