• An autoclave is a device to sterilize equipment and supplies by subjecting them to high pressure steam at 121° C or more. It was invented by Charles Chamberland in 1879,although a precursor known as the steam digester was created by Denis Papin in 1679. The term autoclave is also used to describe an industrial machine in which elevated temperature and pressure are used in processing materials.

What can be autoclaved

  • Surgical Instruments
  • Glassware
  • Plastic tubes and pipette tips
  • Solutions and water
  • Animal food and bedding
  • Waste


  • Be sure the autoclave is functioning properly before use
  • Record information in User Log
  • Close door properly and securely
  • Choose the correct conditions for your material
  • For decontamination:
  • Temperatures between 121-124°C
  • Total processing time 60-120 minutes
  • Exposure time greater than 20 minutes
  • Pressure minimum 15 PSI

General Guidelines for Routine Maintenance of Autoclaves

  • Daily: Remove the outlet screen and clean with detergent and a brush under running water.
  • Clean the chamber using a cloth. Do not use abrasive cleansers or steel wool, as these will scratch the surface and increase corrosion.
  • Clean the door or lid gaskets with a cloth and check for defects. Replace defective gaskets.
  • Clean the shelves in the autoclave or the basket or cart that holds packs (including the wheels of the cart) with detergent and a cloth.
  • Weekly: Check the manufacturer’s instructions for maintenance of the exhaust line. If the instructions are unavailable, flush the exhaust line or chamber drain to keep it free of material that may interfere with air and steam leaving the chamber as follows:
  • Remove the outlet screen.
  • Pour 1 liter of detergent and hot water solution down the drain with a funnel.
  • Pour 1 liter of hot water down the drain to rinse out the detergent solution.
  • Replace the screen.

Maintenance Schedules

  • Part 4 of the British Standard outlines the following as minimum maintenance routines for laboratory autoclaves:
  1. Minimum daily maintenance schedule
  2. Minimum weekly maintenance schedule
  3. Minimum quarterly maintenance schedule
  4. Minimum annual maintenance schedule and inspection

Documentation of maintenance work

  • The following documents should be available:
  1.  Instruction Manual
  2.  Maintenance Log
  3.  Autoclave Process Record
  4.  Permit to Work Certificates


  • Validation of the Autoclave is classified into the following
  1.  IQ  _Installation Qualification
  2.  OQ – Operational Qualification
  3.  PQ – Performance Qualification


Insallation Qualification:

  • Name
  • Description
  • Model and identification no.
  • The location
  • Utility requirements
  • Connections and safety features of the systems/equipment which need to be documented.




  • To demonstrate and document that the operations
  • of the Autoclave take place as specified .

2.0 SCOPE :

  • Autoclave xxxxx will be qualified to meet OQ.


  • Microbiologist, Manager Q.C


  • This should be performed by external agency like IIME.

4.1 Verify the following as per instrument operating procedure and calibration certificate kept in place before validation.

4.1.1 : Temperature display of Autoclave.

4.1.2 : Compound pressure gauge of Autoclave.

  • Acceptance criteria :
  • All calibration data found to be within the acceptable norms of calibration certificate.

4.2 Calibration of Thermocouples :

  • Calibrate all the thermocouples of data logger before and after the validation using standard thermometer and also made available party’s calibration certificates.
  • Acceptance criteria:
  • The variation between the temperature of thermocouples and the standard thermometer found to be within the acceptance criteria.

4.3 Heat Distribution Studies

  • Carry out heat distribution studies by using a multi-point data logger and maintain holding time for 15 minutes at 15 lbs. by fixing all the 12 probes as per diagram-1. Record the temperature and lag time of each probe as per Annexure –1 & 2.
  • Acceptance criteria
  • All probes must reach temperature 121-124°C and pressure must be within 15 to 18 lbs for 15min cycle.
  • Diagram-1 Probe to 12 inside the chamber


  • Load Pattern
  • Maximum Load
  • Load with all the glassware and media filled upto 70%, of the chamber and the details are as follows.
  • Test-1 : 250ml Conical flasks = 12 Nos with media, 13 Nos without media, 500ml Conical flasks with media = 4nos, 1000ml Conical flasks with media =4nos, Pipette10ml=10nos,Pipette 2ml=10nos, Pipette 5ml=10nos, Pipette 1ml = 10nos,100ml
  • bottles=20nos ,Filtering unit=10nos, Test tubes =25nos
  • Minimum Load
  • Load with all the glassware and media required for a day’s analysis (average).
  • 250ml Conical flasks with media = 6nos, 500ml Conical flask with media – 3 nos., 1000ml Conical flask – 1 Pipette 10ml= 10nos, Pipette 2ml= 10nos, Pipette 5ml= 10nos, Pipette 1ml=10nos, Bottles=10nos, Test tubes – 25nos.
  • Record the temperature and lag time




  • To provide a performance qualification protocol for Autoclave.

2.0 SCOPE :

  • Specified to Autoclave xxxxx.


  • Microbiologist, Manager Q.C


4.1 Heat Penetration Studies: Carry out the heat penetration studies by using a multi point data logger for the following loads mentioned. Record the temperature and lag time.


  • Acceptance criteria:
  • All 12 probes must reach temperature 121°C to 124°C and pressure must be within 15 to 18 lbs. for 15 min cycle.

4.2 Microbial limit test :

  • Incubate the sterilised media flask or tubes from any one Maximum and Minimum load of heat penetration studies and observe for nutritive properties. Bacteria: 30 – 35 °C for 72 hrs, Fungi : 20 – 25°C for 120 hrs
  • Acceptance criteria:
  • No microbial growth should be observed i.e. Negative control and Nutritive properties of media must pass

4.3 Microbial challenge test :

  • Keep ampoules containing spores suspension of Bacillus stearothermophilus 106 population at various location of the autoclave along with probes and maintain the sterilisation temperature at 15psi and 121°C during the heat penetration studies, once on the maximum load.
  • Acceptance criteria:
  • Autoclaved ampoules containing Bacillus stearothermophilus spores suspension ampoules should not show any colour change after five days of incubation.AUTOCLAVE



  • Master Instrument used for validation of autoclave
  • Institutes name and address carrying out calibration.
  • Standard calibrating instrument name and number.
  • Instrument certified against (Instrument of national or international standards)
  • Date of calibration and validity period of calibration.
  • Training certificate of persons (External agency) carrying out validation.

6.2 Autoclave being calibrated :

  • All temperature readings for autoclave being validated should be collected from the approved external agency like IIME.
  • Validation report with observed any error, statement of calibration and next validation due.


  • Once in a year until and unless no change in autoclave. In case of any change, the autoclave must be revalidated


  • CONCLUSION : Finally conclusion should be drawn based on the results of above tests and documented