An air treatment apparatus has a momentum separator positioned in an air flow path. The momentum separator has an upper wall, a lower wall, a sidewall extending between the upper and lower walls and a momentum separator air inlet. The upper wall comprises an upper screen and an upper end wall is spaced from and faces the upper screen wherein an upper air flow chamber is positioned between the upper end wall and the upper screen.

A hand vacuum cleaner has a cyclone assembly positioned in the air flow path, the cyclone assembly comprising a cyclone chamber, the cyclone chamber having a front end, a rear end, a cyclone axis of rotation extending between the front and rear ends, a cyclone air inlet and a cyclone air outlet provided at the rear end of the cyclone chamber, wherein the rear end is rotationally moveable by a rotational mount between a closed position in which the cyclone is closed and an open position wherein a rear portion of the cyclone is open.

A hand vacuum cleaner has a cyclone assembly positioned in the air flow path, the cyclone assembly comprising a cyclone chamber, the cyclone chamber having a front end, a rear end, a cyclone axis of rotation extending between the front and rear ends, a cyclone air inlet and a cyclone air outlet provided at the rear end of the cyclone chamber, wherein the rear end is rotationally moveable by a rotational mount between a closed position in which the cyclone is closed and an open position wherein a rear portion of the cyclone is open.

A compact disc stack cyclone separator includes: a fluid inlet; a vortex generator which generates a forced vortex; a conical or cylindrical vortex generating chamber; a separation chamber which is a cavity formed by downstream open ends of stacked truncated cones; narrow gaps between the stacked truncated cones, a collecting channel for heavy phrase fluid from the gaps between the stacked truncated cones which installed about the outlets of the gaps at upstream open end of the stacked truncated cones to channel heavy phrase fluid to a storage chamber of heavy phrase fluid; and an outlet for heavy phrase fluid to flow out from the storage chamber of heavy phrase fluid, while the outlet of light phrase fluid is annexed to the downstream open end of the last stacked truncated cone which is the downstream open end of separation chamber.

A compact disc stack cyclone separator includes: a fluid inlet; a vortex generator which generates a forced vortex; a conical or cylindrical vortex generating chamber; a separation chamber which is a cavity formed by downstream open ends of stacked truncated cones; narrow gaps between the stacked truncated cones, a collecting channel for heavy phrase fluid from the gaps between the stacked truncated cones which installed about the outlets of the gaps at upstream open end of the stacked truncated cones to channel heavy phrase fluid to a storage chamber of heavy phrase fluid; and an outlet for heavy phrase fluid to flow out from the storage chamber of heavy phrase fluid, while the outlet of light phrase fluid is annexed to the downstream open end of the last stacked truncated cone which is the downstream open end of separation chamber.

A docking station for a robotic surface cleaning apparatus has a momentum separator. The momentum separator has a plurality of walls comprising an upper wall, a lower wall and a first sidewall, wherein the first sidewall extends between the upper and lower walls, and wherein the first sidewall comprises a side screen. A first end wall is spaced from and faces the side screen wherein an up flow chamber is positioned between the first end wall and the side screen.

A docking station for a robotic surface cleaning apparatus has a momentum separator. The momentum separator has a plurality of walls comprising an upper wall, a lower wall and a first sidewall, wherein the first sidewall extends between the upper and lower walls, and wherein the first sidewall comprises a side screen. A first end wall is spaced from and faces the side screen wherein an up flow chamber is positioned between the first end wall and the side screen.

A water treatment device including a first hydrocyclone and a biocidal fluid injector is described. The first hydrocyclone has an internal space, a water inlet for supplying water into the internal space, a base outlet for discharging at least a part of the water, and an apex outlet. The biocidal fluid injector is configured to inject a biocidal fluid into the internal space for eliminating organisms present in the water. The biocidal fluid injector is positioned such that a pressure within the injected biocidal fluid is lower than a head pressure of the first hydrocyclone.

A vacuum cleaner has two cyclonic cleaning stages. The air outlet of the first cyclonic cleaning stage is located at the air inlet end of the second cyclonic cleaning stage. The axially opposed end of the second cyclonic cleaning stage is openable.

A vacuum cleaner has two cyclonic cleaning stages. The air outlet of the first cyclonic cleaning stage is located at the air inlet end of the second cyclonic cleaning stage. The axially opposed end of the second cyclonic cleaning stage is openable.