autoclave

An autoclave is a pressure chamber used to sterilize equipment and other objects by exposing them to saturated steam at high temperature. The sterilization relies on moist heat, which denatures proteins and destroys microorganisms more effectively than dry heat. Typical practice uses steam at about 121°C (250°F) under pressure, commonly around 15 pounds per square inch (psi), for 15 to 20 minutes, though higher temperatures (such as 134°C) can reduce cycle times.

There are several main designs. Gravity-displacement autoclaves release steam to displace air and are common in smaller facilities, while vacuum or pre-vacuum models use air removal and steam pulsing to achieve faster, more uniform heating. Autoclaves range from benchtop units to large industrial vessels and may include built-in steam generators or rely on a centralized supply.

Materials suitable for autoclaving include most metals, glassware, laboratory plastics that are autoclave-compatible, surgical instruments, culture media, and many textiles. Liquids are sterilized in containers that allow venting of steam and release of expanding air; unopened liquids may be vented briefly before sealing for storage. Not all items are autoclaveable—heat-sensitive plastics, some electronics, and porous materials may be damaged.

Operation typically involves loading, sealing, pressing the appropriate cycle, and allowing a drying phase for some instruments. Validation and quality control are essential and may include chemical indicators, biological indicators (for example, Bacillus stearothermophilus spores), and periodic tests such as Bowie-Dick for pre-vacuum systems.

Historically, autoclaves were developed in the late 19th century and have become standard equipment in medicine, microbiology, pharmaceuticals, and industry for reliable sterilization. Safety features include interlocked doors, pressure relief systems, and regular maintenance and testing to ensure effective sterilization.