Which compressor should you choose ? Oil Free Compressor or Oil Lubricated Compressor ?
This is one of the most common but also extremely important question posted to many facility specialists.
An Oil Free Compressor, is normally refer to a compressor that can meet Air quality ISO 8573-1:2010 class 1 standard.
In this class 1 standard, it specify the compressed air should contain oil vapor less than 0.01 mg/m3. Thus, compressors that generate compressed air meeting this standard is commonly called Oil Free Compressor.
Typical Oil Free Compressor in the market are : Oil Free Screw Compressor, Centrifugal Compressor, Oil Free Piston Compressor, Oil Free Scroll Compressor and also Water Injected Screw Compressor.
In these type of compressors, the compression process take places without the presence of oil , therefore no oil vapor is introduced into the air.
Oil Free type Compressor should be used in Food & Beverage industry (for process air, in contact with food or beverage), Medical Air, Semi-Conductor Industry, Breathing Air, Pet Bottle Blowing or any applications where oil vapor is not allowed.
On the other hand, Oil Lubricated compressor is referring to those compressor not able to meet the Class 1 standard, for example Oil Lubricated Screw Compressor.
Commonly, Oil Lubricated (or some call it Oil Injected Screw) compressor is used as source of power for Pneumatic application, like power tool, pneumatic valve or cylinders.
Some compressor vendor offers “technical oil free” solution. This mean, the compressed air generated from Oil Lubricated Screw Compressor will go through Carbon Filters (or any oil removal filtration) to remove the oil vapor, in order to meet the Class 1 standard. This is not a bullet proof solution, as human oversight in replacing the soaked filter elements will render the system to fail.
Currently, only a few compressor vendors have the technology know how to build Oil Free Screw Compressors and Centrifugal Compressor, therefore the price of these compressors will be much higher than Oil Lubricated Screw Compressor. The price difference is as much as 2x to 3x, which may not reflect the actual cost to build it.
Using “Technical Oil Free” solution is very high risk. My previous job was in a International F&B manufacturing plant. The plant was using an Oil Lubricated compressor + carbon filter as the source of air to do the filling of the 3-in-1 coffee powder. Guess what, one day the powder was discovered by the operator, to have smell. After 2 days of investigation, the smell was traced by to the Compressor oil. One of my colleague did not change the carbon filter element for 9 months ! The filter element was soaked with oil, and this oil vapor was pushed into the production floor.
So, instead of 3-in-1, the coffee powder become 4-in-1 !
Our management has learned the lesson and immediately change the system to Oil Free Compressors.