What Are Autoclaves?

Autoclaves are pieces of laboratory or manufacturing equipment designed to generate high-temperature steam under pressure. Although there are a number of industrial uses for autoclaves, they are most widely seen in clinical and research laboratory settings where they are used to sterilize medical instruments and laboratory equipment.

What is Sterilization?

• Most of the surfaces we encounter on a daily basis contain a variety of microorganisms. Few are harmful to healthy humans, so in most situations it is acceptable for surfaces to simply be clean, meaning that there is no visible soiling or debris. In food preparation areas and other special environments it is necessary for surfaces to be sanitized, which means that microorganisms are reduced to acceptable levels by chemical or other processes. For medical and laboratory purposes, surfaces must be completely sterile, which means all microorganisms have been killed.

How Autoclaves Work

• Before the invention of the autoclave in the late 19th century, medical instruments were sterilized by immersion in boiling water. Unfortunately, some microorganisms can survive this process, so higher temperatures were required. Steam is an ideal medium for this, requiring lower temperatures and shorter times than dry heat. The steam is pressurized in an autoclave to permit temperatures higher than the boiling temperature of water, typically 250 degrees Fahrenheit or 120 Celsius, for fifteen minutes. This is sufficient to kill even heat-tolerant microorganisms.

Uses of Autoclaves

• Autoclaves are widely used in medicine, especially in relationship to surgery, to sterilize instruments and implements before they are reused or discarded. Forceps and other instruments are built for ongoing use, but the rise of disposable scalpels and syringes has made their reuse uncommon in surgery, They are still sterilized in autoclaves before disposal, to eliminate potential bio-hazards. In a laboratory setting, autoclaves are used to sterilize a wide range of equipment and glassware, or even dishes of a culture medium.

Autoclave Precautions

• It is important for the technician who loads the autoclave to space its contents properly, so that the steam has unobstructed access to all surfaces. It is also crucial to monitor the operating temperature of the autoclave to ensure it has done its job. Some models have external gauges or digital readouts, while others are tested by means of a disposable strip of adhesive, which changes color to show the correct temperature has been reached. Autoclaves have the potential for explosive decompression, and must be carefully maintained in order to avoid unnecessary danger to staff.