A cyclonic separating apparatus for a cleaning appliance includes a plurality of cyclonic separators arranged in series for separating particles from a dirt- and dust-laden airflow, at least two or three collectors for collecting separated dirt and dust, and a closure member movable between a closed position in which the closure member closes an end of each collector and an open position in which separated dirt and dust can be emptied from the collectors. The ends of the collectors are separated by dividing walls. A expandable seal is provided between the closure member and the dividing walls to seal when the closure member is in the closed position. The expandable seal is able to seal effectively even if the closure member is misaligned, incorrectly fitted or if dirt and dust is present between the surfaces to be sealed.