Our Guide to Compressed Air Filters


Why are they needed? Air leaving any air compressor will be high in water content, as well as a concentration of oil and other contaminants. Unfiltered compressed air may contain dust, oil, rust, moisture and other harmful substances, and therefore requires filtration.

What are they used for? Often referred to as line filters, compressed air filters are used to remove contaminates from compressed air after compression has taken place. There are many types, sizes and quality of filters, suitable for all applications. They can be used in conjunction with a compressed air dryer if clean dry air is required.

How do they work? In the first stage of filtration, the compressed air passes through a mesh filter, which creates a coalescence effect. Here bigger particles are absorbed on the filter and the water will condense into larger droplets, which can then pass into the separation chamber.

The compressed air is slowed down, which makes the particles condense on a honeycomb-like pad, allowing the water droplets to travel to the bottom of the drainage system and through an automatic or electric drain valve to the discharge.

In the first filtration stage the majority of water droplets, oil and large particles are removed. In the second filtration stage the air is passed through fibre, generating thousands of small vortices and accelerating the air.

What are particulate filters?

Also known as pre-filters, particulate compressed air filters are used to remove dust and particles from the air down to 1.0 µm and liquid water and oil down to 0.1 µm.

What are coalescing filters?

Also known as after-filters, coalescing filters remove water and oil aerosols, which coalesce the aerosols into droplets. This happens partially because of a torturous path through the element and pressure drop.

Coalescing filters remove both water and oil aerosols from the air stream and are rated at particulate contamination through direct interception. Filtration of oil, water aerosols, dust and dirt particles to 0.01 µm is the best achievable in industry.

What are activated carbon filters?

Activated carbon filters utilize a composite carbon material to remove oil vapours and hydrocarbon odors from the air. They are used in factories where food is produced or for breathing air.

If you are unsure of the correct filtration for your application contact PPS to discuss your needs. If needed we will visit you to determine the correct filters for your application.