Residual oil content, oil content in the compressed air, where does it come from?

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How much residual oil gets into the compressed air line?

Getting a feel for how much oil gets into your compressed air piping system under different operating conditions is not easy.

What is still tolerable for one, can mean for the other already the Supergau. This does not have to be the case, because with OilControl residual oil monitoring, anyone can protect themselves against excessive oil entry or oil breakthrough.


Always remember:

  • High intake temperatures in summer .... low intake temperatures in winter. So the compressor gives more u. less oil.
  • Their machines always suck what is in the environment, which means that all pollutants are compacted with them whether they like it or not.
  • The oil-free compressing are not "oil-free"! If they have oily or vaporizable substances in the environment, they will inevitably be sucked in and concentrated.
  • Or it changes the amount of oil, because the Ölabscheidepatrone for oil separation in the compressor is defective and the compressor throws more oil than normal.

The oil-containing substances and unbranched hydrocarbons occurring in the ambient air are sucked in by oil-free compressors just as in oil-lubricated systems. They just do not add oils from their own system. A well selected and functioning treatment of the compressed air according to the classification is always required. Sometimes more sometimes less.

As the operating conditions change, it soon becomes clear what effects the temperatures, the flow rate and the amount of oil will have as a burden on the filters, and that is very well! It makes sense to protect your pipelines with stepped filtration if you do not want to have a hydraulic line in two or three years.


Once introduced oil into the pipeline, is as good as no longer bring out.

As can be seen in the picture, a pipeline network branches so far that a cleaning is not possible. The entry of oily substances should therefore always be monitored from the beginning, so that it can be ensured that the pipeline remains clean.

Otherwise it simply means:


Drin is drin!

Oil separator in the compressor - what do you let through?

compressor oils

An essential role in the energy-efficient generation of clean compressed air play compressor oils. These account for less than one percent of the cost of operating a compressor, but with the right oil, appreciable savings can be achieved overall.


The oil used in compressors has three important functions:


- It ensures that the rotors in the compressor (compressor stage) are lubricated

- It derives the resulting heat of the compression process

- It forms a sealing film on the sealing edge of the rotor to Verdichtungsgehause and thereby prevents slip losses, since so no gap


For efficient and failure-free production of compressed air, an oil is desirable, which is characterized by long service life, a good temperature behavior and a low residual oil content in the compressed air.

However, there are serious performance differences between the available compressor oils. In general, synthetic products have distinct advantages over mineral oil-based oils.

A well-formulated synthetic product is characterized above all by an optimal oxidation protection, a good durability and a low residue formation (carbon). In addition, a suitable compressor oil ensures that with the same energy expenditure, the specific performance of the compressor is increased.

In principle, a compressor is nothing more than an "oil destruction machine".


Several factors affect the oil:


- High pressure

- Constant supply of fresh air

- High temperatures

- Strong shearing forces

- Constant particle entry by suction (emery effects, enforce the filter)

- The exposure to humidity


All this leads to the aging of the oil, which manifests itself mainly by the oxidation. At temperatures of 90 ° C to over 100 ° C and under constant suction of oxygen, the decomposition is in principle high. This decomposition produces organic acid, which decomposes the oil. The concentration of these acids is expressed by the so-called neutralization number.

The lower this value, the lower the oxidation has progressed. This is achieved by the selection of high-quality additives. Another important factor that leads to increased maintenance is the condensate created by the intake of air humidity. This condensate must be treated prior to discharge into the sewage system. Insufficiently matched oils or the use of inferior additives cause the condensates to be emulsified with the oil and make the oil / water separation in a normal gravity / activated carbon separator impossible.