If you are interested in understanding more about how an air compressor works, this guide can be a valuable resource. In this guide, you will find details regarding the way that many of the most common air compressor types function internally and what purposes they serve.

A compressor works by forcing air into a pressurized container and then using that pressure to force air through to power tools and machinery. This is the basis of all types of compression and is shared among all the compressor types.

This guide will provide more details on the way compressors work and offer more insight into the different compressor types currently available.

How A Compressor Works

Compressors work by first forcing air into a tank or container and pressurizing it. Once pressurized, the air is forced through an opening in the tank, which causes additional pressure buildup. The engine powers the compressor by turning electrical energy into a form of kinetic energy.

The process is very similar to the way that any combustion engine operates. Once the power has been converted and the pressure has reached the right levels, it can be used to power tools and machinery.

How Different Types Of Compressors Work

The two main types of air compressors are positive and dynamic displacement compressors and both use different methods to achieve compression. They both have their own subcategory of compressor types that utilize either positive or dynamic displacement compression.

The section below will contain more details on the different types of compressors and how they operate.

Positive Displacement

Compressors that use positive displacement use a method that forces air into a chamber where the volume is significantly smaller to compress the air. Generally, positive displacement compressors are much better suited for heavy, industrial workloads.

 There are several types of compressors that utilize a positive displacement method of compression. The section below will discuss these compressors in more detail.

Rotary Screw

Rotary screw compressors utilize internal screws that rotate in opposite directions to trap air and begin the compression process. There is a constant movement that is generated inside the compressor by the screws as they rotate around.

Rotary screw compressors are commonly used in warehouses and for powering large home appliances. They are one of the easiest compressor types to maintain and have a great longevity rating.

Rotary Valve

Rotary valve compressors are very similar to rotary screw compressors but do not utilize screws to begin the compression process. Instead, rotary valve compressors use valves that are mounted on a rotor that rotates inside the compressor.

The air is then compressed between the valves and the casing of the compressor and pushed out through a separate exhaust port. Rotary valve compressors are popular for domestic use and DIY projects.

Reciprocating/Piston Type Single Stage

A piston or reciprocating compressor uses pistons that are controlled by a crankshaft to pressurize gas and air. These types of compressors can be found in two types, single-stage, and two-stage.

The single-stage reciprocating compressor uses a method that handles the compression of air and functionalities on separate sides of the piston. Using this method, the air is drawn in as the piston is forced down and is compressed as the piston is drawn back up.

Single-stage compressors are popular for their affordability and availability for home and DIY use. You can commonly find single-stage compressors at your local hardware store.

Reciprocating/Piston Type Two Stage

A piston or reciprocating compressor uses pistons that are controlled by a crankshaft to pressurize gas and air. These types of compressors can be found in two types, single-stage, and two-stage.

Two-stage reciprocating compressors have two compression chambers that are located on both sides of the piston. These compressor types are generally water-cooled to prevent overheating. Because of this, two-stage compressors have a much better cooling system than most compressor types.

You will typically find two-stage compressors being used in large factory settings. Due to their high costs to purchase and operate, they are not a viable option for home use.

Dynamic Displacement

Dynamic displacement is the second main type of compression method. Compressors that use dynamic displacement to start the compression process utilize a large rotating blade that is engine powered to first generate airflow.

Once the flow of air has begun, the air is then rapidly restricted to raise the pressure and store kinetic energy inside of the compressor. Dynamic displacement compressors are usually used for large warehouses and businesses.

Because of the specialized nature of dynamic displacement compressors, you will likely not be able to purchase one locally. They are not a viable option for home use or for small projects. There are a couple of compressors that utilize dynamic displacement.

These compressors will be discussed in detail in the section below.

Axial Compressors

Axial compressors use turbine blades to generate air and then force it through a much smaller area. They are similar to other compressors that use blades to generate airflow but also utilize a stationary blade to slow the airflow and increase the overall pressure.

These types of compressors are rare and do not have much practical use outside of aircraft manufacturing.

Centrifugal Compressors

Centrifugal, also known as radial compressors, work by first forcing air into the center through a rotating impeller. This air is then forced forward by an outward force. The air inside is slowed by a diffuser which helps to generate more kinetic energy. 

Centrifugal compressors are commonly found in HVAC systems.

Scroll Compressors

Scroll compressors use an orbiting scroll to compress gas and refrigerants. The orbiting scroll is powered by an electric motor that rotates a shaft within the chamber.

This will cause the gas to be captured between the fixed and orbiting scroll. Scroll compressors are considered the quietest and smoothest operating machines out of the five main types of compressors.

Scroll air compressors are another positive displacement type. They are known for leaving the smallest carbon footprint of all of the compressor types. This makes them a great option for industries that hold themselves to high environmental standards.

