The behavior of multiple spouts above a perforated plate in a 400 mm x 15 mm two-dimensional bed of glass beads with mean diameters from 214 mum to 1095 mum was investigated. The operation of the perforated-plate distributor was taken into account while phase diagrams for the 2-D bed of glass beads were mapped. Two types of incoherent spouting were observed. The stability of multiple spouts was affected by bed height, superficial gas velocity, particle size and distributor design.