Molecular excitations in liquids, recognized at the levels of melting, boiling, and critical temperatures, are replicated directly with larger particulate masses as velocities leading to incipient fluidization, elutriation and loss of phase distinction. The latter, analogously termed particle critical velocities, is of greater significance in the design of fluid-particle systems than its counterpart in vapor-liquid operations. This paper suggests a generalized correlation of critical velocity data based on dimensionless incipient fluidization (melting point) and terminal velocity (boiling point) correlants proposed in 1957. This approach has a distinct parallel in molecular systems and the phenomenon now recognized as that encountered industrially in August of 1966 within an FCC regenerator operating at the Montreal East Refinery of The Shell Oil.