Autoclave or retort

The autoclave is a pressure chamber used for sterilization. This device was invented by Charles Chamberland in 1879. It utilizes steam under pressure to sterilize items placed within it. High pressure enables steam to reach a high temperature. Steam is one of the most effective carriers of heat. Therefore, steam becomes efficient in killing cells and coagulating proteins.

The common effective operating temperatures and pressures for autoclave is 115°C/10 pounds per square inch (psi), 121°C/15 psi, and 132°C/27 psi. The higher the temperature and pressure, the shorter the cycle time required for complete sterilization.

The autoclave remains a gold standard sterilization tool for processing items like steel surgical instruments and some heat resistant fabrics. Unfortunately, heat and moisture-sensitive objects can deform or melt under the extreme conditions, so alternatives such as ethylene oxide treatment and irradiation are used as deemed appropriate.

Figure 1. Diagram of an autoclave.

The autoclave will perform three basic phases:

• Heating phase: steam enters the sterilizer jacket, and the air is removed from the sterilizer chamber.
• Sterilization phase: Objects are exposed to steam at a set of temperature for a set time.
• Cool-down: returning the product to atmospheric pressure and drying the product.