Compressed Air Quality and ISO 8573-1 Purity Classes

Airborne particles surround us everywhere.   In a general work environment, nearly four million particles per cubic foot is floating around us at any given time.  When a compressor compresses this air, the concentration increases substantially.  So, compressed air is not only expensive to make, but very dirty.  As the air exits your air compressor and travels into your pneumatic system, there is so much contamination that the International Standard Organization, ISO, created an Air Quality chart with Purity Classes.


This chart is easy to follow and can be found in the ISO8573-1 standard for Air Quality.  It is used to select a cleanliness level for your compressed air system.  The contamination is categorized into three areas; Particles, Water, and Oil (reference above).  A Class is associated with a number for each category ranging from 0 (most stringent) to 9 (most relaxed).  As an example, an Air Quality value of ISO8573-1:2010 [1.2.4] has a Class 1 for Particles, Class 2 for Water, and Class 4 for Oil.  These Class values will show the maximum value in each category.

To define the categories in more detail, I will separate the three to discuss the origins and solutions.

  • Particles: For solid particles, this part comes from many different areas.  The surrounding ambient air that is being drawn into the air compressor is filtered; but the intake filter will only remove large diameter particles.  The smaller diameter particles will go through the filter and into the compressed air system.  Another part is rust particles that occur from steel air pipes and receiver tanks.  Over time, rust will flake off and create particles that can affect pneumatic equipment.  Other particles can come from components inside the air compressor, valves, etc., that wear and breakdown.  In the ISO column for Particles, it is separated into three different micron ranges and concentrations.  The removal of particles from the compressed air is done by traps and compressed air filters.  EXAIR offers two types; Filter Separators with 5-micron filtration and Oil Removal Filters with 0.03-micron filtration.  There are other types of filtration systems depending on your ISO requirement.
  • Water:  Humidity is a natural occurrence as water vapor in the surrounding air.  It can be measured as a dew point temperature.  This is the temperature at which water will condense and make rain.  Inside an air compressor, the air is ‘squeezed”, and the amount of space for water vapor is reduced.  So, it will condense into liquid form as “rain” inside the pipes.  Air that comes out from an air compressor will always be saturated with water.  To remove liquid water, a mechanical device can be used.  Inside a Filter Separator, a centrifugal separator will spin the air and remove the liquid water.  To remove water vapor, a compressed air dryer is required like a refrigerant, desiccant, deliquescent, or membrane type.  Each type will have a dew point range that they can reach.  As an example, a refrigerant type will reduce the dew point near 37 oF (3 oC).  That means that water will not condense until the temperature reaches below 37 oF (3 oC).
  • Oil: This category can be found as a liquid, aerosol or vapor, and it includes more than just oil. It contains small hydrocarbons, CO, CO2, SO2, and NOX.  Oil mainly comes from inside an oil-flooded air compressor.  As the air passes through the compressor, it will pick up remnants of oil aerosols and carry it downstream.  With high temperatures inside the air compressor, some of the oil will vaporize.  Even with oil-less type air compressors, carbon vapor can still be an issue.  Small hydrocarbons can come through the air intake and condense inside the system like water vapor above.  To remove the liquid and aerosol type of oil, Oil Removal Filters can be used.  They are designed to “coalesce” the small particles into larger particles for gravity to remove.  Oil vapor requires an activated carbon to remove.  These types of filter units will adsorb the vapor.  This helps to remove odors as well as dangerous chemical vapors that may be in the compressed air line.

There are a variety of pneumatic systems that use the ISO8573-1 standard.  This will include breathing air operations, food and beverage, pharmaceutical, and the electronic industries.  If you need stringent requirement for your compressed air system, the Air Quality standard should be used by referring to the Class numbers above.  This helps to dictate the types of filtration and air dryers that should be used within your pneumatic system.  If you have any questions about your compressed air system, an Application Engineer at EXAIR can help.

John Ball
Application Engineer
Twitter: @EXAIR_jb


ISO 8573-1 Chart by Compressed Air Best Practice.

Video Blog: Which EXAIR Air Knife Is Right For You?

The following short video explains the differences between the 3 styles of Air Knives offered by EXAIR – The Super, Standard and Full-Flow. All of these Models are IN STOCK, ready to ship, with orders received by 3:00 PM Eastern.

If you need additional assistance choosing your EXAIR Air Knife, please contact an application engineer at 800-903-9247.

Justin Nicholl
Application Engineer



Drying and Cleaning Tubes Using The Standard Air Wipe

A tubing manufacturer called looking for a better way to dry their 3″ (O.D.) tubes after a rinse application. In their current setup, the tubes are being cut by a band saw, which uses flood coolant to keep the blade cool and evacuate chips. After the tubes are cut, they are then bundled together and dipped into a rinse tank to remove the cutting fluid and any machining debris on the surfaces. The tubes are then fed, one by one, through a series of blower driven air knives placed around the outside  of the tubing to dry and clean them before a painting and bar code process. The air knives were working somewhat, but they were seeing some residual streaking on the surface of the tubes that needed to be manually cleaned by hand, slowing down the process.

Example of a typical band saw used for cutting metals and other rigid material.

I recommended the customer use our 4″ Standard Air Wipe in their application. EXAIR Air Wipes provide a 360° uniform, high velocity airflow that adheres to the outside surface, as it passes through the throat of the device. Here is a short video we made showing the cleaning power of our Standard Air Wipes.

The Standard Air Wipe is available in stock sizes from 1/2″ up to 11″. The aluminum construction and PVC hose (included on sizes up to 4″) is suitable for most “general” industrial environments with ambient temperatures reaching as high as 150°F. We also offer Stainless Steel Super Air Wipes, which have the same performance as the Standard, for processes requiring superior corrosion resistance and/or where higher temperatures are possible, up to 800°F.

Super (left) and Standard (right) Air Wipes – ideal for drying, cleaning or cooling round shapes like tubing, hose, pipes, etc.

For help selecting the best product to fit your particular need, please contact an application engineer for assistance.

Justin Nicholl
Application Engineer


FMB FMB Titan Bandsaw Gravity Feed image courtesy of Kitmondo Marketplace via Creative Commons license.

I Just Saved 15% Of My Compressed Air Usage In 15 Minutes

I’ve been pretty entertained over the past few weeks with all the new commercials from a certain insurance company that boasts their ability to save you 15% in 15 minutes.  Well sure enough one of their competitors has now flipped that on them and turned it into almost a joke.  Their competitor now claims to save the same amount in half the amount of time.  While they never say the name it is still making sure that you get the point they are better than their competition.


While the commercials are funny and I do get a kick out them it is still just talk until you actually try them out.   Here at EXAIR we have our own competitors who will claim their flow is one less SCFM than a similar EXAIR product, or maybe 1 dBA quieter.   The fact of the matter is, they can say whatever they want to in advertisements, catalogs, on websites, or even blogs.   What matters is the actual performance of the products as well as the level of service you receive from the company before and after you purchase.  We’ve said it before, and we will say it again, the proof is in the pudding.

EXAIR will not only provide you with enough (if not more than enough) information before you purchase a product, we will also then stand behind the product with a 30 day guarantee.  To top all of that off, we make ourselves available through phone, email, fax, mail, live chat, or even stop in our facility.  The point is we are here to help and we aren’t going to disappear after you buy the product.

Note: Depending upon your current SCFM use and total capacity – you may be able to save 15% by just twisting on some engineered air nozzles in place of open blow offs. This could actually be performed in less than 15 minutes – you get the picture…

Brian Farno
Application Engineer