Sterilizing equipment uses either steam or air pressure to sterilize tools. Air is circulated through heat exchangers until the air reaches a specific temperature for a certain amount of time. The product is then cooled with water. There is also dry heat sterilization which uses dry heat to sterilize things like liquids or powder medications, bottles, and production equipment. An autoclave uses a pressure chamber and saturated steam to sterilize objects. All air must be removed from an autoclave before its process can be performed.