A canister type of vacuum cleaner houses the suction motor and filtering system in a somewhat square or rectangular container. Variations of this type are the tank type vacuum cleaner which has a long tubular main body and the central vacuum which is mounted on a basement or garage wall. Typically incorporating a "clean-air" system, they are known for producing strong suction for use with the attachments. When a power nozzle is part of the system it is often referred to as a power team. A canister type vacuum cleaner usually contains wheels which allow it to be pulled after the user by its hose.
The suction motor design in a canister type creates significantly more actual suction (pressure difference) than the traditional upright motor design. This is important for effective cleaning with a hose and attachments due to the higher resistance to air flow present in the hose. The velocity of the air flow plus the amount of the carpet agitation determines how well a vacuum cleaner will pick up the dirt. To effectively clean carpeted floors, a power nozzle containing a motor driven revolving brush should be used to obtain adequate agitation of the carpet fibers. For more about suction motor and fan designs, see our articles on Suction Motor Design & Operation and Fan or Impeller Types & Performance.
While an upright specializes in cleaning carpets, a canister type vacuum cleaner specializes in cleaning with its attachments. On-board attachments on uprights are handy to clean a corner or your upholstered furniture but are somewhat limited in what they can do efficiently. A canister type usually has a longer hose, additional attachments for cleaning floors and more suction when using the attachments. They are easily pulled around by their hose, something uprights usually won't do without tipping over. Many canister types carry their attachments conveniently with them for fast switching from one to another. Power teams easily compete with uprights when it comes to effectively cleaning carpeted floors and are generally more versatile with the attachments.
The air enters the nozzle near the floor and travels through the wands and hose toward the paper filter bag, carrying the dirt with it. The bag retains most of the dirt and dust while allowing the air to pass through its filter media. The air then travels through a filter pad to be cleaned further before entering the high speed suction fan or fans. Since the air is quite clean, it is allowed to flow through the motor to cool it. After leaving the motor the air is often filtered by additional exhaust filters to remove even more fine particles and carbon from the motor brushes before it leaves the vacuum cleaner. Since the "clean-air" suction motor design creates more suction (pressure difference) than a traditional upright design, more filtering can be done without significantly effecting the air flow. "Clean-air" uprights and canisters can easily have filtration efficiencies which meet the HEPA specification when equipped with appropriate filters.
A canister type vacuum cleaner is very versatile, providing superior suction for use with the attachments. When it includes a motorized power nozzle or when teamed with a good upright it will clean all surfaces effectively. These combinations provide an excellent alternative to using an upright with on-board attachments.
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