ISO 12500-2

ISO 12500-2
Filters for compressed air— Test methods—Part 2: Oil vapours
First edition (2007)
ISO 12500-2 specifies test and inlet (challenge) conditions for compressed air filters for oil vapor adsorption. ISO 12500-2 determines the breakthrough time of a compressed air filter at the standardized test and inlet conditions:

  • nominal volume flow at 7 bar and 20°C
  • inlet challenge concentration of 1000 mg/kg n-hexane
  • determination of the n-hexane content at the outlet of the compressed air filter according to ISO 8573-6 ; time until an n-hexane concentration of 1 mg/kg is measured at the outlet of the compressed air filter (“breakthrough”)
  • three examples of each filter shall be tested


The defined inlet challenge concentration is not suitable for compressed air filter and results in breakthrough times of a few seconds only. Alternatively, sometimes an inlet challenge concentration of 100 mg/kg and a breakthrough limit of 80 mg/kg is applied.


ISO 12500-2 doesn’t consider the equilibrium (adsorption isotherm) of activated carbon and thus the changing adsorption behavior of activated carbon at different load conditions.

At the same time the defined inlet challenge concentration is 10,000-times higher than the typical challenge concentration in a real life compressed air system. A “good” filter when tested according to ISO 12500-2 thus may deliver a “bad” performance in a deviant real life operation and vice versa. The result of ISO 12500-2 thus may be misleading and may conclude to a wrong assignment of products in regards of “good” or “bad”.