What Is an Isothermal Autoclave?

Isothermal autoclaves are common devices in labs and health care settings. They are used to sterilize equipment and decontaminate waste--precautions that are especially important when dealing with contaminated materials such as animal bedding, lab glassware and surgical instruments.

Types

There are three types of autoclaves: gravity, isothermal and prevacuum. Some autoclaves have multiple settings so that you can choose any of these options.

Function

In all autoclaves, the items to be sterilized are placed in polypropylene bags or steel pans and loaded into the chamber. The chamber fills with high-pressure, high-temperature steam, which destroys bacteria and other microorganisms. In a gravity autoclave, the steam enters from the top and compresses the air in the chamber, which drains out through the bottom. In a prevacuum type, air is sucked out before the steam is introduced, so that the chamber can fill with steam more rapidly. Isothermal means "same temperature"; in an isothermal autoclave, both the jacket (the space surrounding the chamber) and the chamber are filled with steam at the same time.

Considerations

An isothermal autoclave reaches a lower temperature than a gravity or a prevacuum device. It is more suitable for items that are heat-sensitive or might congeal. Gravity autoclaves are best for empty containers that are heat-stable, and prevacuum autoclaves are best for porous materials, such as used animal bedding.

References

• University of Windsor: Safe Operations of Autoclaves in the Treatment of Biomedical Waste
• University of Central Florida: Autoclaves Safe and Effective Use
• University of Maryland, Environmental Safety: Autoclaving Procedures