# Sterilization indicators

WHAT ARE THE DIFFERENT TYPES OF CHEMICAL INDICATORS FOR STERILIZATION?

ANSI/AAMI/ISO 11140-1:2014 defines six types of chemical indicators:

Class 1 Chemical Indicators
Class 1 chemical indicators are also known as Process Indicators. These types of indicators are external and indicate whether an instrument set has been fully exposed to the sterilization process. Indicator tape and labels placed on the outside of a peel pack are examples of Class 1 chemical indicators.

Class 2 Chemical Indicators
Class 2 chemical indicators are indicators for use in specific tests. These types of chemical indicators are used in specific procedures defined by sterilization standards. For example, Bowie Dick tests are used for a steam sterilizer with a pre-vacuum cycle to check the efficiency of the air removal and steam penetration in the autoclave chamber.

Class 3 Chemical Indicators
Class 3 chemical indicators are known as Single-Variable Indicators. These CIs react to one of the critical parameters (e.g., time, temperature, pressure) of the sterilization process, and indicate exposure to a sterilization cycle at stated values of the specific parameters.

Class 4 Chemical Indicators
Class 4 chemical indicators, also known as Multi-Variable Indicators, react to two or more critical parameters of the sterilization process, and indicate exposure to the cycle at stated values of the chosen parameters. Time and temperature are examples of critical parameters that would be chosen for a steam sterilization process.

Class 5 Chemical Indicators
Class 5 chemical indicators are also known as Integrating Indicators, or Integrators. These CIs are designed to react to all critical parameters over a determined range of sterilization cycles1. The performance of Class 5 Indicators have been correlated to the performance of biological indicators.

Class 6 Chemical Indicators
Class 6 chemical indicators are known as Cycle Specific Indicators and are designed to react to all critical parameters for specified sterilization cycles. For example, each Type 6 CI for a steam sterilization monitors the specific temperature and time of a chosen sterilization cycle.

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