Autoclaving Guidelines for Biohazardous Waste

All autoclaves can sterlize and decontaminate laboratory materials. However, only a few UCSD autoclaves are calibrated and permitted by San Diego County to process biohazardous waste.

• Look for a label that reads either "Calibrated for biohazardous waste" or "Not calibrated for biohazardous waste."

For efficient heat transfer, steam must flush the air out of the autoclave chamber. If the drain screen is blocked with debris, a layer of air may form at the bottom of the autoclave and prevent proper operation.

• Check the drain screen at the bottom of the chamber before using the autoclave. Clean out any debris.

• Ensure that dry waste is free of liquids and sharp objects that could puncture the waste bag. Treat biohazardous waste that could puncture the bag as sharps.
• Read How to Package and Dispose of Biohazardous and Medical Waste for detailed instructions on how to double-bag and label waste in red biohazardous waste bags.
• Fill bags only half full. Ensure adequate steam penetration by closing bags loosely, leaving a 1-inch opening.
• Place bags in a secondary container. Polypropylene bags are tear-resistant but can still be punctured in the autoclave. Place bags in a rigid secondary container during autoclaving to eliminate the primary cause of damage to the machines and reduce downtime.
• If the bags don't have an autoclave indicator section, cover the bag's biohazard symbol with autoclave indicator tape. Order tape from STORE, part number 7497.
• Autoclave the load immediately after preparation. Never leave items in the autoclave overnight.

Biohazardous waste red bag with biohazard symbol

• Read How to Dispose of Sharps for detailed instructions on how to package and label sharps in a red biohazardous sharps box.
• Cover the container's biohazard symbol with autoclave indicator tape. Order tape from STORE, part number 7497.
• Autoclave the load immediately after preparation. Never leave items in the autoclave overnight.

Sharps box with biohazard symbol

Sharps are devices or objects with corners, edges, or projections capable of cutting or piercing skin or regular waste bags.

• Polypropylene or stainless steels tubs are typically used for secondary containment.
• Make sure your plastic container is suitable for autoclaving. Not all plastics can be autoclaved. Plastic types can be identified by looking for initials imprinted on the container bottom.
  • Use:
    • Polypropylene (PP, recycle #5)
    • Polycarbonate (PC, recycle #unavailable)
  • Do not use:
    • Polyethylene (PE, recycle #1)
    • High-density polyethylene (HDPE, recycle #2)
  • If you're unsure about a new container, place it in an autoclave-safe container the first time.
    See Nalgene Labware's Autoclaving Web page for additional plastic considerations.
• Examine containers for cracks, which may cause autoclaved biohazard waste to fall onto the operator.
• Select a container with the lowest sides and widest diameter possible for the autoclave.
• Leave space between items to allow steam circulation.

• Temperature: Decontamination requires temperatures of at least 250–255°F (121–124°C). The chamber should reach 90% of its full temperature within 5 minutes.
• Time: The autoclave should run for at least 60 minutes.
• If the running time or the temperature is incorrect, rerun the load. If the autoclave fails to maintain the correct time or temperature again, contact Facilities Management, (858) 534-2930.

• Select the liquid cycle (also called "slow exhaust" on some machines), as required by San Diego County regulations.
• Push the "start" button on the control panel to initiate the cycle.

Fill out the log while the autoclave is "charging," or starting.

Each machine must have an autoclave log (PDF) (Word) where the operator records the date, description of waste, and other details.

• Wear personal protection equipment:
  • Lab coat
  • Eye protection
  • Closed-toe shoes
  • Heat-resistant gloves to remove items, especially hot glassware
• Wait for the pressure gauge to drop to zero with zero time remaining before opening the door.
• Never open an autoclave set for "slow exhaust" until the cycle is complete. Superheated liquids can boil over and damage the autoclave and injure the operator.
• Open the door cautiously. Stand behind the door and slowly open it. Allow all steam to escape before reaching inside.
• Let liquids stand another 10–20 minutes after the autoclave is opened to avoid any movement that could cause them to boil. Remove items carefully.

• Remove autoclaved waste immediately after the cycle is completed and the appropriate waiting time for liquids has been observed. Never leave items in an autoclave overnight.
• Place the autoclaved waste in your department's designated biohazardous waste collection area to be hauled for disposal. Ask your lab manager for instructions.

Dispose of autoclaved waste as medical solid waste.