The invention relates to a coating powder sieving device, specifically for a powder paint coating installation, having a screen surface for sieving a coating powder. The screen surface is angular. An ultrasonic probe excites vibrations in the screen surface wherein the vibrations in the screen surface occur substantially in a direction perpendicular to the screen surface. A powder fluidization hopper incorporating the coating powder sieving device and a powder coating installation including plural powder fluidization hoppers are also disclosed.