What is Autoclave Principle? Complete Guide with Diagram

The process of sterilization in laboratories, healthcare facilities, microbiology laboratories, and pharmaceutical companies is based on the principle of the autoclave. The understanding of the autoclave principle guarantees the sterilization of all laboratory items and waste.

How the autoclave principle operates is based on moist heat sterilization through the use of saturated steam under pressure. Through pressure increase in a closed chamber, the boiling point of water goes above 100°C to enable steam to attain a high temperature to destroy bacteria, fungi, viruses, and heat resistant spores.

To give an outright answer: The autoclave operates at 121°C and 15 PSI for 15-20 minutes.

Understanding the Autoclave Principle and Procedure


What is Autoclave Principle?


Sterilization by moist heat by the process of using steam at high pressure is what constitutes the basics of autoclaving. It is a more powerful form of sterilization since steam at high pressure can penetrate the materials deeply.

Water normally boils at 100°C when the atmospheric pressure is one atmosphere. In an autoclave, on the other hand, the pressure becomes 15 PSI making the boiling point of water 121°C.

Such a combination of:

  • High Temperature

  • Pressure

  • and Saturated Steam


makes autoclave sterilization very efficient.

Autoclave Principle Temperature


The most frequently used temperatures in the autoclave principle are the following:

  • 121°C at 15 PSI for 15-20 minutes

  • 134°C at 30 PSI for 3-5 minutes


These temperatures guarantee complete sterilization of any microorganism.

Autoclave Procedure Step by Step


The usual Autoclave procedure involves the following steps:

1. Loading


The items to be sterilized such as instruments, glass wares, media for culture, and wastes are put into the chamber.

2. Air Extraction


The chamber air is extracted as presence of air makes sterilization less effective.

3. Heatin Phase


Steam gets into the chamber resulting in an increase in temperature and pressure.

4. Sterilization Phase


The temperature and pressure of the chamber stay at the required levels for a specific period of time.

5. Exhaust Phase


The pressure gets released gradually.

6. Cooling Phase


The items get cooled.

7. Unloading


The sterile items are removed.

This is the whole concept of the autoclave procedure.

Autoclave Diagram and Main Components


The knowledge of autoclave diagram enables one to use the device correctly.

  • Components include:

  • Pressure chamber

  • Steam generator

  • Heating element

  • Pressure gauge

  • Safety valve

  • Control panel

  • Drain system


All these components work collectively for sterilization purposes.

Autoclave Uses


Autoclaves have numerous applications within various sectors.

Typical examples are:

  • Laboratory sterilization

  • Sterilization of instruments in hospitals

  • Microbiology testing

  • Manufacturing pharmaceuticals

  • Decontamination of waste


The diverse applications of autoclaves ensure that they are very important.

Case Study: Laboratory Sterilization Success


A diagnostic laboratory in Delhi had some problems with its cultures due to contamination.

With the help of installing an excellent autoclave from Bionics Scientific, the laboratory was able to achieve:

  • Contamination reduction of 99.9%

  • Reliable samples

  • Higher compliance with safety standards

  • Efficient workflow


That’s how important it is to understand the principle of autoclaving.

Types of Autoclaves


Four types of autoclave exist:

  • Vertical autoclave

  • Horizontal autoclave

  • Portable autoclave

  • Vacuum autoclave


Each type is used for particular purposes.

Importance of Autoclave Sterilization


Autoclaving sterilization is more preferable due to the following reasons:

  • Effective sterilization

  • Quick completion of the cycle

  • Penetration of deep steam

  • Cost-effective operation

  • High safety measures


Dry heat sterilization is less efficient compared to autoclaving.

Autoclave Principle PDF & PPT


Most people look for:

  • Principle of autoclave pdf

  • Principle of autoclave ppt

  • This information can be helpful to:

  • Students

  • Laboratory technicians

  • Medical practitioners

  • Training sessions


They make the understanding easier.

Common Mistakes to Avoid


Sterilization should be avoided when:

  • The chamber is overloaded

  • Wrong cycle is used

  • Poor maintenance

  • Skip testing of indicators


It may lead to ineffective sterilization

FAQs: Autoclave Principle


What is the basic principle of autoclaving?


The basic principle of autoclaving is the process of moist heat sterilization through the application of pressurized steam.

What are the four kinds of autoclaves?


They are vertical, horizontal, portable, and vacuum autoclaves.

Why is 121 utilized in autoclaving?


It is very efficient in killing bacteria, fungi, viruses, and spores.

What is the theory of sterilization?


All microbes get eliminated through sterilization via heat, steam, chemical process, or radiations.

What are the seven phases of sterilization?


Loading, evacuation, heating, sterilizing, venting, cooling, and unloading.

What are the five applications of autoclave?


Laboratory sterilization, Hospital equipment sterilization, microbiological experiments, pharmaceutical products, and waste treatment.

What are the three components of the autoclave?


Pressure, heat, steam.

What are the pressure and temperature for an autoclave?


The standard pressure and temperature for an autoclave are 121° C and 15 PSI for 15 to 20 minutes.

What are the five types of sterilization indicators?


Chemical sterilization indicators.

What are the various methods of sterilization ?


Moist heat sterilization and dry heat sterilization.

What is a type B autoclave?


It is an autoclave that utilizes vacuum technology for its high sterilization performance.

Final Thoughts 


The autoclave principle is an important concept in modern-day sterilization processes because it uses steam, pressure, and heat to completely eliminate microorganisms.

It is vital for all health care professionals, researchers, and other professionals working in the field of pharma or diagnostics to have knowledge of the autoclave principle, autoclave sterilization, and autoclave process.

Connect With Us: Bionics Scientific


A Laboratory Equipment Manufacturing Company Certified with ISO 9001:2008

  • Address: 314, 3rd Floor, Vardhman Capital Mall LSC-10, Sindhora Kalan, Delhi – 110052, India

  • Mobile: +91 9111161955 | 9376651333

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