We use compressed air in millions of functions – and countless manufacturing and industrial equipment rely on compressed air to function.

So, how is air compressed, what purpose does it serve, and why is this energy source so valuable in modern industries?

Sometimes called the ‘fourth utility’, you might not automatically think of compressed air when considering energy, but it is vitally essential alongside water, electricity, and natural gas.

What is Compressed Air Used For?

Compressed air is everywhere around us, in car tyres, phone manufacture, roller coaster brakes, buses, and dentistry equipment.

In short, it means that the air has been pressured to a more significant pressure than the surrounding atmosphere.

There isn’t any particular type of air – it’s normal air, made up of 78% nitrogen, 21% oxygen and 1% of other gases, along with natural water vapour.

When that air is compressed, the molecules move tighter together, storing energy.


How is Air Compressed?

While there are many air compressors on the market, the principle remains the same:

  • An air compressor draws in air through an inlet valve.
  • The air is compressed as required through one of several processes.
  • An electric motor often powers those processes.
  • The pressurised air is released into a storage tank through a discharge valve.

Now, in answer to the question, how is air compressed, we’ll need to consider the two different operating systems of an air compressor; positive displacement and dynamic displacement.


Positive Displacement Air Compression

Positive displacement means that the compressor forces the air into a smaller space, thus compressing it mechanically. There are two main types of positive displacement compressor – rotary and reciprocating.

Rotary air compressors have a rotating part that compresses the gas, whereas a reciprocating compressor has a piston cylinder.


Dynamic Displacement Air Compression

Dynamic displacement uses a different process to speed up the velocity of the air, creating energy that builds pressure.

How is Air Compressed Safely?

Air compression is a much safer energy source than many alternatives – such as batteries or steam power.

The safety aspect is an integral part of why air compression is so widely used since it can generate large amounts of pressure without getting dangerously hot.

Batteries are usually less efficient since they are bulky and quickly run out of charge when used in industrial applications.


What Are the Applications of Compressed Air?

Compressed air is used in numerous sectors. For example, it powers pneumatic tools and machinery and assists in manufacturing processes such as food production, where air quality is crucial.

The below table summarises some of the ways we use air compression.


Chemical manufacture: product drying, material handling and air curtains. Quality is vital in chemical production, and compressed air must be clean and dry without oil contaminants to ensure it does not interfere with unstable chemicals.
Automotive – car production, manufacture, air-operated painting. Compressors are used widely in the automotive sector, from assembly lines to finishes.
Industry – construction, mechanics, manufacture. Air compressors are present in various industries, used for mechanical repairs, manufacturing on factories, production lines and road maintenance.
Food and drink – production and packaging. Given the quality risks to food production, compressed air is a common energy source since oil-free compression is free of contaminants.

Air compression is used to create air knives, food filling machines, fluid pumps and packaging.

Pharmaceutical production: laboratories, production and cleaning. As with chemical and food production, pharmaceutical companies must have a clean energy source.

Compressed air is used in product movements, packaging, cleaning and aeration.

What Are the Benefits of Using Compressed Air?

We’ve looked into how is air compressed and where it’s used – but what are the benefits of this alternative energy source?

  • Compressed air is safe and easy to use. It doesn’t contain heat or chemical risks and is free of contaminants.
  • It is energy-efficient. The energy-efficiency credentials of an air compressor will depend on the type of electric motor driving the equipment and whether it’s water-cooled or air-cooled. Still, compressed air itself converts a free source into pressurised energy.
  • Air compression is low cost, both to purchase and to operate. Over the long term, the prices of compressed air are substantially lower than using electricity, steam power, or gas-powered equipment.
  • It is versatile, with a considerable number of applications. From bus brakes to hydraulic drills, you’ll find air compression throughout so many items we see every day.

One of the most significant advantages is that businesses can generate their own compressed air on-site without needing any external utility provision.


Contact AMS Compressors for your air compressor maintenance and air compressor repairs.