LimsPulse
Microbiology & sterility

Autoclave (steam steriliser)

Kills microorganisms, including bacterial spores, with saturated steam under pressure. Used in the QC microbiology lab to sterilise culture media, glassware and equipment, and to decontaminate used media before disposal.

  • Pharmaceutical
  • Biotech
  • Hospitals
  • Food & beverage
  • Research laboratories
  • Medical devices
Photo of a Autoclave (steam steriliser)
Photo: Nadina Wiórkiewicz (Nadine90), CC BY-SA 3.0 (cropped), via Wikimedia Commons
Follow your site SOP
This is a typical operating sequence for learning. Your instrument model and approved SOP take precedence.
STAGE 1

Before you start

  1. 1Check the autoclave is within its validation, calibration and statutory inspection dates and has no 'out of order' label.
  2. 2Check the water level in the steam generator and that the drain strainer is clean.
  3. 3For pre-vacuum autoclaves, run the warm-up cycle and the daily Bowie-Dick (air removal) test and record the result before any load.
  4. 4Confirm which validated cycle and load pattern you will use for the items to be sterilised.
  • Never mix clean items to be sterilised with used cultures or waste in the same load.
STAGE 2

Loading

  1. 1Arrange items exactly as in the validated load pattern, leaving space between them for steam to circulate.
  2. 2Loosen caps on bottles and fill media containers to no more than about two-thirds of their volume.
  3. 3Cover open glassware with aluminium foil or use vented closures; place wrapped items on their edge, not stacked flat.
  4. 4Stick autoclave indicator tape on each item or basket, and place the load probe in the reference container if the cycle uses one.
  5. 5Close and lock the door and check the door seal indicator.
  • Tightly closed bottles can burst under pressure. Overfilled flasks can boil over during exhaust.
STAGE 3

Running the cycle

  1. 1Select the validated cycle (e.g. 'Media 121 °C / 15 min' or 'Liquids') and start it.
  2. 2Watch that the chamber reaches the set temperature and that pressure agrees with the steam table for that temperature.
  3. 3Do not interrupt the cycle. If an alarm or cycle failure occurs, treat the load as not sterile.
  • Never try to open the door or override the interlock during a cycle.
STAGE 4

Unloading and release

  1. 1Wait until the chamber pressure has returned to zero and the load temperature is below the safe limit (often about 80 °C for liquids) before opening.
  2. 2Open the door slightly and stand behind it to let residual steam escape.
  3. 3Wear heat-resistant gloves, face shield and apron to remove the load.
  4. 4Check the indicator tape colour change and review the cycle printout against the set parameters.
  5. 5Sign the autoclave log with cycle number, load description and result, and label the load as sterilised.
  • Superheated liquids can boil violently when moved or opened. Let them cool before handling.
In LimsPulse · Calibration Management

Keep every Autoclave in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how