What is the proper pressure and temperature for sterilizing instruments in an autoclave?

• A. 300°F at 20 psi
• B. 250°F at 15 psi
• C. 180°F at 5 psi
• D. 212°F at 1 atm

Answer: (B)

Autoclave sterilization relies on moist steam under pressure, which raises the effective temperature and drives heat into instruments quickly to denature proteins and destroy microbes, including spores. The widely used and tested combination is 250°F (about 121°C) at 15 psi. This pairing ensures steam remains saturated and penetrates loads effectively, making the sterilization cycle reliable for most instrument configurations.

The other options either use temperatures or pressures that aren’t the standard sterilization condition, or rely on boiling at atmospheric pressure, which doesn’t achieve sterilization. For example, boiling water at 212°F under normal pressure isn’t sufficient to kill spores, and 180°F at 5 psi doesn’t reach a high enough temperature for reliable sterility. Higher temperatures at greater pressures exist, but the accepted practice for standard cycles is 250°F at 15 psi.