Air compressors are tools that send air into a storage tank from the compression system and then hold it there until the compressed air is ready to be used for a wide variety of uses. That’s a basic rundown of what an air compressor is, but what if you want to have a deeper understanding of just how these tools work? Having a deeper understanding and better appreciation of how the tools you use work can come with great benefits.

Today, we’re going to be taking a close look at how an air compressor works. Although these machines might seem simple on the outside, there’s actually a lot going inside of these machines that allows them to work in the way they do. We have a bit of ground to cover, so without any further ado, here’s everything you could possibly want to know in regards to just how an air compressor works.

Primary Function

what is an air compressorThe primary function of an air compressor is to force a continuous stream of excess air into some sort of receptacle – generally a storage tank of some sort. Once enough air has been put into this storage tank and the tank in question has reached its limit, the compressor then shuts itself off. At this point, the air is then held in the storage tank until you are ready to use it.

The air that’s being stored in the storage tank is a form of kinetic energy, and it can be used for a wide array of functions (e.g. filling up the air in a tire, using an attachment to blow sawdust off of your work area, etc.) However, once you begin using this air, it will start depleting from the storage tank. Once the air has been used up, the compressor will then turn on again and begin to fill up the storage tank. This is referred to as re-pressurizing the tank, and it will take place each and every time that you use enough air.

Compressing Air

As you already know, the main purpose of an air compressor is to compress air for later use. With that in mind, just how does this compression take place?


The air compressor itself takes in air and forces it into its respective storage tank. As this takes place, the pressure that is inside the tank constantly increases and gets more and more powerful. This keeps going on until the pressure in the tank reaches its maximum limit. Once this limit is reached, the air compressor itself will turn off, and the air in the tank will be ready for your use whenever duty calls for it.

As you start using the air that’s stored in the tank, the pressure will begin to decrease. As this continues, the air compressor itself will need to turn on once again in order to push more compressed air into the tank. You can continue to use the air in the tank while the air compressor is pushing more air into it, or you can decide to let it fill up again. There’s not necessarily a right way to go about this, as it really is just more of a personal preference.

Displacement in Air Compressors

When an air compressor gets air in it, something called displacement takes place. Displacement is essentially just the act of air getting pressurized into the compressor and is what allows it to be so powerful when it comes time to use. Displacement with air compressors can take place via a variety of different ways, with the two main ones being positive displacement and dynamic displacement. The type of displacement that takes place is ultimately dependent on the kind of air compressor that you’re using.

Types of Displacement

There are two main ways for displacement to take place – positive and dynamic displacement.

When air compression takes place with positive displacement, air is forced directly into a chamber. This force takes place by decreasing the overall volume of the chamber to compress the air in question. There are three different variations – piston type, rotary screw compressors, and vane compressors. Each of these different types serves their own, unique purpose, but all achieve the same overall goal.

The second type of displacement comes in the form of dynamic displacement. Dynamic displacement occurs by either a centrifugal or axial compressor. In this case, a rotating component inside the compressor takes the pressure energy and completely converts it. From here, the centrifugal force that’s found in these types of compressors – created by spinning impellers – is able to both accelerate and decelerate the air inside the compressor. This action is able to pressurize the air.

Cooling Off


Due to the way that all air compressors operate, they have a tendency to heat up. However, this doesn’t create a situation in which you should be alarmed! This is a perfectly natural part of the air compressing process for these machines, but thankfully, air compressors generally come equipped with built-in cooling methods to regulate the excess heat that is created.

More specifically, these cooling systems usually use either water or air to cool the air compressors. Rotary type compressors sometimes use oil to cool themselves down, but this is the only real exception to the norm.

Additionally, the atmosphere or environment that the air compressor is operated in also contributes to the cooling process. So, storing your air compressor in an area that has a tendency to be on the cool side can be a great deal of help when trying to keep it at a cool and safe temperature.


Air compressors can serve as incredibly powerful tools, so it’s important to have a basic understanding of how they work. Although there’s a lot that goes into their operation, it really isn’t all that difficult to wrap your head around.

Air compressor tanks send excess air they gather into storage tanks, and these tanks hold the compressed air until you’re ready to use it for whatever kind of project or task you have at hand. Using this air will cause the compressor to turn on once again and send more air into the storage tank.

Displacement is the process that takes place when the air is pressurized. The type of displacement that takes place will depend on the kind of air compressor that you’re using. While the actual technical details might be a bit difficult to understand, the overall process is actually easy to comprehend. And hopefully, now that you’re done reading this article, you have a better understanding as to just how your powerful air compressor actually works.