By: Brad Taylor

The Why and How of Oil Water Separators

Why Do You Need One?

Compressed air produced by any oil flooded compressor has contaminates. After the air is cooled by the heat exchanger and/or the dryer, the contaminants including water and oil condense and become a liquid. To properly dispose of this liquid, the oil needs to be removed from the water so that the water can be reintroduced to the municipal water system. This can be achieved through the use of air compressor oil separator.

If you do not use an oil/water separator and you dispose of the liquid from your dryer by dumping it into your usual water system, collecting it in a bucket and dumping it outside, or doing some other non-environmentally friendly method, you could find yourself trying to explain to the government why you’re polluting the water.

The Clean Water Act – EPA
Code of Federal Regulations – Part 279, Title 40

The US government states that water drained into the municipal system must have 40 PPM (Parts Per Million) or less of oil in the waste water. Liquid that is dispensed from the dryer and/or pre-filtration & post-filtration usually contains approximately 300 PPM of oil to water.

How Do They Work?

Each brand of oil water separator operates a little bit differently, but they all use the underlying principle of adsorption. Adsorption is the concept that something (usually a liquid) will stick to the outside of something else (usually a solid).

By directing the compressor system condensate from the dryer and/or filtration into an oil water separator, this piece of equipment collects the oil on polypropylene fibers and then purifies the water through activated carbon media. The water is then dispelled and can be drained into your usual water system. The oil will be collected and stabilized on the polypropylene fibers and disposed of correctly when doing the regular industrial air compressor maintenance.

CSO 40-80:The Why and How of Oil Water Separators


CSO 150-1250:

The Why and How of Oil Water Separators