Pneumatic conveying, employing the dense phase plug flow regimen, is largely used to transport bulk solids. This process permits the conveying of large amounts of material in economical manner with less particle and pipe degradation compared to dilute phase conveying. By using an experimental system with special measurement devices and different materials of construction and transport, the friction between the material being transported and the pipe wall, the actual motion of the particles was determined, and the degree of fluidization were estimated. This information permits more accurate modeling of dense phase plug flow providing basic parameters to insert in existing and developing models. (C) 2003 Published by Elsevier B.V.