Autoclaves

An autoclave is a sealed pressure chamber used to sterilize equipment and supplies by exposing them to high-pressure saturated steam. The combination of heat, moisture, and pressure kills microorganisms, including bacteria, viruses, fungi, and spores. Typical sterilization cycles operate at about 121°C (250°F) under 15 to 20 minutes, with shorter or higher-temperature cycles available for heat-tolerant materials. Some liquids require vented cycles to avoid boiling over or distorting containers.

Moist heat sterilization denatures proteins and disrupts cellular membranes. The pressure raises the boiling point of water, enabling steam to penetrate packaging and porous goods. Sterilization effectiveness is monitored with indicators and validated against standards; biological indicators using heat-resistant spores (Geobacillus stearothermophilus) are often employed to verify the process.

Autoclaves come in several configurations. Gravity-displacement models rely on gravity to push air out of the chamber, while pre-vacuum or high-efficiency models remove air to improve steam contact with wrapped loads. They range from compact tabletop units for clinics and laboratories to large industrial units used in pharmaceutical and hospital settings. Many units include built-in drying cycles, programmable cycles, and safety interlocks.

Applications include sterilizing surgical instruments, laboratory glassware, media and reagents, dental instruments, and some industrial materials. Load considerations affect cycle selection and packaging; plastics and certain textiles may require lower temperatures or shorter exposures to avoid deformation. Packaging materials must be permeable to steam and moisture-resistant.

Operation and maintenance require attention to safety and calibration. Operators should use appropriate PPE to handle hot containers and steam. Regular maintenance includes gasket inspection, chamber cleaning, and periodic calibration of temperature and pressure sensors. Validation and routine monitoring are guided by standards and accreditation schemes, such as ISO 17665 and related pharmacopoeia requirements.