Scroll compressors

Difference Between Pump And Compressor

The difference between a pump and compressor comes down to the type of material that is being passed through it. A pump is designed to move fluids between two places while a compressor is built to pressurize air and gas so it can be utilized by other tools and machinery.

A compressor will not be able to work with any form of liquid. Many compressors feature an internal pump that is used to help power the compressor. The act of volume reduction to create pressure is what makes compressors different than pumps.

What Drives A Compressor?

Compressor drives are generally belt-driven, meaning that as the motor turns, so does the belt which activates the pump inside the compressor. Belt-driven compressors are much more common and less expensive than the other popular drive type, a direct-drive system.

A direct-drive system has a motor that is attached directly to the crankshaft of the compressor. This allows for more compact designs and easier maintenance. A direct-drive compressor will be much more expensive than a belt-driven one.

That being said, you can expect a direct-drive system compressor to operate much more efficiently due to the amount of power being retained during the transfer to the crankshaft.

Compressor Lubrication Requirements

All compressors require the proper lubrication to function properly. Lubrication is vital to how compressors work and can be broken down into two main categories, splash lubrication, and pressure lubrication.

Splash lubrication utilizes a dipper that is attached to the piston rod that dips into an oil-filled container and then splashes the oil onto both the cylinder and the piston. This provides the proper lubrication for the machine to operate optimally.

Pressure lubrication utilizes a pump that sends oil through several passages that have been drilled inside of the compressor. This process applies oil to specific parts of the compressor. A pressure lubricating system will generally be more expensive but is a more efficient way of lubricating your machine.

There are some forms of non-lubricated compressors that you can consider. These compressors utilize a special coating on their internal components that reduce friction and remove the need for traditional oil-based lubricants.

Non-lubricated compressors typically overheat faster and more often than lubricated ones. This makes them not ideal for large factory settings or heavy, continuous usage. Non-lubricated compressors are typically found in settings where clean air is a requirement like the food or electronics industry.

How Does A Compressor Regulator Work?

A regulator is attached to the outlet of your compressor’s air tank and features an adjustable knob and a built-in pressure indicator. The knob can be used to raise and lower the pressure by using a spring to open and restrict a valve that blocks airflow.

Single-stage compressors max out at around 125 psi. Once this pressure threshold has been reached, a pressure switch will be released to stop the motor and the compression process until the pressure is at an acceptable level.

In most cases, users wish to set this pressure threshold themselves to ensure the cutoff is at the proper levels. You can do this by using a compressor regulator. A regulator will automatically adjust the levels of air that you need to the appropriate levels for both tools and machinery.

A regulator cannot however raise the pressure rating of your compressor beyond what it is specified for. You should consider purchasing a regulator for your air compressor to have more control over the pressure being built up inside of the tank.

Common Compressor Uses

The uses and efficiency of the different compressor types vary based on the job that you are undertaking. It is important to consider the different strengths of the compressor types before you commit to adding one to your setup.

The list below will contain information regarding the common uses for the different compressor types. This will help you decide what compressor type is appropriate for your situation.

Reciprocating Compressor Uses

Reciprocating compressors are best suited for short, flexible jobs involving hand tools that utilize compressed air. Because of the low energy consumption of reciprocating air compressor and their portability, they are ideal for these types of jobs.

You should not use a reciprocating air compressor for jobs that require extended use or for powering heavy-duty machinery.

Rotary Compressor Uses

A rotary compressor is best suited for heavy-duty, prolonged use. They are typically used in construction situations to power jackhammers or sand-blasting machines. These are a much more industrialized compressor type and will often be more powerful than you need for home use.

Centrifugal Compressor Uses

Centrifugal air compressors are best used with heavy equipment. Centrifugal compressors are the most powerful of all the compressor types. This means that you can use it to power even the most heavy-duty and demanding equipment.

These compressors are generally not suited for domestic or DIY use due to their price and size.

Scroll Compressor Uses

Scroll air compressors are best utilized in environmentally conscious work areas and businesses. Because the scroll air compressor runs the cleanest of all of the air compressor types, they have become popular with companies that aim to leave a low carbon footprint.

Scroll compressors are commonly found being used to power dentistry equipment due to their clean air quality.

Final Thoughts

This guide has provided you with all of the information that you need to better understand how compressors work. The information in this guide can be a valuable resource for gaining additional insight into the different types of compressors and how they operate internally.

You can use this guide to figure out how the different compression types work and which one is potentially a good fit for your project or business.

It is important to understand how compressors work before committing to a purchase. Because of the varying uses and methods of compression, being informed of the differences can help you make the right decision when choosing which one is right for you.