How do I choose an air filter for my compressor?

I’ve found (the hard way) that it’s much better to dry the air all you can BEFORE it is stored in the tank. I live by the beach, and humidity was often a problem. Without an inline dryer my paint guns would always sputter and the plasma cutter had issues. My compressor before modifying would get LOTS of water into the tank which isnt good for either the tank or your tools, and a separator after the regulator didn’t stop moisture in the lines. I drained a much higher volume of water from the tank than from the separator.

What fixed it was to mount a four pass oil cooler after the compressor but before the tank. The lower line of the cooler goes to the inlet of a filter/separator which captures the water before the air goes into the tank. I now get next to zero water from the tank drain, but have to keep up with the filter drain.
Behind the cooler is a pair of large flat 120V “muffin” fans which run when the compressor is on.
I still keep the Motorguard M26 filter at the plasma cutter, but now the elements seem to last forever.

Choosing the best compressed air filter for your business depends on your application, and several key factors. But first, let’s start with talking about the importance of a high-quality filter.

The air within your compressed air system isn’t naturally clean. In fact, it likely has many of the same particles, aerosols, and vapors that may be found in the natural environment. Metal particles from the piping may often be found in the air. Filters are critical in improving the air quality within your system, no matter the application.

What Does A Compressed Air Filter Do?

The answer to this question is relatively straightforward. The compressed air filter is simply there to remove particles or contaminants from the compressed air. Some examples of contaminants and particles that can be removed include:

• Aerosols
• Particulates
• Vapors
• Dust
• Dirt
• Metal particles (from pipe corrosion)
• Pollen

The best compressed air filter for your business will remove the particles and contaminants found within the air. It’s important to understand the different types of filters to make the best decision possible for your business.

The International Organization for Standardization can help you to understand the different contaminants and purity classes.

Types Of Compressed Air Filters

Coalescing Filters – These filters are effective in removing water, oil, and aerosols. They also prevent the re-entering of any trapped contaminants. Coalescing filters can reduce particulate levels down to 0.1 micron in size, and liquids down to 0.01 ppm.

Vapor Removal Filters – These filters operate through adsorption, or holding a gas, liquid or solute as a thin film. They are especially effective at removing lubricant aerosols by using various types of carbon to catch or remove gaseous lubricants that could make their way through a coalescing filter.

Dry Particulate Filters – These are used to remove desiccant particles after they go through an adsorption dryer. They operate in a similar manner to a coalescing filter.

What Filter Do I Need For My Air Compressor?

To select the right type of air filter, you need to understand your compressed air application. Pharmaceutical applications often require a higher quality of compressed air than a typical manufacturing facility, for example.

It’s important to understand whether some oil in the compressed air will compromise your process. Installing a coalescing filter limits the presence of oil in the compressed air. Low energy usage may be another factor. Finding a high-efficiency filter will create a clean air environment while avoiding the likelihood of a large pressure drop.

There are several more elements to consider before selecting an air filter for your business.

• Particle size – Standard air filters may remove particles from 5 to 40 microns. If you’re looking to remove the smallest of particles, there are also specialized filters to remove particles less than 1 micron in size. This is ideal for the pharmaceutical and food industries, where cleaner air is a must.
• Pressure drop – The air filter you select will impact how flow is managed. It’s important to consider the maximum head loss for the filter. You can do this by referring to pressure drop curves, according to the flow rate that the manufacturer provided. You’ll want to avoid a pressure drop larger than 5 PSI.
• Operating temperature – There are high performance filters available on the market for air compressors that operate at over 450 degrees Celsius.
• Environment – Compressed air filters are covered under the ISO 8573 standard, which discusses the purity classes of compressed air. The presence of solid particles, or oil and water anywhere in the compressed air system (including the filter) are covered. The standard also covers general information about pollutants, including gaseous and microbiological pollutants.

How To Know When You Need A New Air Filter

This depends on factors like the amount of usage your air compressor has undergone, as well as the quality of the air that you’ll need for your application. If your air compressor is experiencing pressure drops, it may also be a filter issue.

Below are a few more indicators that may be indicators you need to replace the filter:

• If the manufacturer will no longer service the existing filter
• If an air audit reveals that you are operating with low-quality air
• Pressure drops continue to plague your compressed air system and your business

Your preventative maintenance team will be able to let you know when it’s time to invest in a new filter.

If you are experiencing any of the above issues it may be time to replace the air filter. If you have any questions about the type of air filter that you need for your business, contact one of our experienced sales representatives today!