Fluid mechanical processes have been widely used for many years in the most varied branches of industry, and the importance of their study is justified by diverse applications and versatility. Several methodologies to analyze pressure fluctuations from these processes have been proposed, and among them it is possible to highlight the probabilistic approach, with the focus on the adjustment of probability density functions (PDF). In the present work, time series derived from pressure variations along the bed are evaluated from probability density functions, that allow not only to study the bed dynamics but also to provide characteristic transition bands for each fluid dynamics region. In this way, the present work studies the pressure fluctuations in a gas/particle bed in the condition of minimum fluidization using as particulate phase glass microspheres A, B and D of Geldart´s classification and air as working fluid. After extensive analysis it was concluded that the best probability density function that fit the data was the logistic function.