Calibration of steam sterilizer (Autoclave)

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Calibration of Autoclave by Biological Indicator:

  • Put five indicators of Bacillus steriothermophilus spores at five different locations in the chamber.
  • Run Autoclave at 121°C & 15 lbs pressure for 15 minutes.
  • After completion of sterilisation cycle remove biological indicators from autoclave.
  • Inoculate the biological indicator in sterile Soyabean casein digest medium tubes.
  • Inoculate an unsterilized indicator in sterile Soyabean casein digest tube as positive control and incubate one sterile Soyabean casein digest medium tube without any inoculation as negative control.
  • Incubate all the tubes at 55° to 60° for 72 hours.
  • If purple colour changes to yellow after 15 to 18 hours: Sterilisation is faulty.
  • If purple colour changes to reddish brown after 72 hours: Material is overheated.
  • Incubate unopened Ampoules at 56° C for o72 hours if purple colour is retained after 72 hours of incubation.  Sterilisation is perfect.

Calibration of Autoclave by using Heat labile Physical Indicator:

  • lace five strips of steam clox at five different places in the chamber.
  • Run autoclave at 121°C & 15 lbs pressure for 15 minutes.
  • After completion of sterilization cycle remove the indicators from the autoclave.
  • Observe the colour changes in indicator.
  • The colour should change from pink to green.