Oil-free and oil-lubricated compressors: your guide
The different types of air compressors are not limited to the working principle of piston compressors or that of rotary screw compressors. There is also a difference between oil-free and oil-lubricated air compression, no matter what the compressor type. In this article, you’ll find out what that difference is and what you need.
In the case of piston compressors as well as rotary screw compressors, there is a choice between the oil-lubricated and oil-free kind. Both types have their own specific advantages and disadvantages. First, let’s see why both compressors need lubrication in the first place.
- In piston compressors, some sort of lubrication is needed to ensure smooth operation and prevent overheating.
- Overheating is not an issue with screw compressors, but they need it to deliver a continuous airflow. Most screw compressors keep going at full throttle 24/7, which is facilitated by lubrication. Moreover, lubrication elongates the compressor’s life span.
In oil-lubricated air compressors, oil is used to keep everything running smoothly and prevent overheating. This, however, has a few disadvantages:
- The compressed air has traces of oil, which might be an issue in certain applications. However, an additional filter can be installed to ensure that all traces of contaminating oil are removed.
- Oil-lubricated air compressors are often quite bulky and take up a lot of space, making them less easy to move around.
Because of these reasons, oil-lubricated air compressors are often used in industrial settings.They also offer a few advantages:
- Little maintenance is needed and solving technical problems is often quite simple;
- Oil-lubricated air compressors have a long lifespan;
- Because of the thorough lubrication, they produce little noise or heat;
- They can be used in more extreme situations and for heavy-duty work.
Oil-free air compressors use other means of lubrication, for instance pre-lubricated cylinders and an intercooler. An oil-free air compressor does technically contain oil, but that won’t come into contact with the compressor. The oil-free air compressor has a few disadvantages:
- Oil-free air compressors generate more noise and heat than oil-lubricated compressors;
- They have more maintenance requirements;
- They have a shorter lifespan;
- They are not quite suited for heavy-duty use.
Oil-free air compressors are especially suitable in non-industrial settings like dentistry or smaller workshops where contamination is an issue. They are also particularly useful for home or DIY-applications. The advantages of an oil-free compressor:
- They are smaller and easier to move around;
- They deliver clean air without traces of oil;
- No manual lubrication is required;
- They cost less than oil-lubricated compressors.
Once again, the one is not better than the other - it solely depends on what you need.
Both the piston compressor and rotary-screw compressor come in an oil-free and oil-lubricated version. In the latter, oil is mostly used to lubricate, seal and cool the compressed air. In oil-free air compressors, the same is achieved through different means, for instance pre-lubricated cylinders and an intercooler.
It is important to first figure out the exact process the air compressor will be used for. In some applications, even the slightest risk of contamination is not to be taken. For instance:
- Food and beverage industry
- Pharmaceutical industry
- Paper industry
- Electrical manufacturing
In these industries, oil-free air compressors offer an elegant solution. They weigh less and there is obviously no contamination risk.
However, in some - smaller - processes, oil contamination is not an immediate issue. It might be wise to make use of an oil-lubricated air compressor since they:
- require less maintenance
- have a longer life span
- produce less noise and heat
Not sure what type of compressor you should choose?
Would you like more information on the compressors that MARK has to offer? Can we help you decide? Let us know and we’ll answer all your questions as soon as possible.
