Sterilization by autoclave, its principle, procedures, application and precautions.


Sterilization by using autoclave.


Sterilization is the process of removal or killing of microorganisms from the object. In the laboratory it is done by the use of an instrument, the autoclave.

Autoclave is a cylindrical vessels having double wall around all parts except the upper side. It builts to withstand the steam pressure of at least 15 LBS per square inch.

The principle used here is saturated steam under pressure. Saturated steam is the water vapour at the temperature saturated steam is the water vapour at the temperature at which it is produced.

The water molecules become more aggregated that increase their penetrating power. Autoclave is usually operated at 15 LBS per square inch pressure for 15 minute which raises the temperature to 121°C.


  • Sufficient amount of water is placed inside the autoclave.
  • Pack the material properly before putting inside the autoclave for sterilization.
  • The steam outlet is kept open till  air from inside autoclave has been evacuated and then close the steam outlet.
  • The  pressure is allowed to remain at 15 LBS per square inch for 15 to 30 minute is done by controlling the steam.
  • Now, off the plug leave the autoclave for cooling down and thus the pressure is reached down to zero mark.
  • Then open the lid and take out the materials.


  • Autoclave used to sterilize usual  non- carbohydrate media, broth and agar media, contaminated media ,etc.
  • This type of sterilization is also used in the commercial canning of fruits and vegetable.
  • In, Hospital Also to maintain hygiene and contamination free clothes and instruments.


  • Ensure there is sufficient water in the autoclave before operating .
  • The lid should be closed tightly.
  • The air should be completely evacuated from the autoclave and the steam must have to material to be sterilized.