Flammability studies of air/cork dust mixtures were conducted in a near-spherical 22.71 explosibility test chamber, using 2500 J pyrotechnic ignitors. The suspension dust burned as air-dispersed dust clouds and the uniformity of the dispersion in the chamber was evaluated through optical dust probes. Tested particle dust had mass median diameters of 71.3 and 222.1 mum and the covered dust cloud concentration was up to 700-800 g/m(3). Measured explosion parameters included minimum explosion concentration, maximum explosion pressure and maximum rate of pressure rise. The effect of initial pressure on the explosion characteristics parameters was studied by varying the initial absolute pressure from 0.9 to 2.2 bar, and it was found that as initial pressure increases, there is a proportional increase of minimum explosion limit, maximum explosion pressure, and maximum rate of pressure rise. (C) 2003 Elsevier Ltd. All rights reserved.