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.

ISO8573-1-2010

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
Email: johnball@exair.com
Twitter: @EXAIR_jb

 

ISO 8573-1 Chart by Compressed Air Best Practice.

Common Compressed Air Symbols

When any product / system is designed drawings are made to assist in the production of the designed product. For example if a mechanical part is being machined you may see symbols like these to verify the part is made correctly:

GD&T
GD&T Symbol Examples

Same with an electrical panel, they use symbols like the ones below to note the type of equipment used in a location.

electronic.JPG
Electrical Symbol Examples

 

Then there’s the Piping & Instrumentation Diagram (P&ID)…it depicts an overall view of a system, showing the flow (usually fluid or electricity) through that system’s components, giving the viewer an understanding of the operation, and expected results from said operation.

Some examples of symbols you might find in a compressed air system are:

Compressors:

all-compressor
The one on the left can be used for any air compressor. The others denote specific types of air compressor (from left:) Centrifugal, Diaphragm, Piston, Rotary, and Screw.

 

Air preparation & handling:

filters-and-regulator-symbols-and-pic.jpg
The symbols on the left denote the EXAIR products on the right: Automatic Drain Filter Separator, Oil Removal Filter, and Pressure Regulator

Instrumentation and control:

instrumentation-and-controls1.jpg
The symbols on top denote the EXAIR products below (left to right): Flowmeter, Pressure Gauge, and Solenoid Valve

Occasionally, we’re asked if there are standard ANSI or ISO symbols for any of our  engineered Intelligent Compressed Air Products…and there aren’t.  Perhaps one day they might make the cut, but for now, their standard convention is to choose a shape and call it out by name.  It might look something like this:

sak-pid1
From top left, and then down: Automatic Drain Filter Separator, Oil Removal Filter, Pressure Regulator, and Super Air Knife

If you have questions about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Jordan Shouse
Application Engineer
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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.

Filters
EXAIR FILTER SEPARATORS

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

Comparing the Different Styles of Compressed Air Filters

Most of EXAIR’s line of Intelligent Compressed Air Products have no moving parts and require no maintenance. The caveat to the “no maintenance” aspect is proper filtration at the point of use. Many products have very tight orifices that could get clogged from any contaminants such as particulate, condensate, and lubricant. EXAIR recommends point of use filtration to be installed just upstream of any EXAIR Product for this purpose.

There are three primary types of compressed air filters: particulate, coalescing, and adsorption. Each have their own inherent characteristics and can be used in conjunction with one another. Each style is used to handle a different form of contaminant that’s present within the distribution system of your compressed air supply.

9001
EXAIR Model 9001 Auto-Drain Filter

Particulate filters – Particulate filters are available with different filtering mechanisms that allow you to control the particulate size that will be filtered out. The higher the level of filtration, the greater the pressure drop you’ll experience at the outlet of the filter. Styles are also available with either a polycarbonate bowl or metal bowls, depending on the application and environment.

Any filter with a polycarbonate bowl should have a metal guard on the outside to provide protection for personnel should a failure occur. In these styles of filters, compressed air is forced through a filter element that blocks any particulate contained within the air supply.

These filter elements are generally a sintered bronze material with filtration levels from 40-5 micron possible. Over time, the filter elements can clog and increase the pressure drop at the discharge of the filter. They’re relatively inexpensive and should be replaced yearly to maintain optimum performance and mitigate pressure drop. They also remove liquid drops as well from the air supply, containing them within the bowl. Styles with both manual-drains and automatic-drains are available that will drain the bowl of excess moisture automatically through the bottom of the filter.

9005
EXAIR Model 9005 Oil Removal Filter

Coalescing Filters – The coalescing filter is used to remove very fine water vapor as well as any residual oil. These filters are highly recommended to be installed just prior to any dryer that contains a media that would be compromised by any lubricant passing through it. Coalescing filters utilize an element typically made up of glass fibers that “coalesce”, or combine, the fine water vapor and oil aerosols until the droplet size becomes large enough that it drops off into the bowl or filter housing. With a coalescing filter, the most common cause of pressure drop increase is due to particulate clogging the filter element. Because of this, a particulate filter should always be installed just prior to any coalescing filters.

