Definitions of chemical indicators
The standard EN ISO 11140-1 contains the definitions of chemical indicators. However colloquial language is different from the definition in the standard.
The figure illustrates the different components of an indicator/indicator system.
Fig. Relation between the components of the indicator
An indicator is a test system in the form it is finally used for testing. According to the standard EN ISO 11140-1 two different product categories are named indicator:
1. Indicator strips where an indicator reagent is placed on a carrier (1)
2. A process challenge device containing an indicator system inside becoming a class 2 indicator (2)
The following overview clarifies the different definitions of colloquial language and standard by means of examples: