Operators of bulk material silos frequently face various flow defects. These include defects in flow continuity, vaults, stick rings, and dead zones in the bulk material. The application of aeration systems in bulk material silos is an effective method used in order to eliminate the above defects. This paper presents a study of the effect of an aeration system on wall pressures sigma(w) of bulk material in a silo during a targeted bulk material aeration and relaxation process, and analyses the results in light of the calculation standards for designing bulk material silos, namely CSN 73 5570 a DIN 1055. (C) 2010 Elsevier B.V. All rights reserved.