The bubbling jetting transition regimes from large orifice submerged in water were investigated for various orifice diameters A simple and fast way for identifying the regime transition was successfully developed using electrical capacitance tomography (ECT) In all the experiments deionised water was liquid phase and air was gas phase Orifice gas velocity (V-N) and orifice diameter (d(o)) were varied from 0 8 to 186 m/s and 4-21 mm, respectively It was found that the V-N,V-trans strongly depends on the orifice diameter In the small orifice diameter (d(o) < 10 mm), V-N,V-trans greatly decreases with the increase of orifice diameter However, in the large orifice diameter (d(o) > 10 mm), the effect of orifice diameter on the transition velocity is insignificant Finally, the data obtained by ECT compares with other works and the dimensionless orifice Reynolds number (Re-o similar to 11,000) is preferred to identify the bubbling jetting transition regimes