Invention

Part 14 - Vacuum Cleaners

The vacuum cleaner evolved from the carpet sweeper, in 1860, when Daniel Hess of Iowa invented a vacuum cleaner with a manually operated rotating brush and a bellows to create suction. In 1898 John S. Thurman of Missouri patented a "pneumatic carpet renovator" powered by an internal combustion engine. It was mounted on a horse-drawn wagon and used for a door to door cleaning service.

James Murray Spangler was an asthmatic who, suspecting that sweeping dusty carpets in the Canton, Ohio, store where he worked was causing his cough, developed an electric carpet sweeper. It used suction from an electric fan to blow dust into a pillow case while a rotating brush loosened debris. It was the first commercially successful portable 'Electric Suction Sweeper'.   William Hoover bought Spangler's patent in 1908 and sold the first vacuum cleaner for $60 but sales did not take off until he offered customers a ten-day, free home trial.

In 1910, The Danish, Fisker and Nielsen company developed a vacuum cleaner weighing just 17.5 kg (39 lb) and by 1954 the company had sold 1 million units.

Cleveland's P.A. Geier Company patented on a cyclonic vacuum cleaner in 1928. This used centrifugal force to separate dust and particles from the air flowing through a cylindrical collection vessel. Upright vacuum cleaners typically have a fan and filter mounted on the handle and a rotating brush or beater bar to loosen dirt through by sweeping and vibration. One design has the fan behind the nozzle so the dirty air is blown into the filter bag. The other common design has the fan behind the bag so air is sucked through bag. Typically upright vacuum cleaners use a drive-belt powered by the suction motor to rotate the brush-roll but some designs use a separate motor to drive the brush roll. 

Canister models have the motor and dust collector in a separate unit, usually mounted on wheels, which is connected to the vacuum head by a flexible hose making it easier to vacuum stairs and vertical surfaces and to reach under furniture.

Drum or shop vac models are essentially heavy-duty industrial versions of canister vacuum cleaners. The fan and dust collector is mounted on a large vertically positioned drum that can be stationary or on wheels. Smaller, electrically powered versions are used in garages or small workshops. Larger stationary models, which can store over 200 litres (44 imp gal; 53 US gal), are often hooked up to a compressed air supply that uses the venturi effect to produce a partial vacuum.

Wet or wet/dry vacuum cleaners are a specialized form of the cylinder/drum models used to clean up liquid spills. They are typically designed to be used both indoors and outdoors and to accommodate both wet and dry debris; some are also equipped with a detachable blower for clearing a clogged hose or to blow dust or leaves for easier collection.

Backpack vacuum cleaners are small canister vacuums strapped onto the user's back allowing rapidly coverage of a large area. Lightweight hand-held vacuum cleaners, either powered from rechargeable batteries or mains power, are also popular for cleaning up smaller spills.In the late 1990s several companies developed robotic vacuum cleaners, a form of carpet sweeper usually equipped with limited suction power. These machines move autonomously while collecting surface dust and debris into a dustbin. They can usually navigate around furniture and come back to a docking station to charge their batteries.

In December 2009, Neato Robotics introduced a vacuum cleaner with a rotating laser-based range-finder (a lidar) to scan and map its surrounding methodically. It will note temporarily inaccessible areas and return later. It also has one of the more powerful fans on robotic vacuum cleaners, moving 35 cubic feet/min (1 m3/min) of air.

In 1979, James Dyson adapted a design from industrial saw mills and developed a portable unit with cyclonic separation. It first sold in Japan in the 1980s for about US$1800 and, in 1993, in the Britain for £200, twice the price of a conventional unit. Unexpectedly, the design became the most popular cleaner in the Britain.

In cyclonic cleaners high speed air and dust are sucked into a collection vessel at a direction tangential to the vessel wall, creating a fast-spinning vortex. The dust particles and other debris are flung to the outside of the vessel by centrifugal force and fall to the bottom of the vessel. The clean air is expelled from the top centre of the vortex and passes through a series of successively finer filters. These must be cleaned or replaced regularly to maintain efficiency. In contrast to filter bag systems, which lose suction as the filter become clogged, a cyclonic filtration system loses suction power only when the collection vessel is almost full.

Following Dyson's success, many other companies introduced cyclone models and the cheapest models are now priced similarly to filter bag cleaners.

A central vacuum typically provides greater suction than typical portable vacuum cleaners because a more powerful motor and larger fan can be used. Also, there is less noise in the room being cleaned, air is not exhausted into a living space and may be exhausted out side the building. In a central vacuum cleaner, the motor, fan and dirt collector unit are located in a central location in a building, and connected by pipes to vacuum inlets installed throughout the building. Only the hose and cleaning head need be carried from room to room, and the hose is typically long enough (8 m (25 ft)) to permit a large range of movement without changing vacuum inlets.

The dirt bag or collection bin in a central vacuum system is typically large enough that it does not need to be emptied frequently. The central unit is turned on by a switch on the handle of the hose or powered up when the hose is plugged into the wall inlet.

During World War II, the British Army Chemical Corps duplicated a German gas mask filter, that captured chemical smoke, and developed a combination fan and air purifier unit using deeply-pleated cellulose-asbestos paper. This led to the developing HEPA (high-efficiency particulate air) filters to collect airborne radioactive contaminants during the development of the atomic bomb (the Manhattan Project). Nobel Laureate, Irving Langmuir, recommended test methods to filter out these radioactive particles. He identified 0.3 micron size particles to be the most difficult and concerning.

Modern standards require that a HEPA air filter must remove at least 99.97% of particles with a  diameter is greater than 0.3 μm (micrometres or microns).  This means HEPA filters capture pollen, dirt, dust, moisture, bacteria (0.2-2.0 micron), viruses (0.02-0.3 micron), and submicron liquid aerosols (0.02-0.5 µm). 

HEPA filters with photocatalytic oxidation (PCO) also capture microorganisms, like Aspergillus niger, Penicillium citrinum, Staphylococcus epidermidis, and Bacillus subtilis.  They are also able to capture floor dust containing Bacteroidia, Clostridia, and Bacilli and even some viruses and bacteria which are less than 0.3µm.  However, some HEPA air purifiers do not remove smoke and fumes.

HEPA filters are commonly used in vacuum cleaner bags, air conditioning units and other applications that require contamination control, such as hospitals and laboratories as well as  homes, vehicles and for the manufacture of integrated circuits, disk drives, medical devices, semiconductors, aerospace, nuclear, food and pharmaceutical products.

Hoover released a vacuum cleaner with a HEPA filtration bag in the USA in 1960 and now most modern vacuum cleaners can be fitted with HEPA filter bags.