A dirt separator for a vacuum cleaner that comprises an inlet (6, fig 4) through which fluid enters the dirt separator and an outlet (7, fig 4) through which fluid exits the dirt separator. The dirt separator further comprises a filter assembly (13, fig 4) located downstream of the inlet (6, fig 4) and upstream of the outlet (7, fig 4), an opening through which the filter assembly (13, fig 4) may be removed from the dirt separator, and a hatch (15, fig 4) moveable between an open position in which the opening is uncovered and a closed position in which the opening is partially covered. When the filter assembly (13, fig 4) is removed from the dirt separator and the hatch (15, fig 4) is in the closed position, a bleed 60 is created around at least part of the hatch (15, fig 4) through which fluid enters the dirt separator in preference to the inlet (6, fig 4). When the filter assembly (13, fig 4) is located in the dirt separator and the hatch (15, fig 4) is in the closed position, the filter assembly (13, fig 4) seals against the hatch (15, fig 4) to close the bleed 60.
