Experiments were carried out to examine the influence of both the type and the pressure drop of distributor plates on the fluidization quality of an atmospheric fluidized bed. Three different distributor types were used, perforated Perspex, metallic mesh, and porous ceramic, with pressure drops ranging from 0.05 to 350kPa and superficial air velocities ranging from 0.1 to 2.3m/s. Three sizes of silica Ballotini beads, 355-425, 600-710, and 850-1000m, were used as bed material. The static bed height was set to 300mm and was divided into six horizontal 50mm high slices. For each slice, pressure drop values were recorded for U0/Umf ratios from 20 to 1. In order to produce a reference for the pressure drop evolution, a modification of the two-phase theory was introduced, taking into consideration the increase in the average global porosity as well as the change in the ratio of flow through the bubbles versus the flow through the dense phase. This allowed assessment of the influence of the different operating conditions and setups on the quality of fluidization, Q*.