How Does a Laboratory Autoclave Work?

An autoclave, or steam sterilizer, destroys microorganisms and bacterial spores via high temperatures and pressure. It has a large steel chamber, a discharge tap for air and steam, and a safety valve. The process starts by replacing most of the air in the chamber with steam. The steam then displaces the air and creates a vacuum.


Steam sterilization is a standard decontaminating liquid handling device and laboratory equipment method. The process involves exposing the material to saturated steam at a specified temperature and pressure for a limited time, usually 30-60 minutes. Autoclaves for tattoo shops have a controller interface opening and closing valves in a predetermined sequence. The cycle usually begins with a vacuum stage, which removes the air and increases pressure in the chamber to a set level. Once the pressure and temperature have reached a set point, the sterilizer drain is closed. Steam enters the top of the chamber. As the steam travels inside, it pushes out all the air trapped in the chamber. Depending on the type of items being sterilized, the cycle may include a heat or cold process. Both cycles involve exposure to saturated steam at a temperature of 121degC (250degF) or 132degC (270degF) for a period required by the manufacturer.


An autoclave for salons uses heat to kill bacteria and other microorganisms on objects. It works by heating the items to an appropriate temperature for a set time and then placing them in a pressure vessel that contains steam. The sterilization process can take a few minutes to complete, but it depends on the type of load and the desired Sterility Assurance Level (SAL). Once sterile, a backpack is considered decontaminated. Some laboratory autoclaves also use chemical indicators, such as tape that changes color or displays diagonal stripes, to ensure the load is sterilized correctly and no longer contaminated. However, these indicators should be placed on the exterior of the load and not directly inside it. Research-grade laboratory autoclaves are used to sterilize glassware, utensils, and culture media in education, biomedical research, pharmaceutical research, and industrial settings. These models often have unique features like vacuum functions, special cycles, and integral electric boilers.


Pressure is the leading way that an autoclave sterilizes lab materials. This process involves saturated steam under high pressure for a specified period at a specific temperature to kill microorganisms. The procedure in an autoclave begins by boiling water to generate steam that enters the chamber. This steam displaces air in the room using a vacuum system seen in larger autoclaves or by displacement (an option found in smaller tabletop models). Once all the air is removed, the chamber’s drain closes, and the cycle increases pressure and temperature. Sterilization cycles typically have four stages. In the first stage, the pressure inside the chamber increases to a higher level than the ambient pressure. Next, the temperature is raised to the desired level and held at that level for a specific period. In the final stage, the pressure is released from the chamber through an exhaust valve, and the interior is returned to the ambient level.


Chemicals are substances that humans create or use in a variety of ways. They’re found in the natural world and on our bodies — and they can be harmful to people and the planet if we don’t handle them correctly.

Steam and high-pressure heat devices are inside the chamber in a laboratory autoclave. It’s essential to understand how the autoclave works so you can make sure your equipment is adequately sterilized.

The temperature and pressure rise in the autoclave until a set point is reached, usually 121 degrees Celsius and 15 pounds per square inch gauge pressure (psig). Once this is achieved, the exhaust valve closes so the heat can remain in the device and kill microorganisms. The autoclave is left at this temperature for the required amount of time.