By Ricardo Pires

Why should I use true oil free air compressors?

A lot has been said and written about the presence of oil in compressed air. Some defend that for a few processes and end products, it is ok to have a certain amount of oil in the air used while others say that ideally there should not be any oil in compressed air, independently of the process and end products.

Although, everyone can agree that the best solution is to avoid the presence of oil in compressed air all together.

But how to guarantee that the air used in a process is truly oil free, i.e., 100% oil free? Only a compressor that has gained a TÜV Class 0 certification under the ISO 8573-1 can be classified as truly oil free. We should make sure that when using a compressor labeled by the manufacturer as “oil free” the compressor has the correct TÜV classification. We should be advised that some compressors are labeled “oil free,” but they are actually only “technical” oil free.

What are the differences between a truly oil free compressor and a “technical” oil free compressor and is it such a big deal to rent the latter instead of the former?

The evolution of ISO standards has been reflecting the need of the market for increased quality air for process and end products. A more stringent class of oil content measurement was created by an international independent organization, TÜV, to reflect this evolution. Not only is oil presence measured in aerosols and liquid form, but also in vapor form.

Let’s compare a class zero compressor with a technical oil free compressor. First, there is absolutely no oil in the air of an oil free compressor while in a “technical” oil free compressor, oil is actually injected in the air and removed afterwards using a filtration process. This procedure involves several parts such as an oil separator, coalescent filters and activated carbon filter to remove vapors. Now, the problem is that during the filtration process failures can happen. A separator can break or a filter can be saturated quicker than expected contaminating the process and the end product. Besides that, the lifetime of the “technical” oil free machines can be short at high temperatures.

Another disadvantage of a “technical” oil free machine is its high maintenance. The machine has to undergo regular interventions to change the filters and to treat the condensate, leading to higher energy costs.

When using true oil free air compressors, you do not have any of these concerns. Also, you have your safety and environmental problems covered.