Compressed Air Quality

Basics

Different applications require a different compressed air quality - learn why and how to clean your compressed air

Compressed air is inherently dirty, containing contaminants from ambient air and the compression process itself, such as water, oil, and particulates.

These contaminants can damage equipment, reduce efficiency, and in industries like food and pharmaceuticals, lead to product contamination. Understanding and controlling air quality is essential for maintaining operational standards and equipment longevity.

For instance, in manufacturing, the presence of unwanted oil in compressed air can lead to product contamination, equipment damage, and increased maintenance costs. In food and beverage industries, high air quality is crucial to prevent food contamination and meet regulatory health standards. Hence, whatever the sector, ensuring the purity of compressed air is non-negotiable for both operation efficiency and compliance with health and safety standards.

The Main Culprits: Compressed Air Contaminants

The three main contaminants you should be worried about are:

Water
Oil
Particles (dust)

Let's take a look at each of those:

Particles: These are solid impurities that may include dust, rust, or dirt that enters the system through intake or internal erosion of system components. Particles can cause abrasion and wear of pneumatic machinery, leading to frequent maintenance needs and potential downtime.

Water: Moisture is a common contaminant in compressed air systems. It can originate from the humidity in ambient air or from the compression process itself. Excess water can lead to corrosion of metal parts and piping, resulting in leaks and pressure drops. It also poses a risk for microbial growth, which could compromise product purity in sensitive industries like food processing or pharmaceuticals.

Oil: Oil in compressed air typically comes from lubricated compressors and can be problematic, particularly in applications that demand oil-free air such as painting or food production. Oil vapors and aerosols can contaminate end products and lead to the failure of pneumatic controls and valves.

There are some other types of contaminants, like micro organisms, (harmful) gases and odors, but for industrial applications those are of lesser concern

More details about the various contaminants on this page.

Impact on Production

Although it's important, compressed air quality is often neglected or not given enough attention.

The presence of these contaminants in compressed air systems not only compromises product quality but also leads to operational inefficiencies. Unchecked, they can incur high maintenance and operational costs due to:

Increased wear and tear on equipment, necessitating repairs and replacements.
Spoiled or contaminated products resulting in direct losses and potential damage to brand reputation.
Energy inefficiencies as compressors work harder to maintain required pressures, raising utility costs.

High compressed air quality will dramatically reduce maintenance and breakdowns on air tools like grinders and nailers, and reduce wear and tear on machines with air cylinders and moving parts: dirt, water and rust will get stuck inside your pneumatic equipment. Valves will get stuck or wear down, same for cylinders and air tools.

It will also reduce rust and dirt in your compressed air piping system.

Dirty (untreated) compressed air vs cleaned compressed air is like the difference of breathing air on a dusty construction site, or in the middle of a nice forest.

Air Quality Standards

Air quality standards - the guidelines that ensure compressed air is suitable for specific uses are very important in the compressed air industry. The most notable of these standards is ISO 8573-1, which benchmarks the level of purity required in various industrial processes.

ISO 8573-1:2010 is the primary standard for compressed air quality. It outlines precise classifications for air purity, it specifically outlines specific requirements for compressed air purity, quantifying the acceptable amounts of particles, water, and oil in compressed air. \

This detailed classification helps industries determine the level of filtration needed to ensure their air quality meets the necessary criteria for their specific applications.

By categorizing air purity into different classes, ISO 8573-1:2010 allows manufacturers and other users to align their systems with clear, international benchmarks.

More info on the Compressed Air Quality Classes page.

How to Clean Your Air

The right air treatment and filtration process is crucial in meeting the purity standards set by ISO 8573-1

What equipment and strategies do you need to maintain quality compressed air? Managing air quality involves using the right equipment and strategies.

You need to understand how these elements work together to meet purity standards.

Compressed Air Filters

Selecting the appropriate filter for your system's needs begins with understanding the specific ISO class required for your operation. Filters are designed to meet different contamination control levels—each class specifies limits for various contaminants including particles, water, and oil.

