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Technology, Service, Parts & Maintenance

Clearing Your Compressed Air of Unwanted Substances


The introduction of unwanted substances, such as water, oil and dust, into your compressed air system can impair production results and even increase costs. Not to mention, your end uses will be affected by the lower quality of air. Luckily, there are several options available for clearing your compressed air of unwanted substances.


Compressed air is very hot after it’s compressed. An after-cooler is used to lower this temperature, which in turn reduces the water content. After-coolers are frequently included as standard equipment for compressor installations and should be placed directly after the compressor. The heat exchanger cools the hot air and then routes most of the condensation water away from the system as quickly as possible. 

Water Separator

With proper sizing and selection, a water separator can achieve an 80-90 percent efficiency in separating condensation water from the compressed air. The remaining water flows with the compressed air as water vapor into the air receiver. 


A correctly installed coalescing filter, together with a suitable pre-filter, can reduce the quantity of oil in compressed air to approximately 0.01 mg/m3. With an activated carbon filter, the quantity of oil can be reduced to 0.003 mg/m3.


Many systems require a much higher degree of air drying than filters and water separators can provide.  In that case, a dryer is used to reduce the moisture levels below the point where condensation can occur later in the system.  For most systems, this would mean a refrigerated dryer that removes the water by cooling the air to a temperature near freezing.  When even dryer air is needed, a desiccant type dryer is required.  This type of dryer reduces the water content by adsorbing the water onto specially designed media.

Oil/Water Separator

Oil/water separators are an easy and cost-effective solution for meeting new and more stringent laws with regards to handling environmentally hazardous oil waste in your condensate. Absorption media traps oil to produce clean drainage water.

Understanding the quality of compressed air needed is the first step in determining an air filtration solution suited for your applications. Have you used filters, after-coolers or water separators in your system? Leave us a comment below and tell us how they’ve impacted your compressed air system.

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