Inline Filter Selection for Compressed Air Systems

18 Aug.,2025

 

Inline Filter Selection for Compressed Air Systems

Inline compressed air filters are vital for having clean air for your applications and pneumatic tools. However, it can be difficult when trying to decide. Understanding the contaminants in your air supply and which filter types can remove them is the first step in selecting the right inline air filter for your system.

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In this article, we'll answer the following questions:

  1. How Does Compressed Air Become Contaminated?
  2. What are Inline Air Filters Used to Remove?
  3. How do Inline Air Filters Work?
  4. What is Considered Optimal Air Quality?
  5. Choosing the Right Inline Compressed Air Filter Setup for Your System

How does Compressed air become contaminated?

A poor air supply can be caused by multiple sources. For example, compressed air can become contaminated from dirty ambient air, humidity, oils leaking from the air compressor, corroded air lines, and even from the air filter itself. Understanding the contaminants and their origin is a good starting point for shops experiencing poor air.

The majority of the contaminants found in an air system are:

  • Liquid water
  • Water vapor (humidity)
  • Oils
  • Oil vapor
  • Dust
  • Dirt
  • Aerosols

The dust and tiny particles in the ambient air around you are the same contaminants that can enter your system while it is running. Contaminants are different-sized microns and can cause varying kinds of damage depending on their form.

Compressed air can also become contaminated from oils within the air compressor, corroded air pipes, and poorly maintained air filters.

Compressed air filters pull out the bulky contaminants - like dust particles, particulates, oils, and liquid water - to prevent equipment damage and maintain air system performance.

What are inline air filters used to remove?

Inline air filters for air compressors effectively remove liquid water, oils, oil vapors, dust, dirt, aerosols and other bulky particulates. There are three types of air filters designed to remove certain contaminants:

  1. Water separators
  2. Oil Coalescing filters
  3. Activated Carbon Filters

1. Water Separators

Water separators are designed to remove large particulates and liquid water.

2. Oil Coalescing filters

Oil coalescing filters pull out oil vapors, small and fine particulates, and bulk oils from the air stream.

3. Activated Carbon filters

Activated carbon filters eliminate odors, tastes, and remove aerosols from the air flow.

How do inline Air filters work?

Each of the three filters - oil coalescing, water separators, and activated carbon - are designed to target specific kinds of contaminants. To get the clean, dry air needed for your application it may require one, two, or even three air filters. This is dependent on which contaminants should be filtered out for your system to work the way it's intended.

These filters work by removing contaminants at a specific micron size: microns are particles that cannot be seen by the human eye. Depending on the amount of air filters installed on a system, the contaminants of different micron sizes filtered out can help the air become clean and dry, or just clean. There are ISO regulations that detail the class, particle sizes, and the pressure they can withstand. This is important to refer to when choosing the right compressed air filter for you.

What is considered optimal air quality?

Air quality requirements are different for every system. There isn't a one-size-fits-all solution when it comes to filtration for equipment - air quality requirements are different for every system. The way to find the filtration required for your air compressor system, is by reading the fine print on the machine and consider the application it is being used for.

There's also a set of standard ISO -05 regulations required for some industries.

It's important to know the filtration needed for specific air systems so they operate at their highest efficiency and do not dysfunction prematurely from not having the right inline air filter.

Download our air system schematic to understand how each air filter pulls out contaminants and how they pair with the most common air dryers.

Are you interested in learning more about hydraulic driven air compressors? Contact us today to secure an expert consultation!

 

choosing the right Inline Compressed Air Filter setup for your system

There are a few considerations to make before purchasing an inline compressed air filter package:

  1. The specific air requirements for your machine or application
  2. The ISO requirements of your system or industry
  3. The desired outcome of the product or process
  4. Other air treatments in place, such as drains, dryers and other filters

We recommend some initial investigation of your compressed air needs and cleanliness goals. Here's a guided checklist to get started on selecting the right inline compressed air filter:

  • Refer to the list above to determine the air cleanliness goals and needs for your system.
  • From there, determine the air demand of your system (10 CFM, 25 CFM , 50 CFM etc..) so the filters can be sized properly. Note: Purchasing larger filters does not mean cleaner air, they will only add cost to your operations.
  • Finally, make sure to choose an air filter that is of higher quality and fits your maintenance schedule. Investing in cheaper products will only add headaches to your operations as they need to be replaced more often.

Ensuring Optimal Performance with the Right Inline Compressed Air Filter

Selecting the right inline compressed air filter is a crucial step towards ensuring the efficiency and longevity of your pneumatic tools and applications. As we’ve explored, understanding the variety of contaminants in your air supply and the specific requirements of your system is fundamental. Inline air filters, ranging from water separators to oil coalescing filters and activated carbon filters, each play a distinct role in purifying your air supply.

Remember, the key to achieving optimal air quality lies not just in selecting the right filter type, but also in considering factors such as your system’s specific air requirements, ISO standards, and the desired outcome of your product or process. It’s not a one-size-fits-all situation; each system requires a unique combination of filters to meet its specific needs.

In conclusion, we recommend conducting a thorough assessment of your compressed air needs and cleanliness goals, followed by consulting with a compressed air professional. This approach ensures that you invest in a high-quality, appropriately sized filter setup that aligns with your maintenance schedule, leading to enhanced system performance and reduced operational costs.

Air Line Filter Buyer's Guide - How to Pick the Perfect Air Line Filter

Air line filters extend the life of your compressor and improve the quality of air being put out.

Aside from filtering out additional moisture from the air, air line filters remove particulates such as dust and dirt.

Browse Air Line Filters

While most users only need general-purpose filters, high-efficiency filters may be needed for medical applications or to protect delicate instruments from contaminants.

For different applications, there are some different options to choose from.

General Purpose Filters

General-purpose air filters are ideal for basic water, oil, and dirt removal. They keep the air moderately clean and extend the life of your air compressor.

Average general-purpose filter elements can catch particulates 5 microns in size. However, some general-purpose filters can catch particulates as small as 1 micron.

Shop General Purpose Filters

Activated Carbon Filters

Activated carbon typically comes from charcoal and highly porous biochar. These air line filters are commonly used in OSHA-regulated breathable air systems.

They offer the largest surface area and lowest pressure drop, meaning more adsorption and less interruption. A major benefit to activated carbon filters is that they remove oil vapors and odor.

Shop Activated Carbon Filters

High-Efficiency Filters

These in-line filters are great if you're looking to conserve energy and filter particulates as small as 0.01 microns. High-efficiency air line filters are ideal for painting applications to eliminate the concern of "fish-eye" flaws in paint finishes.

High-efficiency air line filters are designed to filter more water, oil, and contaminants than other filters while still reducing pressure drop.

Shop High Efficiency Filters

Water Separator Filters

These air line filters are generally used when the main contaminant in your air is water. However, many of them are also able to filter out dirt and oil.

In addition to trapping water at the bottom of the filter bowl, water separator filters also reverse air-flow direction 180-degrees inside the filter and pass it through a stainless steel mesh element.