Selecting an appropriate filter for your specific ISO class is a key step in creating clean air. There many different types of compressed air filters, each designed to reduce different types of contaminants such as particles, water, oil, and microorganisms

If, for example, your operations require ISO 8573-1 Class 1 quality air, you’ll need filters that can efficiently remove moisture, oil aerosols, and particles down to specified sizes.

Selecting the correct filter is the first step, but maintenance is just as important. Regular checks and replacements are necessary to maintain filter efficiency and air quality.

Read more on the compressed air filters page.

Compressed Air Dryers

Compressed Air Dryers are needed to remove water, moisture, and some oil from compressed air.

Selecting Components

The type of equipment that we need, depends on the air quality level that is required.

A higher level of compressed air quality is more expensive, since it requires more filters, better dryers, more maintenance, etc.

So it's important to meet the quality standards of your machine, but not overdo it.

If you have different machines (compressed air users), with different quality needs, it often pays to clean the compressed air to a basic level for all equipment, and upgrade the air quality level for those user that require it.

Remember, the less stuff you have (dryers, filters, etc), the less can go wrong or break down. Keep it simple.

So if you also need to reach quality class for water and oil, you need to also install the correct dryer and oil filters in addition to the dust filter.

You could buy a standard refrigerated compressed air dryer, or a more expensive desiccant compressed air dryer. If you don't need the very low dew point, why spend the money on an expensive air dryer? Do you need an air dryer at all?

On the other hand, if the air is used as breathing air, of course you need all the dryers and filters (and re-humidifiers)!

How does your compressor fit into all of this?

It doesn't really matter what kind of compressor you have. There are only two types of compressors, as far as air quality is concerned: oil-free compressor and oil-lubricated compressors.

The oil-free compressor is more expensive but doesn't use any oil, so the compressed air produces is completely oil-free.

A more expensive compressor will not give you better air quality. All compressors suffer the same problems with regards to water and dust in the air.

The only exception being oil. Oil-free compressors give oil-free air, and piston compressors tend to ‘spit-out' more oil compared to screw-type compressors.

What compressed air quality do you need?

The quality of compressed air that you need depends on only one thing: the application that you use the compressed air for.

Quality requirements for compressed air vary widely depending on the industry and application. For example, the presence of moisture in compressed air used in metalworking can lead to premature rust and corrosion on finished products. In contrast, in the pharmaceutical sector, even the tiniest contamination by microorganisms or particulates can be catastrophic, leading to severe compliance issues and health risks.

Almost every piece of pneumatic equipment in your factory will have some guidelines about the quality of the compressed air. But of course, use your common sense and decide which factors are important to you.

For example, water in the air is a very common problem, and is probably important for almost all compressed air systems. Oil-free air on the other hand is not a big issue for many people, but is is a big issue for people working in the chemical or food industry as mentioned before.

Bottom line: think for yourself what is important for you. Don't believe the salesman that tries to sell you expensive equipment to get super high quality air, when you don't really need it.

Figure out what is important for YOU.

So, check the manuals of your equipment, it will often tell you what quality of compressed air is needed (like the dewpoint / amount of water and oil that is allowed, are there any special filter requirements?).

A higher level of compressed air quality is more expensive, since it requires more filters, better dryers, more maintenance, etc.

So it's important to meet the quality standards of your machine, but not overdo it.

On the 'clean compressed air' page there's a list of stuff that will determine the quality of your air, plus info how to get rid of it.

Costs and paybacks / pros and cons

In short, this is what I could come up with, in terms of pros and cons of quality compressed air:

Pros of high quality air

Less maintenance of pipe system , easier piping installation (clean, dry air)
Less maintenance of equipment
Less breakdowns, resulting in higher machine uptime

Cons of high-quality air

Cost of equipment like filters and air dryers
Pressure drop over dryer (will result in increased energy consumption)
Pressure drop over filters (will result in increased energy consumption)
Replacement filters costs (filters need to be replaced every once in a while)

It all depends on the application!