Autoclave Guidelines

Autoclaves are a convenient and reliable tool for sterilization of biohazardous waste, equipment, media, and more. See below for guidelines regarding safety, usage logs, efficacy monitoring, waste disposal, and suggested cycles.

Autoclave Safety

Important: Do not autoclave items containing corrosives, solvents, volatiles, or radioactive materials.

Prior to loading

  • Before using the autoclave, check inside the autoclave chamber for any items left by previous users that could pose a hazard.
  • Ensure that the drain strainer is clean before loading the autoclave.
  • Ensure that the door gaskets have not deteriorated, but are still intact and pliable.

Loading the autoclave

  • Load the autoclave as per the manufacturer’s recommendation. DO NOT overload the autoclave.
  • Tie bags loosely to allow for steam penetration.
  • Individual glassware pieces should be placed in a heat resistant plastic tray on a shelf or rack, and never placed directly on the autoclave chamber bottom or floor.
  • Make sure that the door of the autoclave is fully closed and latched and ensure that the correct cycle for the items being autoclaved has been selected before starting the cycle.

Opening the autoclave

  • Wear the proper PPE, including heat resistant gloves, rubber apron for liquids, eye protection (or face shield for liquids), and closed-toe shoes.
  • If handling sharps (e.g. broken glass), use tongs or ensure gloves are cut-resistant.
  • Open the door slowly. Keep your head, face and hands away from the opening.
  • Allow materials inside the autoclave to cool for at least 10 minutes with the door open before unloading the autoclave. Removing contents too soon may cause heat stress and fracturing of materials, especially glass.

Autoclaving Liquids

  • To prevent bottles from shattering during pressurization and heating, the caps of containers with liquids must be loosened before loading.
  • Use only borosilicate glass (Pyrex™ or Kimax™) which can withstand the high autoclave temperatures.
  • Use a heat resistant “autoclave” tray with a solid bottom and walls to contain the contents and catch spills.
  • Liquids should be within a heat resistant plastic tray containing an inch of water, to ensure even heating.
  • Bottles of liquid should not be more than 2/3 full.
  • Keep 1-2 inches of space between bottles.
  • After unloading from the autoclave, let the liquids cool for at least a full hour before touching with ungloved hands. Be sure to let others in the area know that a heat hazard is present.

Autoclaving Dry Loads

  • Add ¼ to ½ inch of water to the tray so that the contents will heat evenly.
  • Check plastic materials to ensure that they are compatible with being autoclaved. For example, polyethylene plastics (LDPE and HDPE) cannot be autoclaved.
    After unloading from the autoclave, let the materials cool for a minimum of 15 minutes before touching with ungloved hands.

Autoclave Use Logs

When an autoclave is used to sterilize biological waste, the cycle must be recorded on an Autoclave Use Log. All fields (date, treatment conditions, weight, and user name) must be completed. Completed autoclave use logs must be retained by laboratory staff for 3 years. Autoclave record keeping will be confirmed during yearly laboratory safety surveys.

Efficacy Monitoring

TCEQ Regulations require that autoclaves used to sterilize biohazardous waste must be monitored routinely for efficacy. Efficacy monitoring will be performed on a monthly basis by EHS, using a biological indicator system. 

Disposal of Autoclaved Waste

After cycle completion and cooling, the orange bag shall be placed inside a secondary opaque trash bag, and the secondary trash bag shall be sealed. An “Autoclaved” sticker shall be attached to the secondary opaque trash bag. Fill out the date on the sticker. Stickers can be obtained from EHS. The autoclaved waste may now be placed in the regular trash.

Sterilization Cycles

Cycle Description Application
 Gravity







  Steam displaces air in the chamber by gravity  Glassware, unwrapped goods, utensils, tips
 Vacuum  Air is mechanically removed from the chamber and load. This allows the steam to penetrate porous areas of the load. Wrapped goods, animal cage bedding, porous materials, red bags
 Liquids  A gravity cycle with a slower exhaust rate to minimize boiling over.  Media, water, etc.