How Does a Vacuum Cleaner Separate Dust from Air?

Updated on May 10, 2022 by Joseph D. Nielson

Table of Contents

Your vacuum cleaner is the MVP of your cleaning routine. Dust, Fido’s fur, and those chip crumbs that fall between the couch cushions are no match for this powerful cleaning tool. It sucks up the crud that collects in your home with one quick sweep over your floors and furniture.

Your vacuum cleans your house so easily, you don’t even have to think about it. But that doesn’t stop us from wondering how it manages this massive job.  

Inquisitive minds want to know: how does a vacuum cleaner work? 

Well, you’re in the right place. Today, we’re breaking down the parts of a vacuum cleaner to reveal how this appliance works, once and for all.

How Does a Vacuum Work — Physics Behind the Appliance

Don’t worry — we’ve broken this physics lesson into simple terms. We promise there isn’t going to be a test later. 

The unassuming vacuum relies on a principle of fluid dynamics called Bernoulli’s Principle [1]. 

According to Bernoulli’s Principle, the faster air moves, the lower the air pressure becomes. Its opposite is also true; as air slows down, the pressure increases.

The nifty thing about air is that it’s always trying to strike a balance. So, when a high-pressure area exists, air naturally flows to where the pressure is lower in an attempt to even things out.

Vacuums: A Balancing Act of Air Pressure

Why does this movement matter? The changing air pressure inside your vacuum cleaner is the mechanism behind its suction. 

In other words, Bernoulli’s Principle is why your vacuum sucks. 

There’s an electric motor inside every vacuum — whether you’re using a robotic vacuum cleaner or a manual Hoover. When turned on, the electric motor draws in air at incredible speeds, creating a low-pressure pocket inside the machine that’s at odds with the pressure outside the machine.

Under Bernoulli’s Principle, the higher air pressure outside the appliance must replace the low-pressure air inside, so it comes rushing in.

Of course, it doesn’t enter the vacuum alone. The force and speed of its travel are strong enough that it carries dirt, dust, and other debris from your home. 

Vacuum Cleaner Parts and Functions

Now that we understand the basic physics behind suction, it’s time to move onto the next part of the lesson.

A vacuum needs more than an electric motor to work. It relies on several different components to harness all that suction power into a lean, mean cleaning machine. 

Below, we’ve listed the most important parts of a vacuum cleaner that make it all possible. 

Air Intake Port

The air intake port is the opening where the air and dust enter the vacuum cleaner. It may look different depending on the type of vacuum you have. 

Upright and wet dry vacuums tend to have them attached to the bottom part that runs along the floor. Portable vacuums may have an air intake port located in the floor tool attached to the vacuum by a long hose. 

Brushes, Hoses & Accessories

Whether the air intake port is at the bottom of the machine or in the floor tool attachment, it’s usually accompanied by brushes. These brushes gently agitate carpet and upholstery fibres to release ground-in dirt and grime. 

Many vacuum cleaners also come with hose accessories that help you tackle specific messes and locations, like pet hair or hard-to-reach nooks and crannies. 

Electric Motor & Fan Blades

An electric motor powers a circular piece of machinery equipped with metal or plastic fan blades. These fan blades rotate rapidly when you turn on your vacuum, forcing the air inside the machine due to Bernoulli’s Principle.

Dust Collector

Upright, portable, wet dry, and more — you can split all these vacuums into two basic dust collection categories: bagged or bagless vacuum cleaners

A bagged appliance collects dust in a vacuum cleaner bag. 

This bag is usually made from paper or cloth that lets air pass through its material easily while trapping dust inside. If you have a bagged appliance, you have to replace these bags every three months or when it’s full — whichever comes first. 

Bagless vacuum cleaners collect dust in a plastic container. 

Air flows through these containers in a cyclonic motion before it escapes, but not before it traps dust and dirt inside. You don’t have to replace containers, but you do have to regularly empty them when they’re full. 

Water and/or Formula Tank

Now, you won’t find this component in every vacuum cleaner. A water tank is only a feature of vacuum mop duos. 

These appliances usually have two tanks — one tank for clean water that gets injected into your carpets and another tank to collect the dirty water extracted from your carpet.

You’ll want to think about the size of these tanks carefully when choosing a vacuum and mop combo. How much water they hold will determine how big of a room you can clean without dumping the dirty water tank. 

Air Filter

Today’s vacuums are equipped with at least one air filter at the intake and exhaust. This filter captures any dust or debris that manages to escape a bag or container. 

Many models use a High Efficiency Particulate Air filter in these locations, or a HEPA filter, for short. A HEPA filter is one of the strongest air filters on the market. 

According to the Environmental Protection Agency, it removes 99.97% of dust, pollen, mold, bacteria, and tiny airborne particles [2]. As a result, HEPA filters aren’t just for vacuums. They’re used in a variety of appliances, including air purifiers. 

