Vacuum cleaner
A vacuum cleaner is a device that uses an air pump to suck up dust and other small particles of dirt, usually from carpeted floors.
Most homes with carpeted floors possess a domestic model for cleaning.
The dirt is collected by a filtering system or a cyclone for later disposal.
History
The first hand-powered cleaner using vacuum principles may have been the "Whirlwind", invented in Chicago in 1865–unfortunately, its technical details seem to be lost with time. Subsequent varieties persisted throughout the 19th century, in all manner of shapes and sizes.
The first electrically-powered cleaner was invented by two men at about the same time. The first was H. Cecil Booth, a British engineer.
He noticed a device used in trains that blew dust off the chairs, and thought it would be much more useful to have one that sucked dust.
He attempted to test the idea by sucking the dust out of a dinner chair with his mouth. He nearly choked, but realised the idea could work.
He patented it in Britain, and created a large horse-drawn vacuum cleaner that would park outside a building to clean it.
Booth never had great success with it, however.
The other inventor, in the United States had much better luck.
In 1906 James Murray Spangler, a janitor in Canton, Ohio, jury-rigged a vacuum cleaner out of a fan, a box, and a pillowcase. He patented it in 1908 and eventually sold the idea to his cousin's "Hoover Harness and Leather Goods Factory."
Hoover remains one of the leading manufacturers of household goods including cleaners, and Hoover became very wealthy from the invention.
In Britain, Hoover has become so associated with the manufacture of vacuum cleaners that "Hoover" is virtually a synonym of vacuum cleaner, indeed many people will often refer to their "hoover" and "doing the hoovering" even if the machine has been made by another manufacturer.
For many years after their introduction, they remained an expensive luxury item, but after World War II, vacuum cleaners became ubiquitous amongst the rising middle classes of the United States and, gradually, the rest of the West. They tend to be more uncommon outside of the West because in many parts of the world, wall-to-wall carpeting is uncommon and most homes have tile or hardwood floors.
Configurations
Two general configurations for vacuum cleaners have emerged as the standard for domestic use.
"Upright" vacuum cleaners have the pump mounted directly above the suction outlet, with the bag mounted on the handle which rises to approximately waist height.
Upright designs usually employ motor-driven mechanical beaters to help disturb dust to be vacuumed up. "Canister" designs instead have the motor and bag in a separate unit, usually mounted on wheels, to the vacuum head, which is connected by a flexible hose. Upright units, mainly due to the effects of the beaters, have been shown in tests to be more effective, but the lighter, more manoeuverable heads of canister models are popular.
Some upmarket canister models have "power heads", which act as mechanical beaters, but they are quite uncommon.
Most vacuum cleaners are also supplied with a variety of attachments which allow them to be used to vacuum places unreachable with the normal head.
Other configurations exist. Some commercial vacuum cleaners are designed to be carried on the back.
Centralized home vacuum systems connect a canister, installed in a central location in the house, to each room via pipes, which only require a lightweight suction hose and head to be carried from room to room. Small hand-held vacuum cleaners, either battery-operated or electric, are also popular for cleaning up spills.
Vacuum cleaners working on the cyclone principle became popular in the 1990s. The air is forced around at high speed in a tighter and tighter circle inside a vessel. The dust particles are thrown to the outside of the vessel by centrifugal force, and clean air from the middle of the vortex is expelled from the machine.
In early 2000 several companies developed robotic vacuum cleaners.
Some examples are Roomba, Trilobite and feet per minute (CFM) or cubic metre per second (m³/s)
- air speed, in miles per hour (mph) or metre per second (m/s)
- suction, vacuum, or water lift, in inches of water or pascal (Pa)
The suction is the maximum pressure difference that the pump can create. For example, a typical domestic model has a suction of about 20 kPa. This means that it can lower the pressure inside the hose from normal atmospheric pressure (about 100 kPa) by 20 kPa, resulting in a pressure of 80 kPa. Therefore the higher the suction rating, the more powerful the cleaner. One inch of water is equivalent to about 249 Pa; hence, the typical suction is 80 inches (2 m) of water.
The power consumption of a cleaner, in watts, is often the only figure stated. This does not indicate how effective the cleaner is, only how much it will cost to supply with electricity.
The amount of this power that is converted into airflow at the end of the cleaning hose is sometimes stated, and is measured in air watts.
This is calculated using the formula:
<math>\begin{matrix}cleaning\;power\;(air\;watts) &=& {{airflow\;(CFM) \times suction\;(inches\;of\;water)} \over 8.5} \\ \\
&=& {airflow\;(m^3/s)\; \times suction\;(Pa)\;}\end{matrix}<math>
See also
