Workshops and plants typically use centralized power sources to drive a variety of tools utilizing a mechanical system consisting of belts, wheels, and driveshafts. It was a massive and complicated system, not to mention costly. Nowadays, we’ve figured a way around the belts and shafts. However, there’s still a mechanical system being used to power the tools of the workspace. This system uses air power by pressurizing air as an alternative power source, which is used for various applications, such as powering different air-powered tools (like nail guns, spray guns, etc.) to use them for their respective purposes, and the core device of this system is the air compressor machine.

air compressor for work

Air compressor technology has found its way into a wide variety of applications in our everyday lives. In fact, it won’t be an exaggeration to say that for a lot of us, It has even become a part of our daily lives. Air tools have started being widely used, and to run these pneumatic machines, we need compressors. Air compressors have nowadays become an essential component of the working system, be it in a home garage or any factory environment.

Now let’s come to the point. To run a system, you need to understand the system. You need to know how it works. If you know how a machine works, what is the working principle behind it, then it’ll be much easier for you to understand what is the process of operating the machine, what is necessary for the proper maintenance of the device, or how to improve the performance of the machine.

So, the purpose of this article is to give you a clear idea about how an air compressor unit works. Here, you will find detailed information about the working principle of air compression operations, written in an easily understandable manner.

The basic structure of an air compressor

Drive

The work of this part is to provide the necessary power to run the compressor pump. This can be a gas engine or electric motor.

Pump

This component uses the power received from the drive to inhale the atmospheric air through an inlet valve. Then it uses increased pressure to compress the air. After that, this compressed air goes through a discharge valve and tube into a storage tank for later use.

Storage tank

The purpose of this component is to store the compressed air for later use. It is equipped with a one-way valve, which is called a check valve. This valve prevents the compressed air from applying reverse pressure on the pump.

How does an air compressor regulator work?

A regulator is a piece of equipment that includes an adjustable knob and a pressure indicator. This equipment is attached to the outlet of the air tank of your air compressor. When you rotate the knob counterclockwise, it starts pushing on a spring. This restricts a valve, which reduces the air supply that enters the regulator, thus lowering the pressure. When you turn the knob clockwise, the opposite happens. The spring releases the valve. This allows air with higher pressure air to go through to the output.

how air compressor regulator work

Difference Between a Pump and a Compressor

Many of us get confused between a pump and a compressor. A lot of us think that they mean the same thing. But that is not actually the case.

  • A pump moves fluids (liquids or gasses) between places.
  • A compressor’s work is to pressurize and compress gases (atmospheric air) into a smaller volume and higher pressure and supplying it for various purposes.
  •  A pump may work with liquids, moving them from place to place, but a compressor typically doesn’t. A compressor is used to compress air and utilize the energy of that compressed air.

Different type of air compressors

There are two main types of air compression methods that are used in compressors. To understand the working principle of a compressor, it’s wise to first learn about the different types of compressors and the air compression method they use.

Types of compression

  • Positive displacement air compression
  • Dynamic displacement air compression

Positive displacement air compression

The working principle of the positive displacement compression systems is to inhale the air into the compression chamber, then compress the air by reducing the volume of air through implementing pressure. After the compression is done, the outlet valves open to move the air to the storage tank from the compression chamber by force. Examples of positive-displacement compressors include reciprocating, rotary-screw, piston, vane, and scroll-type air compressing systems.

Reciprocating/Piston compressor

Reciprocating compressors work by using positive displacement. They use pistons, which are controlled by the crankshaft for their downward and upward strokes. The downward strokes of the piston rod inhale the airflow into the chamber, and the upward strokes, move the compressed air stream to the air storage tank.

These types of piston technology based compressors have a comparatively lower output, but they are able to provide a higher pressure output than others. So, these piston-based air compressors are usually found at smaller worksites and aren’t designed for continuous use.

This type of piston air compressor is suitable if you want to compress a small amount of air but implement high air compressor pressure. Also, It is able to dissipate the heat produced during the compressing process.

Teflon piston ring is usually used for non-lubricated compressors of this type. It reduces wear and eliminates the need for lubrication of pistons, rings, and cylinders.

Piston compressors are of two types

  • Single-stage compressors
  • 2-stage compressors

Basically, single-stage compressors use a single phase of compression to compress the air. On the other hand, dual-stage compressing machines carry out another phase of compression along with the first one.

You can click here to learn more about the single-stage and two-stage models, how does a single-stage or a two-stage air compressor works, and the differences between them.

Rotary Screw compressor

rotary screw compressor mechanism

Rotary screw air compressors also use positive displacement. They compress air compression using a system consisting of interlocking screws that inhale the air and then pressurize and compress it in a smaller area.

