An autoclave can be defined as an instrument used to clean any equipment and keep germs and bacteria-free.

It is used in Laboratories, data centers, research centers, pharmaceuticals giants, educational institutes, and different industries. The synonym for Autoclave is a “steam sterilizer.”

The only difference between these technologies is that Autoclave is widely used in laboratories, and sterilizer is commonly used in hospitals and the pharmaceutical industry. 

important parts of a vertical autoclave steam sterilizer with labelled image
Image 1: Parts of a vertical autoclave steam sterilizer

Over the past few months, because of the Covid-19 pandemic, there has been a great rise in the usage of the Autoclave as it is a simple and effective equipment to use. 

Uses of Autoclave 

An autoclave is majorly used for sterilization purposes. Sterilization refers to killing tiny microbes that might be present in any container like bacteria, fungi, spores, viruses, germs, etc. In biotechnology, the Autoclave is widely used to sterilize equipment like glassware and media. 

It was invented by Charles Chamber in 1879. And to date, the Autoclave is easily and commercially available with better safety measures and monitoring systems. The autoclave device is a top choice in the pharmaceutical industry, educational institutes, data, and research centers. 

A Brief Look at The Autoclave Method

The method used in Autoclave to remove the germs and make equipment microbes free uses pressure and moist heat. The method of working and the design of the Autoclave refers to the pressure cooker. Moreover, the Autoclave is also known as a pressure sterilizer. 

Main Components Behind the Autoclave 


Steam is one of the crucial elements that is used in steam. To kill the microbe or tiny cell in the container with heat and steam, the temperature must be raised to a degree at which the walls of the proteins in the cells or elements break down.

Steam is an essential and effective medium to break down the cell by transferring heat. Transferring heat, it’s an efficient way to terminate the microbes and germs. 


By sterile goods, most people get the basic idea that they are safe to use and consume because they are free of microorganisms and can be easily used in food production units, research centers, medical, etc.

real lifetime image of the autoclave machine image
A Real lifetime image of the autoclave machine image
Image Soure:

Principle and Working of Autoclave

The Autoclave works under steam and pressure, just like a pressure cooker. The high pressure and high temperature ensure the elimination of microbes like fungi, heat resistant spores, viruses, & bacteria, etc.

The high-temperature breakdowns and deimmunizes the microbial proteins and enzymes. 

Steps involved in working of the autoclave cycle


In this phase, the electric heat produced in the Autoclave boils the water & it generates the steam. By steaming, the trapped air is replaced by steam.

Rising temperature phase 

The temperature rises to the level that is set.

Duration of sterilization 

This is the duration of time in which microbes are killed.

Releasing of pressure 

The pressure produced in the container is released by opening the container. 

Construction & Parts of Autoclave 

Here are the following components used in the making of Autoclave:

Lid/ door

The lid or door is made up of stainless steel and placed at the vessel’s mouth. It allows the vessel to trap and release the heat and pressure inside the vessel and helps in creating a helpful environment to perform sterilization. 

Safety valve

The safety valve is present at the top of the surface of the door or lid, just like we got at the top of the pressure cooker. The safety valve helps the system avoid catastrophic accidents when the pressure inside the system reaches an uncontrollable level.

Vessel or pressure chamber

This is the inner chamber made up of stainless steel, and this is where we keep the equipment that we want to sterilize. Meanwhile, the size of the autoclave chamber varies upon the size of the material.

Electrical heater  

The heater is placed down below the chamber. The working principle of the electric heater is like the mechanism of a geezer. The user needs to maintain the water level according to the markings and take precautions. 

More water might cause the water to enter the material level that is being processed, and less water may cause the burning.

Pressure gauge

This is present at the upper side of the lid; this equipment indicates the pressure applied in the Autoclave. This is an important component of the Autoclave as it displays the pressure and the rise of pressure. This component also alerts for any upcoming mishaps. 

Whistle or pressure releasing unit

The pressure releasing unit is also known as a whistle and is placed at the top of the surface. Likewise, the whistle allows us to release the pressure when needed in the pressure cooker. 

vertical construction of autoclave with labelled image with colors
Image 3: Vertical construction of autoclave with labelled image

Types of Autoclaves 

There are 02 types of autoclave systems commercially available:

Gravity displacement

In this type of Autoclave, the steam is produced when the water is boiled, then the steam produced replaces the air by gravity. 

  • Horizontal (comes in horizontal shape)
  • Vertical (comes in vertical shape)

Pressure displacement 

In this Autoclave, the air system is done by mechanical assistance, ensuring steam penetration properly. This type of Autoclave consists of a vacuum pump and steam generator. 

  • Negative pressure displacement 
  • Positive pressure displacement

Operating the Autoclave 

Generally, the Autoclave runs at 121° temperature for 30 minutes with 12 PSI pressure. Here are the numbers of steps to follow when running an autoclave.

  • Before starting the Autoclave, you must check if any previous equipment is left from the cycle. 
  • The chamber is filled with water according to the markings.
  • Then, the materials that need to be sterilized are placed inside the chamber. 
  • After placing, the lid is closed, screws are tightened, ensuring an air-tight condition and ensuring that the electric heater is on. 
  • After that, safety valves are adjusted to produce the needful pressure in the chamber.
  • After the heater is on, the water starts to boil, and the mixture of air and water are, known as moist, is allowed to escape from the discharge tube.
  • After this, the drainage pipe is closed, allowing the steam to reach the desired levels. 
  • After reaching the desired pressure, the pressure-releasing unit blows a whistle. This releases the extra pressure from the chamber. 
  • Then the Autoclave is run for a longer period, i.e., 15 minutes usually. 
  • After that, the electric heater goes off, and the Autoclave is set to get cool.
  • Then, the discharge unit is allowed to let the outside air into the chamber of the Autoclave.
  • At the last stage, the lid is opened, and sterilized equipment or material is taken out.   

Uses of Autoclave 

Here are the common uses of Autoclave:

  • They are used to purify and decontaminate biological waste, instruments, and labware and sterilize media materials. 
  • They are also used to sterilize plastic tubes, autoclave containers, culture media.
  • Moreover, to regulate the medical waste containing viruses, bacteria, infections, and other biological materials.
  • These are widely used in medical labs to sterilize glassware, medical waste, and surgical equipment.  

Wrapping up 

There are two types of autoclaves based on their usage. First, the one that can be placed in your workplace is a tabletop autoclave or bench autoclave. On the other side, the Autoclave that is not portable and cannot be placed on the floor is known as the floor autoclave. There are some important precautions mentioned above that one must take before using the Autoclave. 

Frequently Asked Questions

Q1. What can’t be used in an autoclave?

Here are some the things that can’t be sterilized in an autoclave:
1. Reactive or corrosive substances
2. Flammable material
3. Acids
4. Radioactive material
5. Any chlorine-based substance or products 

Q2. How long should an autoclave last?

Normally. An autoclave lasts for more than 30 years.

Q3. What is the main working principle of the autoclave?

The main working principle of the autoclave is the moist heat sterilization. Pressure Is generated along the rising of the temperature to kill the microbes.


  1. Sasaki, J. I., & Imazato, S. (2020). Autoclave sterilization of dental handpieces: A literature review. journal of prosthodontic research, 64(3), 239-242.
  2. What is Autoclave Sterilization? Meaning, Video, Parameters, Components & Autoclaving – Biology Reader
  3. The Autoclave Sterilization Process and How It Works | Sterilis Solutions
  4. Steam Sterilization | Disinfection & Sterilization Guidelines | Guidelines Library | Infection Control | CDC

Leave a Reply

Your email address will not be published. Required fields are marked *