ISO 11140-4:2007 specifies the performance for a Class 2 indicator to be used as an alternative to the Bowie and Dick-type test for steam sterilizers for wrapped health care goods (instruments, etc. and porous loads).

An indicator complying with ISO 11140-4:2007 incorporates a specified material which is used as a test load. This test load may, or may not, be re-usable. ISO 11140-4:2007 does not specify requirements for the test load, but specifies the performance of the indicator in combination with the test load with which it is intended to be used. The indicator specified in ISO 11140-4:2007 is intended to identify poor steam penetration but does not necessarily indicate the cause of this poor steam penetration.

This part of ISO 11140-4:2007 does not include test methods to establish the suitability of these indicators for use in sterilizers in which the air removal stage does not include evacuation below atmospheric pressure.