A vacuum cleaner or a docking station has momentum separator having first and second sidewalls which are porous. A first air flow chamber is located exterior to the momentum separator between a first end wall, which is spaced from and faces the first side screen, and the first side screen. A second air flow chamber is located exterior to the momentum separator between a second end wall, which is spaced from and faces the second side screen, and the second side screen. In operation, air exits the momentum separator through the first and second side screens and travels through the first and second air flow chambers to the air outlet of the first and second air flow chambers.