Fluidized beds have been used in industrial scale for almost a century. This unit operation can be applied to several processes in order to promote intimate contact between the particulate and fluid phase. Monitoring the operational conditions is of interest, as it guarantees a specific fluidization regime and, consequently, high rates of heat and mass transfer. This work analyses the standard deviation of pressure drop time series. This time domain technique is widely applied for signal processing due to its simple and rapid calculation. The data used are the experimental pressure drop time series, with atmospheric air as the fluid phase and glass beads belonging to the B group of the Geldart classification. The profile of the average and standard deviation were plotted against the gas velocity normalized by the minimum fluidization velocity. This analysis allowed the identification of a fluidization regime change. The results were in agreement with those present in the literature.