Let’s twist again

Hoover has challenged Dyson’s Dual Cyclone vacuum cleaners with a technology originally developed to separate gas from crude oil.

A compact inline device known as Wellsep was miniaturised and developed by engineers at the British Hydraulics Research Group for use in Hoover’s system.

To separate fine particles from air, the system subjects the `unclean’ air to a series of smaller and smaller cyclones. The smaller the cyclone the higher the `g’ force, and higher `g’ forces are better at removing small particles. A first stage vortex in the dust container spins out more than 90% of the dirt. In the second stage, a high velocity vortex concentrates fine dirt into around 20% of the air flow which is then cleaned again using a third-stage miniature cyclone. At this point, transport air is reinjected into the second stage for a final `scrub’ before exiting, in theory, completely clean. It is the third stage and recycle which differentiates this design from Dyson’s dual cyclone system, although the principle is essentially the same. James Dyson declined to comment.