Compressed air: filter types

Your guide to compressed-air filter types, how they work and why they’re important.

Estimated time to read: 4 minutes

February 23, 2024

Why use compressed-air filters?

It’s early o’clock in the morning. Time to go to work. But first? A cup of happiness. Unfortunately, you’re out of filters. This means your morning coffee is full of grounds and clumps of thick, muddy gunk. Bad news. Especially when you remember how wonderful coffee is when it’s properly filtered. 

And now … Prepare yourself! Because this is where the coffee story starts to relate to your compressed air. You want a certain quality of compressed air to come out of your compressor. You don’t want any impurities in there. Moisture, dirt, oil or, most particularly, thick, muddy gunk, are all going to be bad for your equipment and your compressed-air network. And if you pause to think about how much more beneficial properly filtered compressed air is, you’ll want to make sure you remove these impurities straight away. How? Just like your morning coffee. With filters. Of course, you’ll need the right types of compressed-air filters for the best results.

What types of compressed-air filters are there?

Different types of filters work in different ways. They remove different kinds of nasties and impurities at different stages in the air-compression process. The main compressed-air filter types:

  1. Particulate air filters

  2. Activated carbon air filters

  3. Coalescing air filters

Particulate air filters

Particulate air filters are designed to remove dust, pollen, dirt and other impurities. The better the quality of the filter, the smaller the particulates it blocks. And the quality of the air you need will define the quality of filter you need. All the nasties are trapped on the outer side of the filter, with only air of an acceptable quality passing through into your compressed-air network. 

Particulate air filters are most frequently used after an adsorption dryer. If you find there’s still too much moisture in your air after it’s passed through the particulate filter, you may want to look at a coalescing filter. And if you want a finer filter to remove fumes and vapours, an activated carbon filter should do the trick.

Activated carbon air filters

Without any doubt, activated carbon air filters have a cooler name than anything else on this list. They’re also known as vapour removal filters. Admittedly this name tells you a little bit more about what they do: remove vapours. In fact, the activated carbon in the filter attracts and draws vapours to the filter. This means any kind of gaseous contaminants like chemical fumes and chemical vapours—even odours and smells—are filtered out. 

The filter has a large surface area, giving the activated carbon a much larger opportunity to work its magic. Of course, as the filter becomes more saturated or clogged with the vapours it has filtered out of the air, it will need to be replaced. Otherwise, the pressure will drop. And, of course, you don’t want that.

Activated carbon filters are mostly used in the food-processing industry and other places that require the production of pure, clean, breathable air. The filters are very easy to maintain. And, in fact, they’re often combined with one of the particulate filters you’ve just read about. This offers extra protection in case any of the carbon particles break off the filter and escape into the air.

Of course, there are times when there are better options than activated carbon filters. If you need to remove moisture from your air, you’re best using a coalescing air filter.

Coalescing air filters

Coalescing air filters are designed to remove liquids and moisture. This makes them sound like air dryers. They’re different, and in fact, they work best when operating in conjunction with an air dryer. Install your coalescing air filter a little further down the line from your air dryer so that the majority of the moisture has been removed. Otherwise, your coalescing air filter will become saturated very quickly. A coalescing filter is best dealing with water, lubricants and other oils when they’re travelling as tiny little particles in an aerosol form. The coalescing air filter basically opens up pathways that force the tiny particles to collide with each other and form larger particles that are more easily caught and filtered out. It's worth noting that coalescing air filters will catch other particulates, like dust, pollen and dirt, that a particulate filter would also catch. This means that coalescing air filters score big points for versatility. However, they don’t rate quite as well for energy efficiency. They need to be replaced fairly regularly to avoid pressure drop.

What compressed-air filter type do you need?

The first step to identifying what compressed-air filter type you need is to find out the quality of compressed air you need. If you’re inflating the tyres of trucks in a quarry, you won’t need the same air quality as a dentist or a company manufacturing medicines. The quality of air you need will define the type of compressed-air filters you need in your compressed-air network.

Of course, it is possible to filter the air to an incredibly fine degree in any situation. But this will cost you a lot of money. And the tyres on the dump trucks aren’t too worried if you pump a few nasties in. 

You’ll also want to factor in the long-term costs. There are compressed-air systems with a relatively small price tag when they’re sitting on the shelf. However, the cost of operations, repairs and new materials will add up over time. If you’re just looking at an air compressor for occasional use, this won’t be a problem. If you’re going to be using it continuously, you’ll want to do a bit of extra homework.

Questions? Advice? Help?

Do you have questions about compressed-air filters? Types of filters? Or do you just want the advice from experts? No problem. The only thing we enjoy more than discussing air filters is helping customers. Get in touch with us today!

Scroll Up ↰

See also