Contaminants that affect compressed-air systems

Learn about the causes of contamination in air-compressor system and tips on how to avoid compressed-air contamination.

Estimated time to read: 3 mins

January 18, 2024

Is your compressed-air system contaminated?

We all know how important the quality of compressed air is. You need to achieve a certain level of quality to use your compressed air for some applications. And achieving different levels of compressed-air quality is only possible with the right systems. 

Unfortunately, regardless of the quality you need and the system you use, a compressed-air network is open to all kinds of contaminants. There are four main sources of contamination: 

  1. Atmospheric air drawn in by your air compressor

  2. The air compressor itself

  3. The air receiver in your system

  4. Distribution piping.   

With filters, cleaning and regular maintenance, you’re able to minimise the chance of your compressed air becoming contaminated. But fail to do it and you risk all kinds of problems.

Compressed-air contamination from water

Would you believe it? About 99.9% of all the contaminations in compressed-air systems are caused by water. It covertly infiltrates your system under the cover of atmospheric air and doesn’t take long to start causing problems. Whether it’s in the form of vapour or condensation, water is horribly destructive. It will give you all kinds of problems ranging from corrosion and reduced tool performance to increased maintenance costs, greater air leakage, problems in control systems and instruments, and of course, plenty of potential for growing mould and bacteria you would probably prefer to go without. How do you avoid this? Regular maintenance, including the replacement of your filters and regular draining of your air dryer.

Compressed-air contamination from oil

Here’s the problem: it’s never particularly pleasant to have water in your air-compressor system. But oil? You actually do want that in your system. You just want to avoid the compressed-air contamination it might lead to.

As with water, there are traces of oil in the atmospheric air drawn in by your compressor. The oil will form a vapour or aerosol in your compressed air, or condense it back into a liquid state. It will even mix with water to form an acidic condensate. This will damage different parts of your compressed-air system, affect production equipment and of course, contaminate your compressed air. This is why oil-lubricated air compressors are not permitted for a lot of food and medical applications. 

What’s the best way to avoid compressed-air contamination from oil? Regular maintenance. We generally wouldn’t recommend switching to a non-oil-lubricated system unless you need very-high-quality compressed air or a particularly low oil content. And there’s a reason for this. First of all, the cost of a non-oil-lubricated system is much higher. And it actually requires even more maintenance than a standard system. If you’re struggling with the maintenance schedule now, a more demanding system is not the way to go.

Compressed-air contamination from dirt, dust, and other particles

How large do you think a typical dirt or dust particle is? If you think it’s big, you’re in luck; anything larger than two microns will typically be picked up by your different air filters. It’s what they’re there for. Your air filters stop all these devious particles from sneaking into your compressor and making their way through your compressed-air network and into your products. 

The only problem is the other little dirt and dust particles. The tiny ones that are less than two microns in size. When they’re that small, there’s a good chance they’ll find their way through the filters. They’ll eventually bump into each other, merge into bigger particles and create more drastic blockages in your system. These blockages have the potential to affect the functioning of your tools, cause damage and create even more opportunities for water and oil to congregate. Once in the system, particles like to sneak into your products too. Depending on what you’re working on or producing, you’ll probably end up with a huge headache. 

The solution? Fresh filters. Regular maintenance and cleaning of your air compressor, especially around the air-inlet valve. If your compressor is outside, you might consider building walls around it. If it’s inside? You might have to move your ventilation to a place where it’s exposed to less dirt and dust. 


Remember all the water vapour and condensation from earlier? It likes nothing more than to create rust. And rust likes to spread. It will sneak under the coating on the inside of your pipes and do its best to make that coating flake off and cause chaos elsewhere in your compressed-air network. All the more reason to use the right filters, clean and replace them frequently, and regularly check for signs of rust in your compressed-air network. If you find some, be prepared to eventually replace whichever part of the network you’ve found it in.

Advice, questions and help

One of the most common questions to ask when it comes to compressed-air contamination is ‘How bad is it?’ This will depend on how you use your air compressor and compressed-air network. A little rust here or there may not be an immediate problem in a garage. A touch of dust and dirt is understandable if you’re based on the beach or in the desert and prepared to clean things more frequently. And a little oil is not usually enough to substantiate full-fledged panic… The degree of problems you’ll face due to compressed-air contamination depends on what you use your system for.


Want more information about your specific contamination situation? Please, get in touch with us. We will gladly discuss your situation with you, offer you advice and any other form of assistance. Give us a call today!

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