presents the influence of different helium flow fluxes on the oxygen permeation flux through BCFT membranes with different thicknesses at 900 °C. It was found that the oxygen permeation flux increased rapidly with increasing helium flow rates. Whereas for the membranes thicker than 1 mm the oxygen permeation flux comes to a saturation level for sweep gas (He) flow rates above 90 ml/min, for the thin BCFT membrane the oxygen permeation flux continues to increase with He sweep flow rates.