Autoclave Testing Program

Autoclaves need periodic testing to ensure proper functioning.  Oregon Public Health regulations require that autoclaves used to decontaminate regulated wastes such as cultures and stocks be tested monthly by challenge testing using biological indicators containing endospores of the bacterium Geobacillus stearothermophilis. 

OSU Biosafety offers autoclave testing kits to researchers or other users on the campus. The kits contain a vial of endospores, information card and return packaging.  Users are asked to bury the vial inside a bag of waste, run it in the autoclave, then retrieve the vial and return it to EHS for evaluation. A report of the results is generated and sent to the user for their records.

Autoclave Operation

To safely decontaminate solid bagged waste, leave the bags closed and place them in secondary containment so any leaks will be captured.  Do not overfill the autoclave with bags; one bag at a time is recommended unless the autoclave is very large.  Steam must be able to contact all surface areas of the bag. Use heat tape or a temperature chart recorder to validate that each run reaches the appropriate temperature (usually 121 degrees celsius).  For waste bags, usually one hour of run time is required; some campus autoclaves need more time.  A dry cycle can be used.

After the autoclave has come returned to ambient pressure, carefully open it an inch or two to allow excess steam to escape before opening the door completely.  Use thermal gloves to handle hot materials when removing them from the autoclave.

Biohazard Waste Autoclave SOP (pdf)

Autoclave Safety & Testing

Autoclaves are essential tools for sterilizing biohazardous waste and laboratory materials. To ensure safety and effectiveness, Oregon State University requires either monthly or quarterly biological indicator testing and encourages best practices for operation and maintenance.

Monthly Autoclave Testing

All autoclaves used for biohazardous waste must be tested monthly using biological indicators. This ensures that the autoclave is effectively sterilizing materials.

How to Test:

  • Use the provided test kits with Geobacillus stearothermophilus spores.
  • Follow the instructions included with the kit.
  • Submit tubes back to Environmental Health & Safety (EHS).

Need a Kit? Contact EHS Biosafety to request autoclave test kits.

Autoclave Safety Guidelines

Autoclaves operate under high pressure and temperature, posing risks if not used properly. Follow these safety tips:

Before Use:

  • Inspect door seals and gauges.
  • Wear appropriate PPE: lab coat, heat-resistant gloves, eye protection.
  • Ensure materials are autoclave-safe (no sealed containers, volatile chemicals, or incompatible plastics).

During Use:

  • Load items loosely to allow steam penetration.
  • Use secondary containment trays.
  • Never open the door until pressure and temperature return to safe levels.

After Use:

  • Allow items to cool before handling.
  • Check for cycle completion and any error messages.

Downloadable Safety Poster: OSHA Autoclave Safety QuickFacts (PDF)

Autoclave Maintenance Best Practices

Routine maintenance helps ensure autoclave reliability and safety.

Recommended Practices:

  • Schedule annual calibration and preventive maintenance.
  • Clean chamber and drain screens regularly.
  • Monitor temperature and pressure gauges.
  • Keep a log of maintenance and test results.

Performance Verification SOP: EPA QC-13-12 PDF

Training Resources

Proper training is essential for safe autoclave use. OSU and national organizations offer helpful resources:

Frequently Asked Questions

  • What if my autoclave fails the test? Contact EHS immediately. Do not use the autoclave for biohazardous waste until it passes a retest.
  • Can I autoclave sealed containers? No. Sealed containers may explode due to pressure buildup.
  • What types of waste can be autoclaved? Only biohazardous waste that is compatible with steam sterilization. Do not autoclave chemical, radioactive, or pharmaceutical waste.

  • Can I autoclave bleach or bleach-containing waste? No. Autoclaving bleach can release toxic chlorine gas and damage the autoclave. Dispose of bleach-containing waste according to chemical waste procedures.
  • How do I know if my autoclave cycle was successful? Check for complete cycle indicators (e.g., temperature, pressure, and time met), absence of error messages, and confirm with biological indicator results.
  • Can I autoclave liquids? Yes, but only in vented containers with loose caps. Use a liquid cycle to prevent boiling over or container rupture.
  • What should I do if I see residue or melting after a cycle? This may indicate improper materials were autoclaved. Review the material compatibility list and contact EHS for guidance.
  • How often should I clean the autoclave? Weekly cleaning of the chamber and drain screen is recommended. Follow manufacturer guidelines for deeper maintenance.
  • Do I need to log each autoclave use? Yes, maintain a log of use, including date, operator, cycle type, and any issues encountered. This supports compliance and troubleshooting.
  • Who is responsible for autoclave maintenance? Typically, the lab or department that owns the autoclave. Contact your building manager or EHS for support or referrals.
  • Can I use tape or autoclave bags with biohazard symbols? Yes, but ensure they are rated for autoclave use and do not obstruct steam penetration.

For questions or assistance, contact EHS at [email protected]