Environmental, Health and Safety Services

Autoclave Use and Verification Program: Requirements

Cycle Optimization

  • Factors which must be considered for determining cycle types and times include:
    • Shape/size/volume of containers and materials
    • Thermoconductive properties of containers and contents
    • Density of solid materials and viscosity of liquids
    • Position of load within the chamber
    • Load configuration
  • For most biohazardous wastes, the autoclave must reach and maintain the following conditions at the most difficult location of the load to heat (e.g., inside of a package, autoclave bag): 121ºC and 15 psi for at least 30 minutes. However, longer lengths of time or greater temperatures or pressures may be needed for some materials.
  • Because the entire waste load must be exposed to the appropriate conditions, denser loads will require longer run times for effective steam/heat penetration. Cycle parameters for such loads must be developed, primarily by adjusting cycle times, so that successful sterilization is achieved.
  • Waste decontamination loads should always be run separately in the autoclave from loads of goods to be sterilized for use.
  • For every waste load that is decontaminated, regardless of cycle type, processing time, load composition or load configuration, a Class 5 Chemical Indicator (CI) must be used to determine sterilization effectiveness. This measure is necessary to ensure that waste, after autoclaving, can be handled and disposed of safely, and thus protects the health of research personnel as well as the general public.

Load Configuration

  • Always configure a waste load in a manner that avoids stacking, crowding, and touching the sides of the autoclave chamber. Load the waste to allow for air flow around waste containers.
  • Once a commonly-used load configuration has been proven to decontaminate waste successfully, it is recommended that it be documented and posted for reference by other autoclave users to save time, resources, and utilities.

Load Composition and Preparation

  • Primary containers must not be filled beyond 75% of holding capacity and must be made of materials that will remain structurally intact during autoclaving.
  • All primary containers must allow steam penetration through loosened, vented openings or permeable materials.
  • Secondary containers must be used which are deep enough to contain spills (e.g., Nalgene or stainless steel pans).
  • SPECIAL CONSIDERATIONS FOR LIQUIDS:
    • Bottles or flasks of liquid waste, as well as liquids to be sterilized for further use, must ALWAYS be run using a Liquids Cycle that includes a slow exhaust to avoid boil-over.
    • Do not decontaminate solid waste and liquid waste (in bottles or flasks) together in the same load.
    • Minute volumes of liquid waste (e.g., in Petri dishes, conical tubes, microtiter plates, or vials), when bagged, can be mixed with solid waste (e.g., disposable gloves, paper towels) and autoclaved successfully using a Solids/Gravity cycle or Prevacuum cycle.
    • Do not autoclave liquid waste containing hazardous chemicals or oxidizers.

Performance Verification/Monitoring

  • New Autoclaves
    • Before placing a new autoclave into service, performance verification using a Biological Indicator (BI) test must be conducted and documented for each cycle programmed (i.e., each cycle type, time, and temperature) and used for decontaminating infectious and biohazardous waste.
    • Waste must not be decontaminated in a new autoclave until the unit passes this performance verification test.
    • To perform this verification, BI vials must be 1) within a commercially available challenge test pack, or 2) placed in a central position within a mock load of waste, to offer sufficient challenge for steam penetration.
    • Self-fashioned test packs which simulate commercial products can be tested and used with EHSS approval.
    • Results must be recorded in the Biological Indicator Test Results Log.
  • Each Load
    • Each load processed in an autoclave must meet the operating parameters set up for that particular cycle, determined by the use of a Class 5 CI.
    • Any load which fails to be exposed to the operating parameters must be processed again.
    • Performance verification per load must occur as follows:
      • An externally placed, Class1 CI (i.e., autoclave indicator tape) must be used with each container, bag, or item processed in order to distinguish it from unprocessed materials.
      • For every load, the user must verify and document operating parameters using an internally placed Class 5 CI. Chemical Indicators must be 1) within a commercially available challenge test pack, or 2) placed in a central position within the load. Products are available which aid in the placement and retrieval of CIs from within bags of waste.
    • Self-fashioned test packs which simulate commercial products can be tested and used with EHSS approval.
  • Monthly Performance Testing
    • Operating parameters (i.e., time, temperature, and pressure) for each programmed cycle (i.e., cycle type, time, and temperature) used for decontamination must be verified monthly by BI testing.
    • To perform this verification, BI vials must be 1) within a commercially available challenge test pack, or 2) placed in a central position within an actual or mock load of waste, to offer sufficient challenge for steam penetration.
    • Self-fashioned test packs which simulate commercial products can be tested and used with EHSS approval.
    • Results must be recorded in the Biological Indicator Test Results Log.

Performance Failures

  • Sterility Not Achieved
    • Any of the following must be taken as an indication that sterility was not achieved:
      • Printout of process parameters shows sterilization conditions not met
      • Autoclave malfunctions, aborted cycles, or alarms during a cycle
      • Failure of monthly Biological Indicator Sterility Test
      • Failure of CIs to show adequate processing occurred
  • Failure Responses
    • Autoclave malfunction (e.g., printout, alarm, aborted cycle, power failure)
      • The Responsible Technician must be notified immediately and the autoclave taken out of service for waste processing until the problem is rectified.
      • The Responsible Technician will determine if service personnel are required to restore function and will arrange for repairs, if needed.
    • Failure of a Biological Indicator Test
      • The Responsible Technician must be immediately notified of any BI test failure and the autoclave taken out of service for waste processing until the cause of the failure is found and rectified.
      • Positive test results from BI can result from a variety of causes, such as inadequate steam quality, insufficient exposure time or temperature, poor loading practices, or product failure or operator failure.
      • All possible causes should be investigated by the Responsible Technician.
      • Proper autoclave function must be verified using repeat BI testing by the Responsible Technician.
      • Once verified, the autoclave may be returned to service for waste processing.
    • Failure of Chemical Indicators (Class 1 or 5)
      • The Responsible Technician must be immediately notified of any CI failure and the autoclave taken out of service for waste processing until the cause of the failure is found and rectified.
      • CI failures can result from a variety of causes, such as inadequate steam quality, insufficient exposure time or temperature, poor loading practices, or product failure or operator failure.
      • All possible causes should be investigated by the Responsible Technician.
      • Proper autoclave function must be verified using repeat CI and/or BI testing by the Responsible Technician.
      • Once verified, the autoclave may be returned to service for waste processing.
  • Autoclave Calibration
    • May be performed on an autoclave by a service provider when other causes of performance failure have been eliminated.
    • Some preventive maintenance contracts may include an annual instrument calibration check.

Documentation

  • Users Training Log
    • Maintained by the responsible technician
  • Autoclave Use Log
    • Must be maintained separately for each autoclave
    • Must be located in close proximity to the autoclave
    • All runs must be documented
  • Service Log
    • Must be maintained separately for each autoclave
    • Responsible technician must document maintenance, repair, and calibration services in this log
  • Biological Indicator Test Results Log
    • Must be maintained separately for each autoclave
    • New autoclave and monthly test results must be recorded in this log