ISO (International Standards Organization) is the world’s largest developer and publisher of international standards.

ISO is a network of the national standards institutes of 159 countries, one member per country, with a Central Secretariat in Geneva, Switzerland, that co-ordinates the system. ISO is a non-governmental organization that forms a bridge between the public and private sectors.

ISO8573 is the group of international standards relating to the quality (or purity) of compressed air. The standard consists of nine separate parts, with part 1 relating to quality classifications for compressed air and parts 2 - 9 specifying the methods of testing for a range of contaminants.

ISO8573-1 is the primary document used from the nine parts of the ISO8573 standard. Importantly, ISO8573-1 contains air purity classification tables which can be used in one of three ways.

1. Compressed air users can use the air purity classifications it contains to specify the amount of contamination allowed in each cubic meter of compressed air i.e. specify the minimum air purity (quality) they require at each usage point in

the compressed air system 

2. Compressed air purification equipment manufacturers can use the air purity classifications to specify the purity (quality) of compressed air delivered downstream of their purification equipment 

3. It can be used to classify the purity (quality) of compressed air at a specific point in the compressed air system