The Quality of Compressed Air


Do you want to set up an air treatment system that meets your application's air quality needs? Learning about compressed air quality is the best place to start. 

What is compressed air quality?

When air is collected to be compressed, other particles are collected too - this air is contaminated. When air is compressed, the concentration of contaminants increases exponentially. In addition, further contaminants could be added during the process of compressing air.

Air treatment is necessary to remove contaminants from the compressed air system. The types of contaminants found in a compressed air system include:

  1. Solid particles / Dust;

  2. Water (in liquid or vapour form);

  3. Oil content (in vapour or aerosol form).

When air is treated properly, it is considered clean and safe. But the quality of compressed air is not only defined by how clean it is but also by how dry it is. To determine how clean and dry the compressed air is, we must count the number of particles of a specific size present in one cubic metre of air, the dew point, and the amount of oil aerosols and vapour. 

What is the ISO air quality standard?

The International Organisation for Standardisation (ISO) has developed the international standard to test compressed air quality, known as ISO 8573-1. The ISO air quality standard measures three types of contaminants present in compressed air: water, oil content and solid particles. It does not consider microorganisms and gases.

A specific compressed air class is assigned depending on the amount of contaminants found. The air quality class is set according to ISO 8573-1. This standardised system defines parameters from the least to most contaminated sources of compressed air.

In the context of compressed air specifications, air compressors are graded according to the purity class after compression. So you can start to determine which type of compressor you need by looking at what air purity class your application requires.

Why is compressed air purity needed?

Compressed air is used in many industries, such as mining, manufacturing, textile production and food processing. The quality of the air used in industrial applications has a direct influence on the work process, installed machines and product quality. It is, therefore, vital for the compressed air to be clean and free from contaminants.

The cleaner the air is, the lower the risk of contamination, breakdowns and product rejection. This is critical in industries like food and beverage, and pharmaceuticals. There is a chance that the air will come into direct contact with the product or indirectly with the packaging.

High air quality is important in many industries, but the most sensitive application is in medical services. In terms of the medical air supply for hospital patients, air purity must be 100% guaranteed. That is where oil-free compressors, which produce the cleanest air, are indispensable.

What does Class 0 mean for air quality?

It is recommended that only compressed air classified as Class 0 be used in critical processes to eliminate the risk of air contamination. This level of classification does not mean zero contamination. Class 0 refers to the highest air quality possible with minimum contamination present in the air and has to be lower in contamination than Class 1.

A combination of compressed air equipment can be installed to produce clean air. This may include various air filters and dryers. Identifying which contaminants need to be removed will help you to determine which equipment you need.

Source: Atlas Copco