In a common steam sterilization cycle, what is the typical pressure used (in psi)?

• A. 5 psi
• B. 10 psi
• C. 15 psi
• D. 20 psi

Answer: (C)

Steam sterilization relies on moist heat to destroy microorganisms. The temperature of saturated steam is determined by its pressure: higher pressure means higher temperature. In common autoclave practice, the standard target is 121°C, which is achieved with about 15 psi of gauge pressure. This combination—121°C for a defined exposure time—provides reliable sterilization for a wide range of materials.

Lower pressures (like 5 or 10 psi) would yield lower temperatures and may not inactivate all spores promptly, while higher pressures (around 20 psi) raise the temperature further but aren’t the typical default cycle and can risk damage to sensitive items. So the typical pressure used is 15 psi.