Adsorption Filters – The final type of compressed air filter is the adsorption filter. Where the particulate filters can remove the majority of contaminants and the coalescing filters the residual oil, they are not capable of removing lubricant vapors or oil. That’s where the adsorption filter comes in. In addition to removing the finest oil vapors, they also can eliminate odors from the compressed air supply. The oil vapors and odors adhere to activated carbon within the filter, removing them from the air supply. These filters are commonly found within the food processing industry, where any contaminants in the air supply could impact the integrity of the product.

EXAIR has a line of Automatic Drain Filter Separators and Oil Removal Filters, available from stock, to make sure the quality of your air supply is sufficient for proper operation of any EXAIR product. Feel free to give us a call and any of our Application Engineers will be happy to assist you.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

The Importance of Compressed Air Filtration

In this blog, I would like to turn your attention to our accessories that support our Intelligent Compressed Air® Products; the Filter Separator and the Oil Removing Filter.  EXAIR products use compressed air to coat, conserve, cool, convey and clean.  So, to keep our products running properly and efficiently, we need to supply them with clean, pressurized air.  If we look at the two types of filters that we offer, we can see how they can play an important part in your compressed air system.

Filter Separators

Filter separators are used to remove bulk liquid and contamination from the compressed air stream.  They have a 5-micron filter and work very well if you get a slug of liquid in your compressed air system.  They use mechanical separation to remove the large particles of dirt and water from the air stream.

Most facilities use some type of compressed air dryer in their system to dry and condition the compressed air.  But, if a system failure occurs, then water, oil, and dirt can be pushed into the compressed air lines and perhaps into your EXAIR products.

Even if you have good quality air, it is still important to keep your products protected.  I would consider the Filter Separator as a minimum level of protection that should be used.

Oil Removal Filters

The Oil Removal Filters are used to keep the compressed air even cleaner yet.  They work great at removing very small particles of dirt and oil.  The 0.03-micron media of the Oil Removal Filter is designed to “coalesce” the fine liquid particles into large droplets.

Thus, allowing gravity to remove it from the compressed air stream.  Some common issues allow for dirt and oil particles to collect in “dead” zones within the air lines.  As it piles up and grows, portions can break off and get into the air stream affecting pneumatic devices.

The Oil Removal Filter will be able to help eliminate this long-term problem in your compressed air system.  As a note, Oil Removal Filters are not great for bulk separation.  If you have a system with lots of water, you should use a Filter Separator in front of the Oil Removal Filter to optimize the filtration.

Now that we went through each type, how do we use them together to get the best supply of compressed air?  We always want them to be installed upstream of a Regulator.  This is because the velocity is lower at higher pressures.

Lower velocities mean lower pressure drops which is great for supplying the proper amount of compressed air to EXAIR products.  If you are using a combination of both filters, the Filter Separator will be upstream of the Oil Removal Filter.  The Filter Separator will knock down the large particles and liquid slugs allowing the Oil Removal Filter to remove the smaller droplets and particles.

EXAIR offers a range of sizes to help support our products.  They range from ¼” NPT ports up to 1 ½” NPT ports.  The size of the ports determines the flow rating for each unit.  EXAIR also has Mounting Brackets to mount the filters to walls or frames.

To support each type of filter, we have replacement elements and bowl kits.  Since the function of the filter is to remove debris, we recommend to change the filter element once a year or when it reaches 10 PSID pressure drop; whichever comes first.

If we can analyze the compressed air systems, I would like to categorize it into a good and premium quality.  For the good quality of compressed air, you can have the compressed air run through the Filter Separator.  For the premium quality of compressed air, you can have your compressed air run through the Filter Separator and then through the Oil Removal Filter.

With clean quality air, your EXAIR products will provide you with effective, long-lasting performance without maintenance downtime.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

What’s The Big Deal About Clean Air?

Compressed air isn’t called manufacturing’s “Fourth Utility” (the first three being electricity, water, and natural gas) for nothing. Pneumatic tools are popular because they’re often so much lighter than their electric counterparts. Compressed air can be stored in receiver tanks for use when other power supplies are unavailable or not feasible. Many compressed air operated products can be made to withstand environmental factors (high/low temperature, corrosive elements, atmospheric dust, oil, other contaminants, etc.,) that would make electric devices very expensive, unwieldy, or impractical.

