An autoclave is used in medical and laboratory settings to sterilize lab equipment and waste. Autoclave sterilization works by using heat to kill microorganisms such as bacteria and spores. The heat is delivered by pressurized steam. Pressurization allows the steam to reach the high temperatures that are required for sterilization.
According to Centers for Disease Control (CDC) Guidelines for Disinfection and Sterilization of Healthcare Facilities, pressurized steam is the most widely used and dependable method of sterilization. It’s nontoxic and inexpensive, it kills microbes and spores rapidly, and it quickly heats and penetrates fabrics.
According to manufacturer Tuttnauer, medical clinics and dental offices typically use tabletop autoclaves, which are about the size of a microwave oven, while hospitals use much larger units that can sterilize many instruments at once.
To work effectively, an autoclave must remove all the air in and around the object that’s being sterilized, forcing steam to penetrate its surfaces, according to Healthcare Purchasing News. There are two basic ways that an autoclave can remove the air and force in steam:
- Gravity displacement autoclaves, also called gravity autoclaves, inject steam into the autoclave chamber and then rely on that steam, which is heavier than air, to force the air to leave the chamber through the drain vent at the bottom, according to the CDC.
- Prevacuum or prevac autoclaves use a vacuum pump to remove air from the chamber before steam is admitted to it, which means that steam penetrates even porous objects almost instantly.
What Type of Autoclave Do I Need?
Gravity autoclaves have a simpler design and are recommended for most uses, according to manufacturer TOMY. They are suitable for common laboratory media including type I borosilicate glassware or other autoclavable labware, steel lab utensils, and biohazardous waste. On the other hand, prevac autoclaves are more effective at sterilizing objects that are large or porous, including wrapped objects such as surgical kits; objects made from high-density polyethylene, such as pipette tips and syringes; and animal cages and bedding.