Chemical indicators for autoclaves and steam sterilizers play a critical role in sterility assurance programs. There are many types of chemical indicators, such as bowie dick test packs and chemical indicator strips.
All chemical indicators are designed to respond to physical conditions inside the sterilizing chamber. This validates that an autoclave or steam sterilizer is working properly. It also verifies that it met the conditions for sterilization to occur.
Standards for Chemical Indicators
The International Organization for Standardization (ISO) issues many standards for sterilization processes. Chemical indicators must adhere to these manufacturing and application standards, and guidance documents.
ISO 11140-1:2014 is identical to:
- BS EN ISO 11140-1:2009
- ANSI/AAMI/ISO 11140-1:2014
ISO 11140-1:2014 replaces previous standards:
- EN867-1
- ANSI/AAMI ST60:1996
The most current standard is ISO 11140-1:2014. It defines 6 different types of chemical indicators for sterilization.
6 ISO Types of Chemical Indicators for Steam Sterilization
ISO 11140-1:2014 classifies chemical indicators for autoclaves and sterilizers as follows:
- Type 1: Process Indicators
- Type 2: Specific-Use Indicators
- Type 3: Single-Variable Indicators
- Type 4: Multi-Variable indicators
- Type 5: Integrating Indicators (Integrators)
- Type 6: Emulating Indicators (Cycle Verification Indicators)
The types are not ranked by level of importance. Type 1 is not better than type 6. Each type simply denotes performance characteristics and intended use of chemical indicators.
“The classification structure used is solely to denote the characteristics and intended use of each type of indicator when used as defined by the manufacturer. This classification has no hierarchical significance.”
Since performance requirements are distinct, chemical indicators should only comply with one type. This chart summarizes the different ISO types of chemical indicators. It also provides examples of applications and STERIS Life Sciences products available for each type. Use it to help choose the correct chemical indicator for monitoring specific sterilization processes.
6 ISO Types of Chemical Indicators for Steam Sterilization
| TYPES | WHAT THEY INDICATE | APPLICATION EXAMPLE | STERIS LIFE SCIENCES PRODUCTS |
|---|---|---|---|
| Type 1: Process | One or more critical variables in the sterilization process
The unit has been directly exposed to the sterilization process |
Autoclave tape or chemicalindicator strips
Located inside or attached to the outside of packs Provide visual confirmation of exposure to sterilization process |
VERIFY™ Valueline Class 1 Steam Chemical Indicator (PCC009)
Steam Indicator Tape (260010) |
| Type 2: Specific-Use | Defined in relevant sterilization standards for specific test procedure | Bowie-Dick test packs
Test air removal in a prevacuum steam sterilization cycle |
Steraffirm® Bowie-Dick Test Pack (EQC003)
VERIFY™ Bowie-Dick Test Packs (EQC009, EQC010) Daily Air Removal Test–DART® (NB113, NB215) VERIFY™ Bowie-Dick Test Card (S3095) |
| Type 3: Single-Variable | One critical variable in the sterilization process
Exposure to a sterilization process at a stated value (SV) of the variable |
Chemical pellet
Melts at a specified temperature Demonstrates the steam sterilization process has achieved a specified temperature |
Not currently available |
| Type 4: Multi-Variable | Two or more critical variables in the sterilization process
Exposure to a sterilization cycle at stated values (SVs) of the variables |
Chemical indicator tubes
Change color only when exposed to a given temperature for a specified time in a steam sterilization application |
Steraffirm™ Sterilizer Control Tube Steam at 121°C/250°F for: -15 minutes (PCC024) -12 minutes (PCC025) |
| Type 5: Integrating (Integrators) | All critical variables in the sterilization process
Stated values (SVs) meet or exceed performance requirements in the ISO 11138 series for biological indicators |
Moving front indicators
Respond to all critical process parameters |
VERIFY™ Steam Integrating Indicator (PCC065B, PCC065, PCC064) |
| Type 6: Emulating (Cycle Verification) | All critical variables for specified sterilization cycles
Stated values (SVs) are generated from the critical variables of the specified sterilization process |
Cycle-specific indicators
Typically placed in the pack, pouch or container Respond to all critical process parameters for a specified sterilization cycle |
Steraffirm™ Steam Class 6 Emulating Indicators -121°C/ 250° for 15 minutes (PCC012) |
| Critical Variables in Steam Sterilization Time Temperature Steam | |||
From Steris website