<Li> Cyclonic separation: A vacuum cleaner employing this method is also bagless . It causes intake air to be cycled or spun so fast that most of the dust is forced out of the air and falls into a collection bin . The operation is similar to that of a centrifuge . </Li> <Li> Water filtration: First seen commercially in the 1920s in the form of the Newcombe Separator (later to become the Rexair Rainbow), a water filtration vacuum cleaner uses a water bath as a filter . It forces the dirt - laden intake air to pass through water before it is exhausted, so that wet dust cannot become airborne . The water trap filtration and low speed may also allow the user to use the machine as a stand - alone air purifier and humidifier unit . The dirty water must be dumped out and the appliance must be cleaned after each use, to avoid growth of bacteria and mold, causing unpleasant odors . </Li> <Li> Ultra fine air filter: Also called HEPA filtered, this method is used as a secondary filter after the air has passed through the rest of the machine . It is meant to remove any remaining dust that could harm the operator . Some vacuum cleaners also use an activated charcoal filter to remove odors . </Li> <P> Ordinary vacuum cleaners should never be used to clean up asbestos fibers, even if fitted with a HEPA filter . Specially - designed machines are required to safely clean up asbestos . </P>

Parts of the vacuum cleaner and its function