Pump performance of a small airlift system for transporting solid particles is investigated experimentally. Six types of uprisers locally containing S-shaped portions are used to investigate the effect of local bends on the flow characteristics. The internal diameter of the upriser is 18 mm and its total height 3200 mm. Alumina particles of 3 mm diameter are used as solid particles. The relation between the discharged liquid flux and the flux of injected air are obtained, varying injected gas flux, particle flux, type of upriser, and submergence ratio. In addition, the particle motion in the upriser is investigated in detail by means of photographic observations. The physics of the phenomena is discussed from a practical viewpoint. (c) 2005 Elsevier Ltd. All rights reserved.