One of the most valuable considerations, though, is that your compressed air system is, by and large, under your control.  The type and capacity of your air compressor can be determined by your specific operational needs.  The header pressure in your supply lines is based on the applications that your air-operated devices are used for.  And the performance & lifespan of every single component in your compressed air system is determined by the care you take in maintaining it.

I covered the importance of compressed air system maintenance in a blog a while back…today, I want to focus on clean air.  And, like the title (hopefully) makes you think, it’s a REALLY big deal.  Consider the effects of the following:

Debris: solid particulates can enter your air system through the compressor intake, during maintenance, or if lines are undone and remade.  If you have moisture in your air (more on that in a minute,) that can promote corrosion inside your pipes, and rust can flake off in there.  Almost all of your air operated products have moving parts, tight passages, or both…debris is just plain bad for them.  And if you use air for blow off (cleaning, drying, etc.,) keep in mind that anything in your compressed air system will almost certainly get on your product.

Your compressed air system may be equipped with a main filter at the compressor discharge.  This is fine, but since there is indeed potential for downstream ingress (as mentioned above,) point-of-use filtration is good engineering practice.  EXAIR recommends particulate filtration to 5 microns for most of our products.

Water: moisture is almost always a product of condensation, but it can also be introduced through faulty maintenance, or by failure of the compressor’s drying or cooling systems.  Any way it happens, it’s also easy to combat with point-of-use filtration.

EXAIR includes an Automatic Drain Filter Separator in our product kits to address both of these concerns.  A particulate filter element traps solids, and a centrifugal element “spins” any moisture out, collecting it in the bowl, which is periodically drained (automatically, as the name implies) by a float.

Point of use filtration is key to the performance of your compressed air products, and their effectiveness. Regardless of your application, EXAIR has Filter Separators to meet most any need.

Oil: many pneumatic tools require oil for proper operation, so, instead of removing it, there’s going to be a dedicated lubricator, putting oil in the air on purpose.  Optimally, this will be as close to the tool as possible, because not all of your compressed air loads need oil…especially your blow offs.  If, however, a blow off device is installed downstream of a lubricator (perhaps due to convenience or necessity,) you’ll want to do something about that oil. Remember, anything in your system will get blown onto your product.

If this is the case, or you just want to have the cleanest air possible (keep in mind there is no downside to that,) consider an EXAIR Oil Removal Filter.  They come in a range of capacities, up to 310 SCFM (8,773 SLPM,) and the coalescing element also offers additional particulate filtration to 0.03 microns.

In closing, here’s a video that shows you, up close and personal, the difference that proper filtration can make:

If you’d like to discuss or debate (spoiler alert: I’ll win) the importance of clean air, and how EXAIR can help, give me a call.

Russ Bowman
Application Engineer
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Oil Removal Filters – Keeping Compressed Air Clean

Compressed air filters help to keep the air clean and condensate free to protect equipment from dust, dirt, pipe scale, oil and water. Even though the compressed air system will typically have a main dryer, additional treatment is often necessary. For this discussion, we will focus on the oil removal process and filter type.

After the compressed air has passed through a particulate filter, the dirt, dust and water droplets have been removed.  Oil that is present is much smaller in size, and mostly passes though the particulate filter.  The installation of a coalescing filter will provide for the removal of the majority of the fine oil aerosols that remain. The coalescing filter works differently than the particulate filters. The compressed air flows from inside to outside through the coalescing filter media. The term ‘coalesce’ means to ‘come together’ or ‘form one mass.’  The process of coalescing filtration is a continuous process where the small aerosols of oil come in contact with fibers of the filter media. As other aerosols are collected, they will join up and ‘come together’ and grow to become an oil droplet, on the downstream or outside surface of the media.  Gravity will then cause the droplet to drain away and fall off the filter element.

9005
Example of a 0.03 Micron Coalescing Oil Removal Filter

Some important information to keep in mind –

  • Change the filter regularly, not just when the differential pressures exceeds recommended limits, typically 5 PSI
  • Coalescing filters will remove solids too, at a higher capture rate due to the fine level of filtration, using a pre-filter for solids will extend the life
  • Oil free compressors do not provide oil free air, as the atmospheric air drawn in for compression contains oil vapors that will cool and condense in the compressed air system.

If you would like to talk about oil removal filters or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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