How Do Oil-Free Air Compressors Work?

If you have an oil-free compressor, it’s important to understand how it works in case you ever need air compressor repair. The first thing to understand is that the device actually does contain oil. However, the oil will not be in contact with the compressor—the oil is only in the gearbox.

Here’s how it works.

Step 1: Drawing in air

The first step your oil-free compressor takes is to draw in outside air through an unloader valve and pass the air through a filter. The filtering process keeps dust and debris out of the unit. The valve opens to load the compressor, then closes. Once it closes, the compressor is unloaded and starts to run. At this point, the compressor does not draw in additional air.

Step 2: Compression

The compressor element will compress the air and move it through the unit to cool it down. Compressor elements typically generate a lot of heat, causing the unit to operate at up to 180 degrees. This is much hotter than oil-lubricated compressors.

Step 3: Intercooler cooling

After the air is compressed, pistons push it through the intercooler. Here, the air is cooled so the unit can further compress it. This also minimizes the risk of damage due to heat. The process of cooling may cause condensation, so your oil-free compressor may also feature a moisture trap.

Step 4: Second compression

After the air is cooled, it returns to the compressor for a second round of compression. The high-pressure element will further compress the air, typically achieving a maximum pressure of 116 to 143 psi (pounds per square inch). This process generates even more heat, so cooling is again necessary.

Step 5: Aftercooler cooling

When the air undergoes the second round of compression, it can reach temperatures as high as 150 degrees. To cool the air down, it enters the aftercooler. The air passes through a check valve on its way to the aftercooler to prevent backflow. Your oil-free compressor may also feature a dampener, which reduces vibrations caused when valves open and close. Once the air has been cooled, it is stored or used.

Step 6: Monitoring

A pressure switch monitors how much air is left in the compressor. If the volume falls below a certain level, the compressor will turn on and rebuild more pressurized air for the tank. If the pressure switch fails, the compressor will not refill and will require air compressor repair.

Benefits of an oil-free compressor

You may wonder if an oil-free compressor offers any advantages over other compressor styles. Following are the top benefits of an oil-free compressor:

  • Low maintenance: Because no oil is used in the process, you do not have to collect or dispose of oily condensate. Additionally, because the filters are not handling oil, they require less frequent replacement.
  • Low energy use: Oil-free compressors use less energy because they don’t need to increase force for oil filtration.
  • Reduced cost: You don’t have to constantly refill the compressor with oil, so the oil-free compressor saves you money.

Learn more

To learn more about air compressor repair or oil-free operation, contact the experts at Wenniger Compressor Co. Our team specializes in air compressors, high-pressure air compressors and more. Reach us today for professional input at 414-372-5320.

Read More