Why does my air compressor need a filter?

Why does my air compressor need a filter?

It may not be immediately obvious, but each cubic foot of compressed air can contain millions of dirt particles, water and oil. This contamination of the air is most noticeable when you are using your compressor for something which demands a fine finish – paint spraying, for example. Unfiltered (or when your filter isn’t performing as it should) you’ll notice the spray finish has a dappled appearance, caused by dirt and water in the air flow. Filter such particles out, and you’ll find the finish improves enormously.

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But filtering isn’t only required where the application demands a fine finish. Particles in the air can cause additional wear on the compressor and your air tools. They can coat valves and other parts of the machine. They use more energy and cost more to run (because the motor has to work harder to force the air around the system). And they increase the likelihood of a breakdown and/or the frequency of servicing.

Filtering solid particles

We have spoken about separating oil and water from your compressed air system previously, so in this piece we shall focus on filtering solids (although a filter may also remove some oil and condensate).

     Particulate (or coarse) filters scrub the air of contaminants measuring 5 to 40 microns
     Fine and micro filters remove particles smaller than 1 micron
     Activated carbon filters capture oil vapours
     Sterile filters scrub the air of germs and would typically be used in pharmaceutical, medical, food or beverage applications

As you might expect, the tiering of filters is important. Place a micro filter upstream of a coarse filter and it will immediately become clogged, restricting air flow and reducing the effectiveness of the compressor. Instead, the coarse filter should come first in the air stream, collecting the larger particles before enabling the micro and other filters to do their jobs.

Maintaining the filter

Like the filter in your coffee machine or vacuum cleaner, as particles gather, so the machine performs less effectively. It’s important, therefore, to replace filters periodically. Precisely how often the filter will need replacing depends on the compressor, the filter and the application. You compressor may be fitted with a sensor which may monitor air flow at the filter and alert you when pressure starts to drop due to clogging.

Our maintenance service contracts ensure filters are replaced before they become clogged enough to reduce performance, or impact energy costs and compressor wear. To talk to us about keeping your air compressor equipment in prime condition, please call us on 0114 243 2347, or contact us.

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