ISO 12500-1

ISO 12500-1
Filters for compressed air— Test methods—Part 1: Oil aerosols

First edition (2007)

ISO 12500-1 specifies test and inlet (challenge) conditions for compressed air filters for liquid oil separation. ISO 12500-1 determines the residual (liquid) oil content and the according differential pressure 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 10 mg/m³ or 40 mg/m³ of oil aerosols
    • of viscosity grade 46 and
    • with an average (normal mean) particle size of 0,15 µm to 0,4 µm (by number)
  • determination of the residual (liquid) oil content at the outlet of the compressed air filter according to ISO 8573-2
  • three examples of each filter shall be tested while repeating each test three times (total of 9 tests per size and filtration grade)


An inlet challenge concentration of 10 mg/m³ as well as the requested particle size distribution is not really representative for modern compressed air systems.


For liquid separation in compressed air filters many interlinked physical processes are involved, resulting in a multi-dimensional array of working conditions while ISO 12500-1 just supplies a result for one working point in this multi-dimensional array. A “good” filter when tested according to ISO 12500-1 thus may deliver a “bad” performance in a deviant real life operation and vice versa. The result of ISO 12500-1 thus may be misleading and may conclude to a wrong assignment of products in regards of “good” or “bad”.


A compressed air filter series offering 12 filter sizes and 3 filtration grades would require the test of 108 filter elements or 324 total tests. Even a 24h continuous testing would last at least 6 months.