Oil Lubricated Vs Oil-Free Air Compressors
One of the major decisions you have to make when buying an air compressor is whether to buy an oil-lubricated or oil-free kind. In order to be able to make an informed decision, you need to understand and compare how these two different machines operate, and how they affect the work you intend to use them for.
Some writers say that to refer to an “oil-free” or “oil-less” compressor is a misnomer because even they need oil to run their motors and gearboxes. The only part that is truly oil-free is the compression chamber. On the other hand, oil-lubricated types need oil not only for their motors and gearboxes but also for the compression mechanisms.
Owing to the presence of oil in the compression chamber of oil-lubricated compressors, the air sent into the tanks necessarily contains traces of oil particles either as mist or vapor. Oil within the air lines and the tank can prevent rust which could result from the condensation of moisture from the air drawn in.
While there are certain pneumatic tools that actually require air with traces of oil, other applications need just the opposite. When spray painting, for instance, you would not want oil mixed with your paint. This may be resolved with the use of filters that can minimize, though not eliminate, the presence of oil. In pharmaceutical, food, and other biological applications, however, not even the slightest trace of oil can be tolerated. For these, oil-free compressors are mandatory.
Oil splashing around within the compression chamber keeps temperatures down as it lubricates the moving parts. It also absorbs sound waves from the equipment. The lower temperature reduces stress on the machine potentially resulting in a longer life span. It also allows extended operation for hours without overheating. And because it is quieter, it is often preferred for indoor work.
The absence of oil in the compressor, on the other hand, eliminates the possible clogging of the air lines with oil deposits which could lead to expensive and time-consuming repairs and replacements. Oil filters are also unnecessary.
In terms of the pressure produced, oil-lubricated compressors beat oil-less types, although the latter are often quite capable of coming up with 150 PSIG.
In the end, the single most important question you need to answer is: What am I going to use the compressor for?