In-Line Filtration for Compressed Air

Inline filters for compressed air are rated by the size of particulate they are able to remove. The smaller the micron rating, the smaller the pore size and the smaller the particles it is able to capture and remove from the airstream. 

• A 1 micron filter can remove particles down to a size of 1 micron. These filters can capture most allergens, mold spores, larger dust particles and many bacteria. 
• A 0.01 micron filter removes material 100 times smaller than a 1 micron filter can capture. Fine particulates from combustion engines, suspended atmospheric dust and many viruses fall into this size range. 

Most 1 and .01 micron elements are coalescing-type filter elements, which remove aerosolized oil mists as well as dry particulate. Most filter companies sell the 1 micron and the .01 micron elements at the same price. So which inline filter is right for you? It depends on your applications and how clean you need the air to be. 

• Most plants can be served well by 1 micron filters. These inline filters are perfectly adequate for removing the majority of dry particulate and oil from compressed air. They will tend to have a longer life than 0.01 micron filters, but have higher oil carryover and will not remove the smallest dry particulates. 
• A 0.01 micron element will take out more oil and smaller particles, such as the fine particulate created by combustion engines. These filters will produce drier, cleaner compressed air, which can be important for sensitive applications. The only drawback is that it will have a shorter life and experience higher pressure drop because it is collecting more oil and particulate. 

The literature for the inline filter will provide specifications, including the micron rating and the percentage of particulate it removes of this size. For example, the PneuTech Utility Grade Coalescing Filter removes 99.99% of particulate down to 1 micron, while the PneuTech High-Efficiency Coalescing removes 99.99% of particulate down to 0.01 micron. 

Not sure which inline compressed air filter is right for you? Contact us for help in designing your compressed air filtration system.

Inline filters should be replaced at least annually or after 8,000 hours of operation. Filters may need to be changed more frequently if the incoming air is dirty or oily. The inline filter for your compressed air system removes oil and particulates from the compressed air supply. Over time, the filter media becomes loaded. When this happens, you will notice increased pressure drop across the filters, which is shown by the pressure differential indicator. Change the filters when indicated by the pressure differential indicator, even if it has not yet been a year.

When inline filters are loaded, they can no longer perform their job of removing contaminants from compressed air. This results in poorer air quality. Operating with loaded filters also drives up energy costs, as it takes more energy to push compressed air through the saturated filters. You will need to change inline filters more often if: 

• Incoming air contains a lot of particulates.
• You experience high oil carryover from your air compressor.
• The filtration system has not been adequately sized for your compressed air system.

Do compressed air filters need to be changed annually, even if you are not noticing pressure drop? Yes. Pressure differential indicators can give false readings sometimes due to improper installation of the filter element or a small hole in the element. In this case, no pressure differential is present. However, the filter media will still be saturated and worn. For best results, make sure your inline compressed air filters are changed every year.