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Air Line Filter Buyer's Guide

Jan. 29, 2024

Air Line Filter Buyer's Guide

How to Pick the Perfect Air Line Filter

By Melissa C.

Air Compressor Expert

Air line filters extend the life of your compressor and improve the quality of air being put out.

Aside from filtering out additional moisture from the air, air line filters remove particulates such as dust and dirt.

While most users only need general purpose filters, high-efficiency filters may be needed for medical applications or to protect delicate instruments from contaminants.

For different applications, there are some different options to choose from.



General Purpose Filters

General-purpose air filters are ideal for basic water, oil, and dirt removal. They keep the air moderately clean and extend the life of your air compressor.

Average general-purpose filter elements can catch particulates 5 microns in size. However, some general-purpose filters can catch particulates as small as 1 micron.


Activated Carbon Filters

Activated carbon typically comes from charcoal and highly porous biochar. These air line filters are commonly used in OSHA-regulated breathable air systems.

They offer the largest surface area and lowest pressure drop, meaning more adsorption and less interruption. A major benefit to activated carbon filters is that they remove oil vapors and odor.


High-Efficiency Filters

These in-line filters are great if you're looking to conserve energy and filter particulates as small as 0.01 microns. High-efficiency air line filters are ideal for painting applications to eliminate the concern of "fish-eye" flaws in paint finishes.

High-efficiency air line filters are designed to filter more water, oil, and contaminants than other filters while still reducing pressure drop.


Water Separator Filters

These air line filters are generally used when the main contaminant in your air is water. However, many of them are also able to filter out dirt and oil.

In addition to trapping water at the bottom of the filter bowl, water separator filters also reverse air-flow direction 180-degrees inside the filter and pass it through a stainless steel mesh element.

By Melissa C.

Air Compressor Expert

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In-Line Models

If you need clean air for painting, polishing, or food production uses, you'll need at least one in-line filter in addition to any intake coverage. In-line filters are installed between the compressor and the air lines, as the name suggests, to capture contaminants that developed in the tank or that made it past the intake filter.

Coalescing Designs

When oil or water is sprayed into a fine mist by machinery or exhaust ports, the tiny droplets that form the mist are known as aerosols. Removing aerosols from compressed air is tricky and requires more than just your basic filter. Coalescing compressor filters trap even the smallest particles of both liquids and solids by combining multiple layers of very fine mesh.

As the largest of the particles or droplets first catch on the filter fibers, they attract smaller and smaller contaminants to them as well. Coalescing designs combine three different filtering actions in one filter to catch as many solid and liquid contaminants as possible.

These kinds of filters are usually required for food and medical manufacturing, but they're also recommended for better results with paint spraying as well. They work best when used in conjunction with a particulate pre-filter that traps larger materials to keep them from filling up the gaps in the filter material too rapidly.

Particulate Filters

While coalescing filters can remove solid particles, they're not specifically designed for solids. Particulate filters include permeable membranes that stop solid contaminants while letting air flow through with little to no reduction in pressure. However, they're relatively poor at catching the finest solid particles and all but the largest droplets of liquids.

These filters are often used as the primary in-line filter for applications that need clean air but which can handle a small amount of fine dust or moisture. For more demanding applications, they're used as a pre-filter for coalescing designs.

Vapor Traps

For food and medication production, even unpleasant odors and completely gaseous vapors can result in quality or safety issues. Vapor canisters that contain activated charcoal can remove gasses and vapors from the air supply coming out of the compressor, but they won't do much about solid or liquid particles. Only the most demanding air compressor applications generally require vapor filters.

Looking for filters to fit your particular air compressor? We here at Compressed Air Systems are ready to help you find any accessories you might need for your compressed air equipment. Call us today.

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