Sterilization is any method that efficiently destroys or removes transmissible species, including bacteria, spores, and viruses. Sterilization methods come in a variety of forms, including autoclave sterilization.

Sterilization Using An Autoclave 

What is an autoclave? Autoclaves, commonly known as steam sterilizers, are often utilized in medical and industrial settings. These are devices that kill dangerous microbes, pathogens, fungus, and spores on objects that are put within a vacuum vessel using high-pressure steam.

The objects are processed at a sterilization temperature and kept there for a set period of time. The vapor in the steam effectively passes heat to the objects, destroying bacteria and germs. Autoclave sterilization or autoclaving is the most efficient way of sterilizing laboratory instruments to eliminate dangerous microorganisms, especially those used to handle liquids.

Types Of Autoclaves 

Autoclaves sterilize mainly using gravity or vacuum-induced processes, and some types incorporate both techniques. The gravity-displacement type is perhaps the most popular type of autoclave. Here’s how the two most popular autoclave types work and how they differ from each other:

  • Gravity-Displacement Autoclave 

Gravity-displacement autoclaving is the simplest method and is ideal for sterilizing the majority of laboratory instruments made of steel and glass. It’s also used in the treatment of biohazardous material.

Gravity autoclaving entails injecting steam into the cavity of the vessel. This process disperses and drives atmospheric air out of exhaust valves, allowing excess steam for complete disinfection. This system lends its popularity due to its simple design and independence from external systems to expel atmospheric air with steam, rendering this type of autoclave more economical and reliable. 

  • Vacuum Autoclave

Vacuum autoclaving is more adapted for conditions in which air can’t be readily separated from sterilization materials. This may cover big or porous objects, including livestock crates, beds, and also individually packaged surgical tools. The vacuum mechanism permits for more thorough sterilization by fully evacuating the atmospheric air inside, enabling hot steam to infiltrate and disinfect spaces that would usually be filled by air. 

How Does An Autoclave Works? 

Regardless of the type of autoclave, these machines work in the same principle. Sterilization implements are mounted within a pressure compartment, often known as a chamber. Three variables are important for efficient autoclave sterilization—duration, temperature, and steam performance.

To satisfy these standards, the autoclave system is divided into three stages: 

  • Conditioning Stage: Since air affects effective sterilization, this is eliminated from the pressure compartment. This is done during the conditioning stage. Steam circulates into the autoclave, dislodging the air inside the chamber.
  • Exposure Stage: Once the air has been expelled from the chamber, the sterilizer drainage shuts, and steam is continually released into the vessel. This process quickly raises the internal pressure and temperature to a fixed value until the target duration is achieved. 
  • Exhaust Stage: This is the last stage of operation where the drain is released and the steam is expelled, which depressurizes the chamber and allows materials inside to dry. 

Following the standard, autoclave sterilization may penetrate even the tiniest nooks and crannies and eliminate microbes, waste, and fungi, rendering the sterilized materials completely clean and available for use.

Pros Of Autoclave Sterilization 

With the emergence of new sterilization technologies, it’s critical to choose the most efficient method possible. Steam sterilization is both efficient and simple to do, making it an excellent alternative for a wide range of applications. Furthermore, here are five advantages of autoclaving and why it’s the preferred method used in sterilization:

  • Effective For Killing A Variety Of Microorganisms 

Among the most efficient methods of transferring thermal energy is by humidity found in steam. Owing to its capacity to infiltrate bacterial cells using steam, autoclaving has been shown to be more efficient at destroying a wide variety of microorganisms than sterilization by dry heat. 

Because of increased pressure and steam production inside an autoclave, the temperature inside the vessel may be raised above 100°C. This process enables the eradication of a wider variety of bacteria and other microbes. 

  • Safe Method Of Sterilizing

In comparison with other sterilization methods, autoclaving is nontoxic. Because steam is a kind of vapor that is formed when water is boiled, it effectively is water but in a different state of matter. Even so, care should still be exercised to avoid being burned by hot steam.

Since steam that comes from boiling water requires no additional chemicals, it reduces the need for using dangerous chemicals. Autoclaving, therefore, is safer because it easily eliminates bacteria and other pathogens while still being a relatively safe procedure to use.

  • Rapid Cycle Time 

Steam is quicker at killing bacteria compared to dry heat, owing to its greater ability to transport heat over other mediums and over a wider range. For instance, dry heat sterilization usually requires two hours at a constant temperature of 160°C to destroy pathogens and spores found in any material.

Comparatively, steam kills most bacteria within five minutes at 134°C due to the denaturation of the microbial proteins. This goes to show that autoclaving takes less time than dry heat in eliminating microorganisms.

  • Cost-Effective Method

Steam is easily accessible due to the fact that it only needs two things—water and heat. Given that almost all facilities or laboratories require a source of water, obtaining water to operate the autoclave is fairly possible. 

Along with being readily usable, steam is often cost-efficient. Because autoclaves don’t need any other chemicals, operating it is reasonably affordable. This makes it the most economical method of sterilization.

  • Better Than Chemicals 

Chemical sterilizers used in clinical practice may address a variety of microorganisms, but they can’t completely degrade or kills spores, which are microorganisms that have been shown to be immune to some sterilization methods.

Eliminating spores is more complex than removing other strains of microbes since spores can withstand high temperatures. Spores may be eliminated using a kind of steam sterilization, which is also known as autoclaving. 


The most commonly used and reliable system for sterilization is by using steam through an autoclave. It’s non-toxic and cheap. Autoclaving is effective since it rapidly eliminates a wide range of pathogens, even long-lived and resistant spores. It’s also worth mentioning that autoclaving is the most efficient sterilization method device for surgical equipment, other industrial materials, and scientific apparatuses.

Infographic provided by Technical Safety Services, cleanroom testing and certification

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