If you are dying to know how a vacuum cleaner works, you have come to the right blog: it is physics 101. I know you see demonstrations on TV ads for various unique models, but we will go with a basic one.
Assuming we are talking about an upright vacuum of typical size, you first must know the meaning of suction. This is the principle behind the wonderful machine. Turn it on and you will see. The motor is attached to a fan with angled blades which forces air forward as it turns. It reaches the exhaust port where the density of particles (called air pressure) causes a pressure drop behind the fan.
So far so good? Continuing on: now the air pressure level drops behind the fan to a degree below the level outside the vacuum, thereby creating suction within the machine. The air in your room being cleaned enters the vacuum through an intake source (your assorted attachments) since the pressure outside is greater than inside. Got it! Normally there is an on-going, constant stream of air that moves through the attachment and then out the exhaust port.
We come now to the physics principle of friction which explains how the air collects dust and carpet debris. Here’s what happens: the moving air particles “rug” against loose dirt and this friction carries the material into the machine’s innards. The debris has to be light enough for the amount of suction. Your vacuum might have rotating brushes at the intake site to grab onto carpet lint and dust.
Now what? Here’s where the bag comes into play. The dirt-filled air reaches the exhaust port and passes through the bag which is fabricated out of cloth or paper (a porous material). This is the air filter part of the system. The bag contains tiny holes that let the air pass through easily, but they are too small for even the most aggressive debris which remains behind. Air out, dirt in. It’s that simple.
Bags are located in various sections of the vacuum according to its specific design, and it doesn’t matter as long as it is in the right pathway between intake and exhaust. Upright cleaners are different than compact versions or canister vacuums. As such, the suction capability will vary. It depends on the power of the fan (good speed) and any blockage in the air passageway. If there is too much to vacuum as on a construction site, and the bag fills too quickly, there may be too much resistance for an ordinary model.
Another factor in suction optimization is the opening at the end of the intake port or attachment. Bernoulli’s principle states that when air speed increases (due to a smaller vent), pressure decreases. Greater suction arises from a drop in pressure at the intake port. The moral of this story is that narrow attachments are better at picking up heavy particles.
These are the basics, my friends. I could go on about wet/dry and central system vacs, but we are out of time and space. More next time.