This is one of the most common types of air compressors. Moreover, It is easier to take care of and is the more preferable choice for continuous use. They generally have industrial-sized engines.

There are two internal screws in a rotary screw compressor. They rotate in opposite directions along with constant movements, and the air gets trapped and compressed between them.

Oil-free rotary screw devices use non-contacting carbon ring seals to prevent any oil from entering the air stream inside of the air compression unit. Also, the sectioned-off coolant on the other side of the seal eases the cooling process. However, these oil-less compressors typically lack the ability to throttle the inlet, which results in heat buildup over time in these types of compressing machines. So, the flooded models are more preferred to the users who need ample supplies.

Vane Compressors

Another compressing machine that uses the positive-displacement compression system is called the rotary-vane compressor. This type of device has a similar working principle to the rotary-screw compressor. But, instead of screws, these positive displacement compressor systems have built-in rotors along with adjustable arrangements of blades.

The blades or vanes are mounted on a rotor, which is rotated inside the cavity. The air is compressed between the blade and its casing. The arms approach the air input and get elongated. This creates a large air cavity. As the motor spins and moves air with it, the arms start getting smaller and approaching the output. This creates a smaller space between the vanes and the round casing, and this reduction of space volume compresses the air. After that, the air is then moved out to a different exhaust port.

This air compressor type is able to deliver specific volumes of air at a high pressure output. Also, it is very easy to use. This is why it’s pretty preferable among the users who need an air compressor for private projects like a home workshop and the most common type of compressing device found in these environments.

The scroll compression technology is an advanced air compression system. It has a mobile and a stationary spiral. These two work together to bring air into the chamber for compression. The volume of the air is reduced within the spirals in order to compress the air. After that, the air is directed to the center of the compressing device to be cooled.

The most significant advantage of these scroll compressors is that the spirals never come into contact with each other. This technology eliminates the possibility of any residual friction or wearing on the working system. Some of the models of this type of compressors require lubricant or oil. But there are many models available out there that can operate without using oil.

Dynamic displacement air compression

Dynamic displacement air compressors work by forcing the air into compression chambers with rotating blades and impellers power by an engine. The inhaled atmospheric air is restricted and pressurized and then stored in the air compressor tank.

Compressors with this compression system have various compressor elements like variable reciprocating pistons, valve head, connecting rods, pistons, crankshafts, eccentric rings, and cylinders.

This air compression system is much faster than the alternative in completing air compressor function and providing compressed air. Furthermore, it is capable of delivering a higher amount of compressed air supply.

Machines with this air compression system are mainly industrial air compressors, preferable for applications that require constant pressure and large volumes of air flow. They are developed to be used in large projects, like to run a factory operation, a steel manufacturing industry, or a chemical plant. Many automobiles also use this technology.

Centrifugal compressors and axial compressors are examples of non-positive displacement air compression system-based compressors.

Axial air compressors

axial air compressors

Axial air compressors have a series of turbine blades. These machines use these blades to force the air through a small area and generate air pressure. This may seem kind of similar to other bladed compressing systems, but that’s not necessarily the case. Axial compressing machines actually operate with stationary blades. Their task is to slow the flow of air and increase the air pressure in the process.

This particular type of compressing machine is not very common. Also, they have limited functionality. They can be seen usually being used in aircraft engines or large air separation plants.

Centrifugal Compressors

centrifugal compressors schematic diagram

Centrifugal air compressors are also called radial compressors. This type of compressor uses a rotating impeller to bring the air into the center. Then this air is pushed forward or outward through centrifugal force. A diffuser is used to slow the flow of air, and thus kinetic energy is generated.

These machines generally use electric high-speed motors. One of the common uses of centrifugal compressors is in HVAC systems.

Final Words

Air compressor is an essential tool in many of our daily lives. This is a handy tool with versatile applications ranging from private projects at home to professional works like a construction project or auto repair.

For those who use this kind of tool, or any type of tool for that matter, it is crucial to know the mechanisms, characteristics, and other details to ensure maximum efficiency, better life expectancy, and controlled energy costs, among other things. And, this article is here to do just that.

By reading this article, you’ll learn about air compressors, their structures, different types of compressors, and their working principles. If you want more information, please check out our other relevant articles, and if you have any specific questions, please do not hesitate to contact us.

Thank you for reading.

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Author

Hi, and welcome to Toolented. My name is Michael D. Sanders. I am a Mechanical Engineer by degree, who is a blogger by passion, and this combination of knowledge and passion is what brought Toolented to life. On my blog website, you will find necessary information about your needed automotive tools, reviews of your potential choices, and comparisons between different types of tools. To learn more click here.

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