What does compressed air contain?

An essential part of your business may be compressed air. Do you know what compressed air contains? We share the compressor secrets with you here.

Estimated Reading Time: 2 minutes

April 24, 2023

The difference between air, oxygen, atmospheric air and compressed air

Air probably seems absurdly complicated right now… Let us simplify it for you. We will start with oxygen. It’s what we use to power our bodies and fires. Oxygen is in air. But it’s only one of many gases. Regular air is about 78% nitrogen, 21% oxygen and just under 1% argon. You’ll also find other gases like carbon dioxide, water vapour and pollutants in the mix. This is what we call atmospheric air. The exact mix will depend on everything from how high up you are to the temperature and factors like the level of industrialisation in your area. 

Atmospheric air is what is drawn into your air compressor. Your air compressor squeezes—or compresses—this air and releases it as compressed air. There is a slight difference between atmospheric air and compressed air though. A lot of the water vapour and other pollutants are likely to be removed from atmospheric air by a system of filters during the compression process. 

Compressed air quality

Although only small amounts of pollutants and water vapour are likely to be present in the compressed air exiting your compressor, these small amounts may cause a big problem. If you’re using compressed air in medicine or the food and drink industry, you’re obviously not going to want to have any polluting particles in there. This is why we have an international system with quality classes for compressed air.

It's possible to improve compressed air quality and remove pollutants and water vapour using drying and filtering methods. The cleaner the air needs to be, the more intensive these methods are. 

Why not just make all compressed air super clean? The more it is filtered, the more energy and costs are involved. You don’t need ultra-clean air to pump tyres on a car. And so, you would use a cheaper, more straightforward air-compression technique that uses less energy and gives you a result that is as good as required. 

Does this impact your choice of air compressor?

If you need Level 0 purity in your compressed air—the very cleanest level—you’ll need a different type of compressor than if you’re permitted to use Level 6 purity.

A Level 0 compressor is most likely going to have a

  • higher price tag,
  • require more maintenance and servicing
  • and have a relatively higher running cost.

It is also going to work differently, with no lubricants injected into the compressor.

And so, yep, purity levels have an impact on your choice of air compressor

But there’s more to think about.

  • The amount of compressed air,
  • the level of compression,
  • the purity.

And a few other factors are going to influence your choice of compressor too.

This might sound complicated, but it’s basically a sign that air compressors are now designed for a large number of specific or niche uses. 

Unsure what you need? No problems. We are always happy to guide and advise you at ALUP. And we will answer any compressed-air questions you might have. It’s what makes the day fun for us. Get in touch today!

Continue through our compressed air guide:
< The Reciprocating Compressor: Oil Lubricated & Oil Free?
Compressed Air Filter: Filtration with Active Carbon & Depth Filtration >

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