Autoclaves are used for steam sterilization. A distinction is made between autoclaves intended for sterilizing liquid media and those intended for sterilizing solids. These are used in the medical field. They allow alternating vacuum phases with overpressure phases. There are 3 classes according to the type of material to be sterilized: B, to sterilize solid, hollow, porous medical devices, packaged or not, S, to sterilize solid medical devices, packaged or not, and N to sterilize only solid medical devices unwrapped.