There are a whole host of ways to pressuize gas from atmospheric pressure to a whole range of low, medium, high and ultra high pressures. As a result of varying demands to compress gas, whether it be air or another gas – a number of compressor designs have emerged to suit each application perfectly.
This page will serve as a guide to the different air compressor types and their applications!
Table of Contents
- What Types of Air compressor Are There?
- Types of Positive Displacement Air Compressors (Constant Flow Compressors)
- Types of Dynamic Compressors (Constant Pressure Compressors)
- What Are the 3 Most Common Types of Air Compressors?
- How Do I Choose the Right Type of Air Compressor?
- Additional Reading
What Types of Air compressor Are There?
Air compressors however can be broken down into types in several ways. This probably needs a diagram to explain it more clearly.
There are 2 main categories of air compressor:
- Positive Displacement (Constant Flow Compressors)
- Dynamic Compression (Constant Pressure Compressors)
Types of Positive Displacement Air Compressors (Constant Flow Compressors)
Within the positive displacement air compressor category, there are:
- Reciprocating Air Compressors (Piston Air Compressors)
- Rotary Screw Compressors
- Rotary Vane Compressors
- Scroll Compressors
Reciprocating Air Compressors
Reciprocating air compressors are positive displacement piston type air compressors that suck in air into a chamber and compress it. Read more about reciprocating air compressors here.
Rotary Screw Air Compressors
Rotary screw air compressors work by generating compression continuously at the rotary screw drive air end of the compressor. Air enters the unit at the inlet port of one of the two large screws rotating against one another, also known as the rotors or rotary screws.
This air then moves down the length of the screws and compresses the air towards the outlet due to the air gaps in the rotors getting smaller and smaller. Read more about rotary screw air compressors here.
Rotary Vane Air Compressors
Typically an electric motor that rotates the rotary vane shaft, the vanes to draw in free air, and compress it as they rotate, generating compressed air power. Read more about rotary vane air compressors here.
Types of Dynamic Compressors (Constant Pressure Compressors)
Within the Dynamic Compression Air Compressor category, there are:
- Centrifugal Air Compressors
- Axial Flow Air Compressors
Centrifugal Air Compressors
Centrifugal compressors draw air into the centre of their rotating impeller using its radial blades. The blades essentially produce a pressure variation very similar to an airfoil of a spinning propeller on an aircraft or wind turbine.
The centrifugal compressors are built in stages, and each stage has a part to play in the overall pressure increase of the system. Read more about centrifugal air compressors here.
Axial Flow Air Compressors
Axial compressors are typically made up of many alternating rows of rotating (rotors) and stationary (stators) blades. The blades are similar to that of an aircraft wing as they have small airfoil cross-sections.
Jet engines are actually extremely large examples of axial flow air compressors – in their case using the compression to generate thrust. A bit more than your commercial variety axial flow air compressor! Read more about axial flow air compressors here.
What Are the 3 Most Common Types of Air Compressors?
The 3 most common air compressor types you will come across in a wide variety of industries are:
- Reciprocating air compressors
- Rotary screw air compressors
- Centrifugal air compressors
How Do I Choose the Right Type of Air Compressor?
When deciding which of the above is best suited to you there are a number of factors you must consider which include:
- Air Quality (oil-lubricated vs oil-less)
- Energy Efficiency
- Additional Features
Air Quality (oil-lubricated vs oil-less)
You first of all must consider whether you want an oil-lubricated or oil-less compressor. Using an oil-lubricated compressor may create problems in clean manufacturing environments as the fumes may contaminate the air and result in damage to manufacturing processes. Oil-less compressors greatly reduce this risk.
Though oil-less compressors tend to be more expensive, they are the only option for clean manufacturing. They also boast the benefit of having a lower running cost due to parts not needing to be changed as often as oil-lubricated compressors.
Oil may still be needed to lubricate an oil-less machine but the key part is the inner workings contain a different sealing mechanism to oil-lubricated compressors so that no oil gets in the actual compressor.
Getting the most energy efficient air compressor is worth the extra initial costs if you’re planning a long construction project. Now let’s look at fixed and variable speed compressors.
Fixed speed compressors constantly churn at the same rate, the problem being that when the unit slows down, the motor continues to run until the machine comes to a full stop. This cool-down period causes energy to be wasted without power being generated.
Variable speed-driven (VSD) compressors save energy and of course money, by either increasing or decreasing output on demand.
Another option, if efficiency and energy savings are your main goals are using a natural gas unit. On top of their operational efficiency, they also boast greater heat recovery capabilities than electric compressors.
You must consider whether you wish to be able to transport or move the compressor to different locations. Small, lightweight compressors are far easier to transport and can still deliver the energy you need. They may not be as powerful as larger compressors but they’re perfect for smaller projects like tire inflation, airbrush or other pneumatic tools at home.
If you have any questions regarding the different types of air compressors then please leave a comment below with a photo if applicable so that someone can help you!