ISO 12500-4

ISO 12500-4
Filters for compressed air— Test methods—Part 4: Water

First edition (2009)

ISO 12500-4 specifies test and inlet (challenge) conditions for compressed air water separators. ISO 12500-4 determines the (total) efficiency and the according differential pressure of a compressed air water separators at the standardized test and inlet conditions:

  • 25%, 50%, 75%, 100% and 125% of nominal volume flow at 7 bar and 20°C, alternatively at a higher working pressure
  • inlet challenge of 2 ml/min of water per l/s of nominal volume
  • determination of the residual water at the outlet of the water separator according to ISO 8573-9
  • test time of at least 10 minutes
  • test for each flow condition, repeating each test three times (total of 15 tests)


The inlet challenge of water is only defined by its total quantity, but not how the water is introduced to the compressed air. Thus, water is typically challenged as wall flow. Accordingly, ISO 12500-4 doesn’t supply a result for droplet or aerosol separation of the compressed air water separator.