Final answer:
In the conditioning phase of steam sterilizers, air is removed from the chamber and replaced with steam to achieve the high temperatures and pressures needed for sterilization.
Step-by-step explanation:
During the conditioning phase of steam sterilizers, also known as autoclaves, the air within the chamber is removed and replaced with steam. This is critical for achieving the necessary pressure and temperature conditions for sterilization. In gravity displacement autoclaves, steam is introduced from the top or sides, forcing the heavier air out through a vent. Alternatively, prevacuum sterilizers use a high-speed vacuum to entirely remove air before injecting steam, enabling better penetration through wrapped items. Steam must directly contact materials for effective sterilization, typically at 121 °C (or 132 °C) for 20 minutes at 15 to 20 psi. Containers remain loosely closed and instruments loosely wrapped to facilitate steam contact.