This paper is concerned with the relation between the permeability of single vertical partitions, placed at the front edge of single troughs in a horizontal wind tunnel, and particle entrainment from the troughs. The partitions consist of perforated plates having various sizes and numbers of holes, with a wire mesh being attached to the plate in some cases. Entrainment experiments were conducted using five kinds of particles whose mean diameters were in the range 99-510μm. The mean air velocity tested was in the range 9.8-14.8 m/s. It was found that without the wire mesh the particle entrainment was least likely to occur when the hole area ratio of the perforated plate was in the range 0.25-0.35 regardless of the trough length, air velocity and the kind of particles in the experimental range studied. The use of wire mesh on the perforated plate proved to be effective in reducing particle entrainment.