Air Compressor Works

What Type of Filter do I Need?

September 30, 2020
Very confused person

Separator/Water Droplet Removal:

This is simply a separator that is used at the outlet of your compressor, or remote aftercooler, to collect and drain the water droplets hat are formed when the temperature in the system is lowered. It is critical to have demand type auto drain to remove the water that will accumulate in the high humidity high temperature days. Service life is 2-3 years or 12000 hours.

Particulate/Bugs and Rocks Removal:

A must have filter for all compressor systems. Normally used for air tools, sandblasting and general shop use. This type of system requires a particulate filter rated for 3 µ micron/ISO Class 2.4.4 to remove solid contaminants and remove major oil droplets, so that you will have relatively clean air in the system. This filter is usually placed after the receiver or dryer. A demand type auto drain is also required. Most point of use filters that are seen on pipe drops are of this type. Service life is up to one year or 8000 hours.

water condensation

Coalescing/Oil Removal:

When you want to take the next step in cleaning up your system to provide little or no oil downstream. Install a standard or fine coalescing filter with a rating of .01 µ micron/ISO Class 1.4.2. The normal application would be where oil is not acceptable such as instrument air, paint spraying, powder coating and other production equipment. When installing this filter it would normally go after the refrigerated dryer, with the particulate filter moving to in front of the dryer. As with the particulate filter, a demand type auto drain is required. We do not normally recommend this type of filter without a refrigerated dryer. Service life depends on the amount of oil contamination and is normally 3000 hours or six months.

Vapor/99% Clean Air:

Install a carbon vapor filter for tasteless and odorless air. Meeting Class 1.2.1 requirements for pharmaceutical/chemical/food/laboratory environments. This type of filter requires a particulate filter and coalescing filter, along with a refrigerant or desiccant dryer to be effective. Properly installing this filter will be the final step to remove 99% of the contaminants produced by compressor. No auto drain is required because the carbon element actually absorbs the vapor. Testing has shown the air can be cleaner than the compressor inlet air. Service life is 2000 hours maximum and must be changed every six months to be effective.

If its’s breathing air (sterile air) requires additional filters added to the system. A particulate/coalescing/vapor filter set with the appropriate drying system. Breathing air must have special safety devices including a carbon monoxide monitor. It is not safe to breathe air from anything other than a certified breathing air system.

Adding a proper filtration system in the compressor room may not clean up the issues that exist in the pipe headers and drops. Specialized point of use filters will be required and should be selected based on each application.

kaeser filters

So, the bottom line is that we can make the air cleaner than you are currently breathing, but it’s done at a cost. Each filter has a 3 to 5 PSI pressure drop from clean the dirty. Three filters inline, that are all dirty, could create up to a 15 PSI combined pressure drop.

For more information on assistance in selecting filters for your system please contact the ACW Sales team at or call (800) 345-4364

Related Post

Oil and Water Don’t Mix. Your air compressor makes water every day. Oil is in that water.

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