Exhaust Port

All that air has to go somewhere. Once it flows through the previous parts of a vacuum cleaner, it escapes through the exhaust port and back into your home. Exhausting air is one of the culprits behind bad vacuum smells.

Cyclonic Vacuum Cleaner: How It Works

Remember our brief description of bagless or cyclonic vacuums? A cyclonic vacuum cleaner whirls air around the plastic dust collection container in a circle, much like a cyclone or air vortex.

Inside a cyclonic vacuum cleaner, centrifugal forces act on the dirt and debris that you pick up from your floors, separating it from the air flowing through your appliance. As air flows in circles, it drops the debris into the dust collection container before escaping through the exhaust port. 

Multi-cyclone vacuums follow this process over and over again by forcing the air through several smaller cyclonic separators. 

These more complex cyclonic dust collection systems create stronger centrifugal force, which means it separates more dust before the final push through your HEPA filter and exhaust port. 

The result? A cleaner home and no stinky exhaust. 

man in pyjamas using vacuum cleaner on a painted parquet floor

Frequently Asked Questions

Just because we answered the big one (how does a vacuum work?) doesn’t mean we’re done yet. We know our readers have a lot more questions about this appliance, so we’re answering them below.

Why is a Vacuum Cleaner Dust Grey? 

Why is it that all that stuff sucked up from your floors always winds up being grey? It’s because dust and allergen particles are so small they scatter light. To the naked eye, this scattering looks grey.  

What Are 10 Uses of Vacuum Cleaner? 

1. Allergen Buster: Your vacuum helps you control your allergies by removing common allergens like dust, pollen, and pet dander from your home.

2. Pet Hair Remover: You can even buy a special attachment to groom your dog or cat — if they let you! 

3. Bug Deterrent: If what the cat dragged in was fleas, use your vacuum to remove the infestation. Research shows vacuuming kills 96% of adult fleas and 100% of younger fleas [3].

4. Laundry Sidekick: Capture lint from deep inside your dryer to remove this fire hazard from your home.

5. Crumb Catcher: Save yourself the chore of sweeping by vacuuming your floors free of crumbs instead. With the right attachment, you can get into hard-to-reach areas that you can’t easily clean by hand. That includes your oven, microwave, and toaster — just make sure they’re unplugged before you start.

6. Deodorizer: Take care of nasty smells by sprinkling baking soda on your carpets, furniture, and mattress before vacuuming it up. For an extra fresh boost, soak a cotton ball in your favourite essential oil and place it in your dust collection container. 

7. Floor Cleaner: Wet-dry vacuums are convenient two-in-one machines that vacuum and wash carpets and hardwood. Take it one step further with a robot vacuum and mop, and the only work you have to do? Pressing the ‘on’ button.

8. Car Detailing: Bring your vacuum to your car to remove those crumbs collecting in your cup holder or the dirt from last weekend’s mountain biking trip. 

9. Find Lost Items: Dropped an earring behind the loveseat? Your vacuum can help you recover it. Attach a piece of cheesecloth or pantyhose to the end of your vacuum hose accessory. The fabric will stop the small item from getting sucked into the machine.

10. Fix Carpet Dents: Do you have dents in your rug after rearranging the living room? Place an ice cube over the dent and let it melt. The water will soften the carpet fibres, so they’ll return to their original shape when you vacuum over them. 

woman bending down to turn on a robotic vacuum cleaner

How Does a Dyson Vacuum Cleaner Work? 

A Dyson vacuum cleaner is a brand that makes multi-cyclonic vacuums. It relies on six layers of air filtration in an air-tight system to create less exhaust.   

How Does a Pool Vacuum Work? 

A pool vacuum works much like the vacuum in your home. Bernoulli’s Principle doesn’t just apply to air but pool water, too. Thanks to the negative pressure caused by the machine, it can draw in water and debris. The pool vacuum forces water through its hose, collects dirt, and filters water back into the pool.

How Does a Vacuum Work — Solved!

And there you have it, now you know how your seemingly simple vacuum does its job. Some pretty complex mechanisms are at work to control the air pressure in and outside your home. 

Whether you understand it or not, your vacuum works just the same. Turn it on, and it’ll take care of life’s messes, big and small. Next, take a look at these hoover vacuum tips to keep your home fresh and clean.


[1] What is Bernoulli’s Equation Khan Academy

[2] What is a HEPA Filter? United States Environmental Protection Agency

[3] Cat Fleas’ Journey Into The Vacuum Is A “One-Way Trip” Ohio State University 

Joseph and Family
About Joseph D. Nielson

Former journalist and editor for various press groups, I now dedicate my time to reviewing products for the home and family life. When I get time to myself, I enjoy rock climbing, taking my dirt bike for a rip, and most importantly providing my family with the best home possible!