How do vacuums create suction

Since not all of these particles are trapped by the bag or canister, the vacuum cleaner passes the air through at least one fine filter and often a HEPA High Efficiency Particulate Arresting filter to remove almost all of the dust. Only now is the air safe to be breathed again. The power of a vacuum cleaner is determined not just by the power of its motor, but also the size of the intake port, the part that sucks up the dirt. The smaller the size of the intake, the more suction power is generated, as squeezing the same amount of air through a narrower passage means that the air must move faster.

This is the reason that vacuum cleaner attachments with narrow, small entry ports seem to have a much higher suction than a larger one. There are many different types of vacuum cleaner, but all of them work on the same principle of creating negative pressure using a fan, trapping the sucked-up dirt, cleaning the exhaust air and then releasing it.

The world would be a much dirtier place without them. Related reading: Household cleaners may make kids overweight. Originally published by Cosmos as How do vacuum cleaners work? Menu open Search open Nation choice page link. Search close Search X Search. Sort by Sort by Recent Popular. OK Cancel. Without question, there was great need for high-powered, but maneuverable, cleaning devices. So what exactly is inside your vacuum that makes it work? The Suction Motor. The first component is one of the most important parts.

The suction motor creates vacuum pressure and suction by rotating a motor fan. In general, a vacuum is created by starting with air at atmospheric pressure within a chamber of some sort. At atmospheric pressure, the gas molecules are very close together; and as they are in constant motion, the distance between molecule-to-molecule collisions is very short.

This distance is known as mean free path. As molecules are removed by the vacuum pump, the distance between collisions becomes greater and greater. Figure 3 shows the mean free path as a function of pressure.

As molecules are removed, there are fewer other molecules for a given molecule to collide with the distance becomes longer and longer as the pressure is reduced. This concept, though fairly obvious, is important in understanding vacuum technology in that the behavior and flow of molecules is almost the whole subject. When the pumpdown is started at atmospheric pressure, the gas molecules are in a flow regime condition called viscous flow.

This means that the constant molecule-to-molecule collisions will cause the population of molecules within a given volume to even out immediately when some molecules are removed. This behavior is what most people think of as the effects of pressure differential since there seems to be a driving force to move molecules.

This can be seen more clearly as we begin to remove molecules from the chamber. Starting from atmospheric pressure, molecules are most commonly removed with a mechanically actuated positive displacement pump of some sort. This can be anything from an oil-sealed rotary pump to an oil-free diaphragm, piston, or scroll pump. The overall idea is the same in that the gas in the chamber to be evacuated is expanded into a fixed volume where it is isolated and then mechanically compressed to a point where it is expelled into another stage or directly into the atmosphere.

The exposure and subsequent isolation of the molecules in the chamber to the fixed volume continues at a high rate and more and more molecules are removed. As more and more molecules are removed, the mean free path increases and that results in a slightly longer and longer time to achieve equilibrium in molecular population so that the apparent driving force of pressure is reduced, and.

Fewer and fewer molecules are removed with each cycle of the pump since there are fewer molecules available to be pumped. During this process of molecular removal, the makeup of the air as gas mixture remains pretty much the same in terms of relative ratios as is shown in Figure 2, and the total molecular depopulation continues as above until the mean free path becomes long enough that a given molecule is more likely to impact the chamber wall than another molecule.

At this point the entire behavior of the molecules changes and the process enters another flow regime entirely. Since the molecular behavior is based on the effects of mean free path which is a function of the molecular concentration, the physical size of the container chamber begins to come into play.

The tiny holes in the bag are large enough to let air particles pass by, but too small for most dirt particles to fit through. Thus, when the air current streams into the bag, all the air moves on through the material, but the dirt and debris collect in the bag.

You can put the vacuum-cleaner bag anywhere along the path between the intake tube and the exhaust port, as long as the air current flows through it. In upright vacuum cleaners, the bag is typically the last stop on the path: Immediately after it is filtered, the air flows back to the outside.

In canister vacuums , the bag may be positioned before the fan, so the air is filtered as soon as it enters the vacuum. Using this basic idea, designers create all sorts of vacuum cleaners, with a wide range of suction capacities.

In the next section, we'll look at a few of the factors that determine suction power. Read vacuum cleaner reviews and compare prices at Consumer Guide Products before you buy.

In the last section, we saw that vacuum cleaners pick up dirt by driving a stream of air through an air filter the bag. The power of the vacuum cleaner's suction depends on a number of factors. Suction will be stronger or weaker depending on:. At the most basic level, this is all there is to a vacuum cleaner. Since the electric vacuum's invention a century ago, many innovative thinkers have expanded and modified this idea to create different sorts of vacuum systems.

So far, we have looked at the most typical types of vacuum cleaners: the upright and canister designs, both of which collect dirt in a porous bag. For most of the history of vacuum cleaners, these have been the most popular designs, but there are many other ways to configure the suction system.

We'll look at some of these in the next section. The first vacuum cleaners, dating from the mid s, used hand-operated bellows to create suction. These came in all shapes and sizes, and were of minimal help in daily cleaning. The first electric vacuum cleaners showed up in the early s, and were an immediate success though for many decades they were sold only as a luxury item.

One very popular vacuum-cleaner design from this era is finding a resurgence in popularity today. This design, the central vacuum system , turns your whole house into a cleaner. A motorized fan in the basement or outside the house creates suction through a series of interconnected pipes in the walls. To use the cleaner, you turn on the fan motor and attach a hose to any of the various pipe outlets throughout the house. The dirt is sucked into the pipes and deposited in a large canister, which you empty only a few times a year.

Liquid material would soak paper or cloth filters, so these cleaners need a different sort of collection system. The basic design is simple: On its way through the cleaner, the air stream passes through a wider area , which is positioned over a bucket.

When it reaches this larger area, the air stream slows down , for the same reason that the air speeds up when flowing through a narrow attachment. This drop in speed effectively loosens the air's grip, so the liquid droplets and heavier dirt particles can fall out of the air stream and into the bucket.