How Does an Autoclave Work?


  • The most common purpose of an autoclave is to sterilize equipment used on humans and animals. Doctors, dentists and veterinarians are the most common users because they must use sterile instruments when performing medical and surgical procedures to protect their patients. Otherwise, contamination on the instruments may cause an infection. Body piercing providers also use this sterilization method because they use tools that puncture the skin. The autoclave works by completely removing bacteria and other contaminants from the tools and instruments.

Air Removal

  • The first step in the autoclave process is totally removing all of the air in the autoclave chamber. The chamber is sealed, and all of the air is removed through a vacuum pump, steam pumping or steam pulsing. The air may also be forced out through downward displacement, using steam to force it downwards. The exact method varies, depending on the model of autoclave being used.


  • Once the air has been totally removed from the unit, the tools or instruments are sterilized by exposure to heat. The sterilization cycle typically runs anywhere from 3 to 18 minutes, and the heat level is usually set between 121 and 134 degrees Celsius. The intense heat kills bacteria, viruses and other organisms. The autoclave works best when the items are place inside in an arrangement that allows the heat to circulate completely.


  • An autoclave will not work to sterilize some items, such as certain plastics, because they can be melted or damaged by exposure to intense heat.