What an Air Line Filter is and How it Works - Air Compressors Direct

Without an air line filter - water, oil, and dirt can cause major damage to pneumatic tools, destroy factory equipment, ruin a paint job, and even contaminate food in a production facility.

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Proper air treatment is critical to the health of your air system, and compressor filters are an inexpensive investment compared to a costly repair/replacement job.

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To better understand how these filters work, we will break them down into 8 main components.

1. Air Inlet

As air enters, the internal cap forces it into a downward spiral. Just be sure to size the inlet appropriately for your compressor. You should never use a smaller filter on a larger line.

2. Filter Cap

The filter cap directs the flow of air through the filter. An arrow on the outside of the filter indicates the direction of air flow, and should not be installed backwards.

3. Air Path

In order for the air to be discharged from the filter, it must follow the air path. The air path consists of entering a cyclonic phase and passing through the filter element.

4. Filter Discharge

The filter discharge is the orifice through which the air leaves the filter. The sizing of the discharge should match the inlet size. An under-sized filter will restrict air flow.

5. Filter Element

The filter element is the part that actually filters the air. The filter element catches particulates you wish to remove from the air. As the filter does its job, it becomes clogged with those particulates.

Once the filter is clogged, it will need to be cleaned or replaced. If CFM (cubic feet per minute) decreases, it may be due to a clog in the filter element. Using too fine of a filter element can cause more frequent clogging.

6. Filter Bowl

The filter bowl makes up the largest visible part of the air compressor filter. It connects to the cap housing by either threading into it or twisting and locking into place.

7. Filter Quiet Zone

The filter quiet zone is a zone at the bottom of the filter bowl where contaminants, oil, and water are collected. There is usually a horizontal barrier that hangs down from the bottom of the filter element that prevents debris from becoming re-entrained in the air.

8. Drain

Eventually, the water, oil, and debris in the bottom of the filter bowl must be drained. Some filters come with manual drains, requiring you to periodically remove the plug and drain the contents.

Other filters come with float-operated drains or electric auto drains. Failure to regularly open and drain the collected water and debris will cause the water to rise above the barrier and become re-entrained.

What is a Micron?

Air line filters are measured by the size of the particles they can catch. These particulates are so small they have to be measured in microns (1 micron = one-millionth of a meter). For comparison, a human hair is about 100 microns across and a red blood cell is 8 microns in diameter.

If you are using fine particulate filters, let's say a 5-micron filter, the element inside will trap seemingly invisible particulates smaller than a red blood cell! To avoid immediate clogging of the unimaginably tiny holes in the filter element, it's best to have a general-purpose filter installed upstream to catch larger particulates. Doing so will save you from frequently replacing the small-sized filters, or tossing them altogether!

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Next: Air Line Filter Buyer's Guide

Air Compressor Buyer's Guide Navigation

Compressed air is the lifeblood of many industrial processes, powering everything from paint guns to pneumatic drills. This is a widely used source of power in different sectors including manufacturing and healthcare. But compressed air isn’t always pristine. It can contain contaminants like dust, moisture, and oil aerosols, which can wreak havoc on your equipment and impact the quality of your end product. Here’s where compressed air filters come in.

What is a Compressed Air Filter and Why Do You Need One?

A compressed air filter is a device installed directly into your compressed air system’s pipelines. As the name suggests, it works “inline” to remove impurities before the air reaches its point of use.  These contaminants can originate from the ambient air or even from the compressor itself.  You can ensure clean, dry air by installing an air filter that protects your equipment, improves product quality, and extends the lifespan of your entire compressed air system.

Types of Compressed Air Filters

There are different types of air filters, each designed to target specific contaminants. Choosing the right one depends on the needs of your application. Here’s a breakdown of the most common types:

Dry Particulate Filters: These filters, often featuring a pleated filter cartridge,  remove dry particles like dust, rust, and pipe scale. They’re ideal for applications where moisture and oil aren’t a concern, such as powering pneumatic tools.

Coalescing Filters:  These compressed air filters address both particulate and aerosols. They use a pleated filter cartridge with a special media that allows air to pass through while trapping liquid droplets like water and oil mist.  The coalescing process merges these tiny droplets into larger ones that fall to the bottom of the filter housing, where they can be drained automatically or manually.  Coalescing filters are a must-have if your compressed air system uses a lubricated compressor.

Adsorption (Activated Carbon) Filters:  These filters target gaseous contaminants like oil vapors and odors. They use activated carbon, a material with a vast surface area that attracts and traps these unwanted molecules.  Adsorption filters are often used in conjunction with other filtration stages to achieve extremely high air quality for sensitive applications in industries like food and beverage, electronics, and pharmaceuticals.

The Importance of Inline Filtration

Inline filtration for compressed air is crucial because even small amounts of contaminants can cause significant damage to pneumatic equipment and compromise product quality. For instance, oil and water contamination can lead to malfunctioning valves, clogged orifices, and reduced efficiency in air-powered tools and machinery. Moreover, in industries such as food and beverage, pharmaceuticals, and electronics manufacturing, maintaining clean compressed air is essential to prevent product contamination and ensure compliance with industry regulations.

Benefits of Pleated Filter Cartridges

Pleated filter cartridges are a popular choice for inline filtration in compressed air systems due to their high efficiency and long service life. These cartridges consist of a pleated filter media enclosed within a cylindrical or rectangular housing, providing a large surface area for trapping contaminants while maintaining low-pressure drop. The pleated design allows for maximum filtration capacity and minimal maintenance, making them ideal for demanding applications.

Choosing the Right Compressed Air Filter:

Contaminants: Identify the specific contaminants you need to remove from your compressed air.

Air Quality Requirements: Different applications have varying air quality demands.  For instance, painting requires cleaner air than operating a drill.  Determine the required micron rating of your filter, which indicates the smallest particle size it can remove.

Flow Rate: Choose a filter with a capacity that can handle the airflow of your compressed air system.

Pressure Rating: Ensure the filter’s pressure rating is compatible with your system’s operating pressure.

Conclusion

Compressed air filters play a critical role in maintaining the quality and efficiency of pneumatic systems across various industries. By removing contaminants such as oil, water, and particulates, inline filtration ensures the smooth operation of air-powered equipment. Pleated filter cartridges offer a reliable and cost-effective solution for achieving clean compressed air and should be chosen based on the specific requirements of your application.

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