How does a vacuum cleaner work and how is it able to suck like that?
In: Engineering
A vacuum cleaner basically has a powerful fan in it that blows air out of the cleaner. Now, when there’s more air on the outside, there has to be less on the inside, which is the case. We will need this again later.
Air is not weightless. The more you stack, the more weight pushes down on the part that’s all at the bottom. This is for example why the air is thinner on mountains where there’s just less air pushing down and creating pressure. This pressure is called atmospheric pressure and at sea level 1 Bar.
Now back to the vacuum cleaner. There’s now air “missing” inside the machine, but the atmospheric pressure that exists even in your house is still trying to compress the air below it. The air below it doesn’t want to be compressed and looks for places to go, which happens to be your vacuum cleaner. This flow of air, also called wind, now blows dust into the vacuum cleaner where it’s collected in a bag.
The extraction fan in a vacuum cleaner reduces the pressure inside the canister. Atmospheric air, which is at an absolute pressure of about 14.7 psi, is driven by that pressure up the hose towards the evacuated canister, and carries with it all of the debris you are trying to clean up. As atmospheric pressure is near constant, you can never get more pressure differential than that, so what makes one vacuum cleaner more powerful than another is simply how much air it can move. Powerful vacuums can maintain that pressure differential even with large bore hoses.
Basically it’s like a ventilator just turned around. A ventilator blows air in a specific direction while taking in air from any direction. If you put a pipe or a tunnel at the entry of a ventilator the air will get sucked into the tunnel. If you then form the tunnel in a way where it get smaller at one end th air gets sucked even stronger.
This is basically what vacuum cleaners do. They have a turned around ventilator inside and some filters.
Vacuum is a box. You remove air from box with fan that blows it outside. Air in the box gets replaced with air from outside via the hose. Air rushes in and brings dirt with it.
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