FAQ: EPA/Oil Water Separators

Keeping Your Air Compressor Compliant

In most instances, the air compressor you operate will use oil to lubricate the mechanism. Though this oil is collected, filtered and reused, it eventually comes to the end of its use and ultimately must be drained and replaced. Because environmental regulators levy fines for contamination, an oil/water separator was developed to filter out much of the oil from air compressor drainage.

How your compressor uses oil

There are many options for water lubricating or oil-free compressors, but they are less common. Oil lubrication is preferred because of its efficiency and protection. Compressors use oil to lubricate and protect their moving parts. Oil also helps to cool rotors and pistons, and provides a tight seal which is very important for reaching higher pressures.

In a typical air compressor, ambient air is drawn through a filter on the outside, and pulled through a valve which prevents oil from moving the wrong direction. Oil is delivered to cool and seal during the compression process, and the runoff is collected in a tank. This tank is used as a reservoir, and usually has a visible gauge for checking the level of the oil inside.

Much of the oil is separated here from the compressed air, and it gets recirculated back into the mechanism. If the oil is too hot, a sensor diverts it to a cooling apparatus. Once the oil has reached the proper temperature it is mixed back in and the compression process continues.

EPA Oil/Water Separators

The Environmental Protection Agency, or EPA, defines expended oil as a pollutant, and places restrictions on air compressors regulating the amount of oil that can be discharged. This is specified as 15 parts per million, but applies widely to any amount that causes a sheen on the surface of wastewater. This applies to the runoff many compressors discharge in their drainage. Oil/water separators contain particles which attract oil and attach it to a filtering bed, reducing the amount of oil in the runoff to acceptable levels.

Because this keeps groundwater from becoming contaminated and keeps the users of air compressors in compliance with EPA regulations, they have become a necessary component of compressor use. Without proper Oil/Water separation, air compressor operators could find themselves facing big fines. It’s not only the right thing to do, it’s simpler and more efficient to comply.