The Jenike-method is state of the art in silo design for trouble-free flow, even for cohesive bulk solids. However, for some bulk solids, especially very cohesive and moist bulk solids, even the correct application of the Jenike-method can lead to an over-design of the silo outlet. If a reliable estimation of the critical outlet dimension is possible the dimension as well as the machinery costs can be reduced. Model testing can help to reduce the over-design but reasonable test equipment and flexibility are only possible with silo centrifuge testing. Results, regarding the state of stress and the critical outlet dimensions, from experiments using a silo centrifuge with cohesive and moist bulk solids are presented. The influence of creeping effects on silo design is investigated using the silo centrifuge with moist gypsum.