Davies et al. [Davies, C.E., Krouse, D. and Carroll, A., 2007, Onset of Bubbling in Fluidized Beds of Silica Sand Particles: Determination from Pressure Drop Fluctuations, AIChE Annual meeting, Salt lake City, Utah, USA, November] have recently postulated that the von Neumann ratio, T, may be useful in identifying both minimum fluidizing velocity and minimum bubbling velocity, where x is bed pressure drop sampled at a rate circa 50 Hz - 200 Hz. Plots of the inverse of T against superficial velocity exhibited significant change at velocities consistent with those where bed height first changed (onset of fluidization), the packed bed pressure drop underwent a transition from a monotonic linear function of superficial velocity to a steady value (onset of fluidization) and standard deviation of bed pressure drop rapidly increased (onset of bubbling). If T were indeed a valid and acceptable indicator of both minimum fluidizing velocity and minimum bubbling velocity, a single campaign of pressure measurements could, in principle, be used to identify both of these parameters. In this paper we extend earlier work and present experimental evidence from a broad range of conditions in support of this conjecture.