Educational exam prep, not medical advice. This page teaches what certification exams test. Follow your facility’s policies, your supervising clinician and the manufacturer’s instructions in practice. If you are a patient with a health question, talk to your clinician or see MedlinePlus.
Typical steam cycles for wrapped items (CDC)
| Sterilizer type | Temperature | Exposure time |
|---|---|---|
| Gravity displacement | 121 C (250 F) | 30 minutes |
| Gravity displacement | 132 C (270 F) | 15 minutes |
| Dynamic air removal (prevacuum) | 132 C (270 F) | 4 minutes |
Monitoring
| Tool | What it tells you |
|---|---|
| Bowie-Dick test | Air removal in dynamic-air-removal sterilizers; run daily in an empty chamber, usually the first cycle |
| Biological indicator (BI) | Whether spores were killed: Geobacillus stearothermophilus for steam and hydrogen peroxide; Bacillus atrophaeus for EtO and dry heat |
| Chemical indicators (ISO 11140-1 types 1-6) | Type 1 process indicators (tape); Type 2 specific tests (Bowie-Dick); Types 3-6 single-variable, multi-variable, integrating and emulating |
| Mechanical monitoring | Cycle printouts/displays of time, temperature and pressure for every load |
Low-temperature methods
| Method | Key points |
|---|---|
| Ethylene oxide (EtO) | For heat- and moisture-sensitive items; requires aeration to remove toxic residue |
| Hydrogen peroxide gas plasma / vapor | Low temperature, no toxic residue; cellulose (paper, linen) and liquids are not compatible |
Spaulding classification
| Category | Contacts | Minimum processing |
|---|---|---|
| Critical | Sterile tissue or the vascular system | Sterilization |
| Semicritical | Mucous membranes or non-intact skin | High-level disinfection (minimum) |
| Noncritical | Intact skin | Low-level disinfection |
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Frequently asked questions
What is a Bowie-Dick test?
A daily air-removal test for dynamic-air-removal steam sterilizers, run in an empty chamber.
Which organism is used in steam biological indicators?
Geobacillus stearothermophilus spores.
What is the Spaulding classification?
A system that ranks devices as critical, semicritical or noncritical by infection risk and sets the minimum processing level for each.
Sources
- CDC - Guideline for Disinfection and Sterilization in Healthcare Facilities (2008, updated) (accessed 2026-09-23)
- HSPA - CRCST Exam Content Outline (revised November 2023) (accessed 2026-09-23)