In the present work, a novel cartridge type powder feeder is developed by applying 'subliminal fluidization', which is defined as partial aeration to the bed below minimum fluidization. but only for a limited region above the distributor, and by discharging solids together with the air through the tube located at the centre of the distributor. The distinct advantage of cartridge type feeder developed in this work lies in its simplicity of construction and operation giving quite an advantage for particulate material handling, transportation and metric feeding. Temporal solid efflux rates were measured for charcoal of mean sizes 220,290 and 430 pm,glass beads of 265,535 and 930 mu m and spherical activated alumina (Neo beads) of 145 and 595 mu m and density in the range of 1250 to 2500 kg/m(3). Temporal flow rates of solids indicated that the solids efflux was independent of time and amount of material inside the bed and was only determined by the air supply from the distributor plate. Solids efflux rate was found to decrease with increased particle size and internal friction and reduced fluidization air flow rate. Solids efflux was found to vary slightly with the change in air humidity. A dimensionless correlation for solids efflux was developed as a function of fluidization number and the internal friction angle. (C) 2008 Elsevier B.V. All rights reserved.