Autoclaves, also known as steam sterilizers, use a combination of wet heat, pressure, and time to sterilize materials. Autoclaving is one of the most common methods of sterilization utilized. Autoclaves are found across University of Kentucky (UK) campus and are used to sterilize lab glassware, media, and other laboratory supplies, as well as decontaminate biohazardous waste prior to disposal. The total time, temperature, and pressure necessary for sterilization depends on the materials to be sterilized and how they are packaged and loaded into the autoclave, however general cycle parameters for biohazardous waste that must be met are a temperature of 121°C at 15 psi of saturated steam for a minimum of 20 minutes. The total processing time of an autoclave cycle used to process biohazardous waste shall be between 60-120 minutes.
Any autoclave in use at the University of Kentucky must be inspected as to their construction, installation, and condition and certified as a pressure vessel as required by KRS 236.110. Calibration services should be completed by the manufacturer on all new autoclave units, and documentation of this performance shall be maintained with the maintenance records for the unit. To verify calibration, a monthly biological indicator verification shall be completed prior to processing biohazardous waste in the unit.
All autoclave units utilized for decontamination of biohazardous waste materials must be enrolled in the UK Autoclave Verification Program (AVP).
Wet or saturated steam penetrates objects in the autoclave. Condensation creates negative pressure and draws in additional steam. As steam condenses, it transfers heat to the objects in the autoclave and causes cell destruction via coagulation of proteins. Autoclaves can be classified into two different types: gravity displacement and vacuum displacement. Both types can be found on UK campus.
Gravity Displacement – In a gravity displacement autoclave, steam enters the top or side of the chamber and, because steam is lighter than air, it forces the air out of the bottom of the chamber through a drain vent. It is very important that all valves are clear and unobstructed, and the chamber not overfilled for this system to function efficiently. A gravity displacement autoclave can be thought of as a pressure cooker type of system. These often require longer cycle times to achieve sterilization
Vacuum Displacement – In a vacuum displacement autoclave, a vacuum removes cold air from the chamber prior to the introduction of steam. This allows for nearly instantaneous steam penetration into even porous loads. Vacuum displacement autoclaves typically have two sterilization cycles – 1) fast exhaust or high vacuum cycles which is suitable for sterilization of dry materials, and 2) slow exhaust or pressure pulsing which is suitable for sterilization of liquids such that liquids do not bubble out and evaporate during the cycle.
Before utilizing any autoclave, verify that materials are safe for autoclaving:
If autoclaving potentially biohazardous waste, ensure that the autoclave you are using is marked “Designated for Biohazardous Waste.” Autoclaves designated for biohazardous waste are enrolled in the UK Autoclave Verification Program (AVP).
Only CLEAR or ORANGE autoclave bags, marked with the universal biohazard symbol, should be utilized for solid biohazardous waste. Red bags are designated for Regulated Medical Waste (RMW) ONLY and should NEVER be autoclaved.
Before newly installed autoclaves may be used for decontamination of biohazardous waste at UK, the following conditions must be fulfilled:
Inspection & Certification as a Pressure Vessel
Initial Autoclave Verification
Autoclave operation and maintenance manuals shall be maintained by the Responsible Individual or “owner” and provided to service technicians as needed during preventive maintenance and repair activities as needed. Preventive maintenance shall be performed according to the manufacturer’s suggested procedures and schedules. The Responsible Individual must maintain a log of all maintenance activities for each autoclave. Following any significant maintenance activity or repair, the autoclave must be verified by biological indicator prior to processing potentially biohazardous waste in the unit.
Biohazardous Waste: Solid and/or liquid waste that contains or has been in contact with infectious agents, potentially infectious materials, or recombinant/synthetic nucleic acid materials. This may include waste from tissue culture, pipets, flasks, gloves, tips, tips, plates, etc. Any disposable laboratory items that have been in contact with or contain materials which could be potentially infectious to humans, animals, or plants.
Biological Indicator (BI): Test system that contains viable microorganisms with a defined resistance to a specific sterilization process. Designed to verify that the necessary conditions (time, temperature, pressure) were met to kill a specific number of microorganisms for a particular sterilization process.
Chemical Integrator: Test system consisting of a paper wick and steam and temperature sensitive chemicals that undergo a color change when cycle parameters are met. Designed to provide a quick visual confirmation that autoclave cycle parameters were met. NOT a substitute for Biological Indicators (BIs).
Mixed Waste: Waste material that is contaminated with a combination of chemical, biological, and/or radiological hazards. Special consideration must be given to the disposal of this type of waste. Autoclaving is often NOT appropriate for mixed waste.
Regulated Medical Waste (RMW): Pathological waste. Gross specimens of human tissues or organs and large volumes (>500mL) of human blood. Special consideration must be given to the disposal of this type of waste. Incineration is typically required.
Responsible Individual: The individual, designated by the Department or Facility owner of the autoclave facility, tasked with ensuring verification, recordkeeping, preventive maintenance, and training for autoclave facility equipment. Each autoclave on campus should have a designated Responsible Individual.
Verification: Process involving a biological challenge to ensure an autoclave is performing to an appropriate standard to effectively inactivate biohazardous waste. Autoclaves utilized for decontaminating biohazardous waste must be verified monthly.
The UK Autoclave Verification Program (AVP) ensures that biohazardous waste is appropriately decontaminated prior to final landfill disposal. Ensuring that our autoclaves are functioning properly helps keep everyone safe AND keeps research moving forward.
ANY autoclave used to decontaminate biohazardous waste MUST be enrolled in the UK AVP.
Read on below for UK AVP requirements.
The UK Autoclave Verification Program (AVP) is designed to ensure that all biohazardous waste processed via autoclave on UK campus is properly decontaminated prior to final deposition in landfill. It requires monthly testing of the ability of campus autoclaves designated for biohazardous waste to kill microorganisms. ALL autoclaves on UK campuses that are utilized for decontamination of biohazardous waste MUST be enrolled in the UK Autoclave Verification Program. There are two components to the UK Autoclave Verification Program – verification of load parameters for each cycle of biohazardous waste AND monthly verification via biological indicator testing.
AUTOCLAVE DESIGNATION:
The UK Office of Biological Safety, Department of Research Safety, will provide signage upon request.
FOR EVERY LOAD OF BIOHAZARDOUS WASTE:
Autoclaves with automated documentation of load parameters –
Autoclaves without automated documentation of load parameters –
MONTHLY BIOLOGICAL INDICATOR TESTING:
3M ATTEST BIOLOGICAL INDICATOR SYSTEM INDICATIONS & INSTRUCTIONS:
Indications-
Instructions-
TO ENROLL IN THE UK AUTOCLAVE VERIFICATION ONLINE RECORD KEEPING SYSTEM:
Contact UK Biosafety at biosafety@uky.edu.
You'll need the following information ready to enroll...
UK AUTOCLAVE VERIFICATION ONLINE RECORD KEEPING SYSTEM:
Once you have enrolled each autoclave as described on the previous page, you will be prompted to update each record form monthly via email.
Email will arrive with subject line "UK Autoclave Verification Update".
Once you have completed that month's biological verification, click "Open Update Form".
Update the BI test date, the BI test result (pass/fail), and upload a picture of this month's record keeping sheet.
If your autoclave(s) is out of order/down for maintenance, select "Out of Order" from the Pass/Fail menu.
The system will reset according to the Test Date.