Flow regime transition between dilute pneumatic conveying and fast fluidization is identified for two Geldart A particles and four Geldart B particles in a novel gas-solid fluidization system configuration without exit restrictions. The results indicate that both saturation carrying capacity G(s)* and saturated solid fraction epsilon(s, ch) strongly depend on superficial gas velocity and particle properties. Based on data from this study and literature, improved correlations for estimating G(s)* and epsilon(s, ch) were developed. The correlations predictions agreed much better with experimental data than previously reported correlations. (C) 2020 Elsevier B.V. All rights reserved.