ISO 8573 is broken into nine equal parts as listed in INTERNATIONAL STANDARD ISO 8573-1:2001 as follows:
Part 1: Contaminants and Purity Classes
Part 2: Test methods for aerosol content
Part 3: Test methods for measurement of humidity
Part 4: Test methods for solid particle content
Part 5: Determination of oil vapor and organic solvent content
Part 6: Determination of content of gaseous contaminants
Part 7: Test methods for viable microbiological contaminant content
Part 8: Contaminants and purity classes (by mass concentration of solid particles)
Part 9: Test methods for liquid water content
Note: Each part addresses the requirements to certify the compressor. Part 1, “specifies purity classes of compressed air in respect of particles, water, and oil regardless of the source of the compressed air.”