Air Quality Classes – Understanding ISO 8573-1:2010

ISO 8573-1:2010 is the international standard for Air Quality Classes. It lays the ground rules for acceptable levels of pollutants, particulate, moisture, and oil in a compressed air source.

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Specification Example: ISO 8573-1:2010 [2:2:1]

This indicates Class 2 for particles, Class 2 for water, and Class 1 for oil.

Though the standard has detailed standards for maximum particle size, maximum pressure dew point and maximum oil content for different industries and/or environments (see Slide show above) we can generalize a bit and express the levels of air quality like this:

Plant Air – general plant compressed air used for air tools, nozzles etc.
Instrument Air – found in laboratories, paint and powder coat booths, used for climate control.
Process Air – used in food and pharmaceutical applications, electronics applications.
Breathing Air – used for breathing respirators, breathing tanks and hospital air systems.

Achieving the different levels of air quality can be done with 3 basic types of filtration.
     1. Particulate – a filter element removes particles larger than the opening in the filter material. Typically done with particles greater than 1 micron.
     2. Coalescing – use different methods to capture the particles; 1) direct interception – works like a sieve, 2) Inertial impaction – collision with filter media fibers, 3) Diffusion – particles travel in a spiral motion and are captured in the filter media.
     3. Adsorption – the filter element holds the contaminants by molecular adhesion.


The higher the class your air needs to be the more of these filtration methods you will use. Adsorption will remove more and finer particles than a simple particulate filter. And many applications will use a combination of these methods.

EXAIR products, all of which need a source of “clean, dry air” will operate very well utilizing a source of plant air and only a particulate filter. Your process, dictate if you need to supply additional filtration methods for better air quality. For example, an automotive plant using compressed air to blow parts off will not need the kind of filtration a food handling facility will need while blowing a food product off. If you are using a lubricated compressor or have lubricant in your compressed air lines from another source, you will want to use a coalescing oil removal filter.

EXAIR stocks 5 micron particulate filters which are properly sized for each individual product as an option for our customers if they choose. We also stock coalescing oil removal filters for customers who may need to remove oil from the air. Replacement filter elements are also available and should be replaced at least twice a year, depending on the quality of your air.

Oil Removal Filter
EXAIR Oil Removal Filter

Remember to ask about filtration if you have any concerns about your air quality. We can assist in sizing up the proper filters to get the air quality we recommend for proper operation and longevity of our products. 

If you would like to see how we might be able to improve your process or provide a solution for valuable savings, please contact one of our Application Engineers.

Jordan Shouse
Application Engineer
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Images Courtesy of  the Compressed Air Challenge

Cabinets Coolers Do Not Need Instrument Air

I was working with a customer several weeks ago. He did not think he had enough air to make the cabinet cooler work. He filled out a Cabinet Cooler Sizing Guide so EXAIR could assist with determining his heat load and recommend the most efficient model number for the application. His cabinet is 48 inches tall, 36 inches wide and 12 inches deep. The internal temperature inside the cabinet with the electronics running reached 130 degrees Fahrenheit. The ambient temperature was 80 degrees Fahrenheit. The maximum external temperature possible is 115 degrees Fahrenheit. The cabinet was rated for a NEMA 12 enclosure. The NEMA 12 rating is dust and oil resistant , but will not prevent water intrusion.

Cabinet Cooler With Electronic Temperature Control


With all this information, I calculated that my customer needed a model 4325-ETC120 NEMA 12 Cabinet Cooler System with Electronic Thermostat Control. The 4325-ETC120 Cabinet Cooler will use 25 SCFM of compressed air at 100 PSIG. The customer was designing a cooling system for an oil drilling operation. 25 SCFM of compressed air can be difficult for some facilities to generate, but oil wells typically have a compressor capable of putting out enough compressed air to power our products.

After sharing my recommendations with the customer, he was very disappointed that he did not think he would have enough Instrument Air to operate the equipment. The instrument air was tripping us up. Cabinet Coolers require clean, dry compressed air. They do not need instrument air. The cabinet coolers will run on instrument air, but it is not necessary in almost all applications.

Cabinet Cooler
NEMA 12 Cabinet Cooler in a tight installation with 4906 Side Mount Kit

Instrument air or control air is typically a special compressed air system used primarily inside pneumatic control devices or sensitive instruments. In these systems dew point, oil concentrations and particulate filtration are closely monitored to ensure that controls are not damaged. Equipment vendors specify oil concentration limits, and not all instrument air systems share the same parameters. In every facility instrument air is more expensive than shop air or compressed air. You can use instrument air to power cabinet coolers, but it typically is not necessary. On the rare occasions that the vortex tube will be mixed with air that is actually going through a sensor or instrument, instrument air is required. This distinction will have a significant impact on the cost to operate a vortex based cooling system on your electrical enclosures.

My customer was trying to use instrument air, because he believed the standard house air would not work. In many cases standard house air will work, especially when a Automatic Drain Filter Separator, and/or and oil removal filter are used. The Cabinet Coolers feature no moving parts to wear out, but dirty air could block the air flow though the cooler over time so we do recommend a filter on any shop air supply. Instrument air is far more costly to produce than standard shop air. The customer was not interested in providing instrument to cool his cabinet. This is completely understandable. After I explained to him that using filtered compressed air, the cabinet cooler would be more than capable of cooling his troublesome cabinet, he was able to utilize the Cabinet Cooler. The lower operational cost of the shop air over the instrument air was able to make the Cabinet Cooler a great solution.

Dave Woerner
Application Engineer