Vacuum cleaners

Last updated: May 9, 2010.

Even when your house is clean, it's absolutely filthy! That's because most of the dust and dirt in your house is way too small to see. Fortunately, most of us can live without knowing this kind of truth about our homes; a quick run around with the vacuum cleaner is enough to keep us happy. Twenty-first century homes are packed with dozens of appliances and gadgets, but vacuums are one of the few most of us simply couldn't live without. We all know vacuums suck up dirt—but how exactly do they work? Let's take a closer look!

Photo: A Dyson cleaner, like this one, shows you just how much dirt it's picking up in its transparent bin. The dust and hair tends to swirl around thanks to the machine's "cyclonic" action. Other popular makes of vacuum cleaner include Hoover, Miele, Electrolux, Panasonic, and Bissell. Most of these firms now make bagless cleaners—the revolutionary idea Dyson popularized in the 1990s. Who makes the best vacuum cleaner? It's a matter of opinion. Read plenty of customer reviews online before you buy!

How does a vacuum cleaner work?

The name "vacuum cleaner" is a bit of a giveaway when it comes to understanding how your machine works: vacuum cleaners work by suction If you've ever tried that cleaning trick with a tissue paper and a comb, you'll know how effective suction can be for removing dirt. If not, try it now! Wrap a piece of tissue paper around a comb. Breath out as far as you can and hold your breath. Place the comb and paper against your mouth. Now lean against a dusty armchair and press your mouth and the comb against it. Breath in sharply so, effectively, you are breathing straight through the comb. Take the comb away from your mouth and inspect the tissue paper. See how dirty it is!

Photo right: Vacuum cleaners work just like the comb and paper trick using sophisticated HEPA filters. Left: Take the dust-collecting bin off a Dyson and you can see one of the two HEPA filters (beneath the circular grating). Right: There's a second filter at the top of the dust bin.

What parts are inside a vacuum cleaner?

This is almost exactly how a vacuum cleaner works. In place of your mouth, there's a powerful electric motor attached to a fan that sucks in air. (In a typical cleaner, the motor is about 500-1000 watts, so it uses five to ten times as much energy as a bright electric lamp.) The tissue paper and comb are replaced by foam filters, and there's a dirt bag or a plastic bucket to catch the dust sucked in so you can use the cleaner for some time without worrying about where all the dirt is going. Most cleaners have a variety of other features, including a rotating brush at the front (for beating dirt out of rugs and carpets so it's easier to suck away) and an extension hose (for cleaning stairs, upholstery, ceilings, and other hard-to-reach places).

How do Dyson vacuums work?

Invented in 1901 by a British engineer, the first electric vacuums were simple sucking machines with a brush and suction head at the front, a motor in the middle, and a bag at the top. When you switched them on, the motor whirred into action, sucking in air and dirt and blowing them into the bag. Most vacuums worked this way until the late 1980s, when another British engineer named James Dyson felt it was time to go one better.

The trouble with old-style vacuum cleaners is that they suck in dirty air and blow it directly into the bag. The bag catches the dirt and the relatively clean (but sometimes still dusty) air drifts back into the room. The longer you use a vacuum, the more the bag fills up. As the bag fills up, the amount of empty air it can hold decreases, so its ability to suck in more dirt is gradually diminished. The longer you go without emptying your vacuum, the worse the problem becomes.

Goodbye to the bag

Dyson decided to tackle this difficulty by doing away with the bag altogether. By this time, he was already a successful inventor manufacturing his own plastic garden equipment. His factory in England's West Country was plagued with dust, so he designed a "cyclonic" air filtering device to keep it clean. Using a powerful fan, it sucked in dusty air and spun it around at high speed like a centrifuge. Spinning the dusty air was an effective way to separate the dust out of the air. In a washing machine, the same principle is used to spin water from clothes at the end of the wash cycle. As the drum spins at high speed, the clothes fling against the edge of the drum and the water they contain is forced out through the drum's tiny holes. The same idea proved just as effective in Dyson's air filter. Spinning the air forced the heavy dust particles out through holes in the filter where they could be trapped and collected; the cleaned air could then be piped back into the room. Dyson's machine was so efficient and successful that he wondered why vacuum cleaners didn't use the same idea. He resolved to invent a cyclonic vacuum cleaner there and then.

Photo: A laboratory centrifuge works in a similar way to a Dyson cleaner. Blood loaded into test tubes is spun around at very high speed so it quickly separates into its components. Photo by Sue Sapp courtesy of US Air Force.

Perfecting the invention

Between the late 1970s and the mid 1980s, Dyson built no fewer than 5,127 prototypes of his cyclonic cleaner. By the late 1980s, he was selling a bright pink cyclonic cleaner called the G-Force in Japan. It was large, clumsy, and expensive, but it earned him enough money to develop a more compact, affordable cyclonic vacuum called the DC01. During the mid-1990s, this new machine won countless design awards and soon became Britain's biggest selling vacuum cleaner—and it is now sold worldwide.

Its secret is simple: because there is no bag to clog up with dust and dirt, the machine always sucks with exactly the same power. You still have to empty the dirt bin every so often, but the cyclonic action means a Dyson with a full dirt bin works equally as well as one that's just been emptied.

All this goes to show that, no matter how good an invention appears to be, someone can always make it better! (Talking of improvements, have you seen robotic vacuum cleaners that clean your home automatically?)