The Right Filter for a Particular Air Compressor Contaminant

filtersCompressed air systems are unrivalled for powering pneumatic tools, machinery and processes in various industries. But they’re only as good as the quality of the air within their system.

Moisture and particulates can reduce the efficiency of a compressed air system. Contaminants can even make the compressed air system unusable in certain applications. For instance, dirty air can affect food manufacturing or harm employees using it as a source of breathing air and wearing out bearings and seals of pneumatic tools and other equipment in an industrial setting.

This is where proper filters come in. The filters help extend the equipment’s lifespan, lower energy costs and protect employees from contaminants.

But how clean does your compressed air need to be?

Not all applications that use compressed air require the same level of filtration. Some can be supported by a standard dry particulate filter. Others require special types, such as activated carbon filters.

To ensure you get the right filter for your air compressor, (this is different to the topic-should be right filtration for your compressed air line) here are the main contaminants and the filtration types that are best used to eliminate them:


Particulates are small pieces of solid or dry material such as dust, dirt and other debris. Loose metal particles from pipe corrosion are considered particulates as well.

Depending on the application, a compressed air unit with unfiltered particulates can be damaging to the user and end product. It can cause delays in production and even result in costly repairs and quality control issues.

How to filter particulates?

You need dry particulate filters to eliminate solid particles with sizes down to 0.01 micron. Generally a 0.1 prefilter is best practice so that the delicate filter fabric for a 0.01 final filter is not compromised.  But the efficiency of filtration depends whether your filters can do the following processes with precision:

  1. Inertial impaction

This process traps particles that are too heavy to flow with the compressed air stream. It makes separating large particles from the smaller ones much easier.

  1. Interception

The next wall of defence of a good dry particulate filter is its ability to catch smaller particles with diameters larger than the filter media.

  1. Diffusion

Diffusion occurs when the smallest particles move erratically, instead of following the air stream. Since they become independent of the air stream, such particles become easier to intercept and remove from the system.

Vapours and Aerosols

Aerosols consist of small droplets often found within oil-injected compressors. If not filtered properly, aerosols can be harmful to users and products alike.

Vapours, on the other hand, consist of lubricants or any other liquid that is converted to gas. You’ll need special filters to eliminate such vapours from a compressed air system.

How to filter vapours and aerosols?

You have two options to remove aerosols and vapours: coalescing filters and activated carbon filters.

Coalescing filters

The coalescing process involves collecting small droplets of liquid to form large droplets. With a larger size, droplets fall from the coalescing filter into the unit’s moisture trap. Coalescing filters can trap aerosols and dry particulates, but they are not deemed effective in vapour removal.

Activated carbon filters

These filters stimulate the process of vapours bonding with the adsorbent or surface of the filter media, which is activated charcoal. Over time, the oil vapour covers the surface of the activated charcoal and require regular replacement.

Change the adsorbent regularly to remove vapours completely from the compressed air stream. It is recommended to install a dust filter on top of after the activated charcoal filter to ensure microscopic particles won’t enter the air stream if they break out from the bond.

Filtration is crucial to keeping a compressed air-powered production safe and efficient. However, not all air compressor filters are created for the same purpose; make sure to install the type that best suits your application.

If you need help deciding which filter to purchase, don’t hesitate to contact us. We’re here to guide you.