Autoclaves provide a physical method for disinfection and sterilization. They work with a combination of steam, pressure and time. Autoclaves operate at high temperature and pressure to kill microorganisms and spores. Autoclave Sterilizers are used to decontaminate some biological waste and sterilize the means, tools and laboratory ware. Regulated medical waste that may contain bacteria, viruses and other biological materials is recommended to be inactive by autoclaving before disposal.

An autoclave is used to sterilize surgical equipment, laboratory tools, pharmaceuticals and other materials. It can sterilize solids, liquids, cables and instruments of various shapes and sizes. Autoclaves vary in size, shape and functionality. A very basic autoclave is similar to a pressure cooker; both use steam power to kill bacteria, spores and germs resistant to boiling water and powerful detergents.

Autoclaves use pressurized steam as their sterilization agent. The basic concept of an autoclave is to have each item sterilized -whether it is a liquid, plastic ware, or glassware- come in direct contact with steam at a specific temperature and pressure for a specific amount of time. Time, steam, temperature, and pressure are the four main parameters required for a successful sterilization using an autoclave.

The amount of time and temperature required for sterilization depends on the type of material being autoclaved. Using higher temperatures for sterilization requires shorter times. The most common temperatures used are 121 C and 132 C. In order for steam to reach these high temperatures, steam has to be pumped into the chamber at a pressure higher than normal atmospheric pressure.

Now that we have covered the basic principle of how autoclaves use pressurized steam to sterilize contaminated materials, we will now go over how autoclaves operate.

Pressure and temperature affect boiling. Water boils when the water molecules contains enough energy to escape the liquid and form water vapor or what is called steam above it. As the water gets hotter, water molecules contain more energy and can more easily escape the liquid. On the other hand, pressure is important as well. The higher the pressure above the water, the more difficult it is for the water molecules to break free of the liquid and vice versa.

Consider going up in altitude. The higher you go, the lower the atmospheric pressure. Boiling water at this higher elevation occurs at a lower temperature because it takes less heat to boil the water. It is much easier for liquid water to go into water vapor because the pressure above the liquid is much less. In fact, if you were on top of Mount Everest, water boils at around 70°C not 100°C.

The boiling point of water at one atmosphere (sea level, 760mmHg) is 100°C. Raising or lowering the pressure by around 28mmHg changes the boiling point by 1 degree C.

An autoclave chamber sterilizes medical or laboratory instruments by heating them above boiling point. Most clinics have tabletop autoclaves, similar in size to microwave ovens. Hospitals use large autoclaves, also called horizontal autoclaves. They’re usually located in the the Central Sterile Services Department CSSD) and can process numerous surgical instruments in a single sterilization cycle, meeting the ongoing demand for sterile equipment in operating rooms and emergency wards.

They are important in tattoo shops, beauty and barber shops, dentist offices, veterinarians and many other fields.