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Autoclave sterilization is a common sterilization method used in biological laboratories. It has a principle of physical/moist sterilization for killing fungi, bacteria, viruses and other microorganisms that occupy laboratory utensils including glassware. This is commonly used in health and research laboratories. It uses a specific temperature and pressure for sterilization. Autoclave was developed to use sterilized utensils that cannot be directly exposed under heat sterilization in an oven.
Principle
The autoclave works on the basic principle of temperature-mediated sterilization or moist sterilization. A gas chamber is the basic structure of the autoclave which fills with the steam of high pressure and temperature. High pressure increases the boiling point of the water and gradually increases the temperature for sterilization. This high pressure can effectively penetrate the heat into the inner part of the object to be sterilized and the steam irreversibly coagulates the proteins in microbes causing loss of functioning of themselves. The fixed temperature and pressure for running the autoclave are 121°C at 15 psi. When the steam is produced at the required temperature and pressure, it comes in contact with the surface of the utensils to get sterilized and kill the microbes.
Components
1. Pressure chamber
It is a two-layered cylindrical structure with an inner chamber and outer jacket to ensure safety. The inner chamber is made up of stainless steel and the outer chamber is made of iron.
2. Lid
It helps to cover the pressure chamber. It helps as a barrier between the atmosphere and a sterile condition inside the chamber.
3. Pressure gauge
The pressure gauge is fixed on the lid of the chamber. This indicates the pressure within the chamber to ensure the autoclave is working properly.
4. Pressure outlet
This outlet is present on the lid of the chamber. It allows releasing excess pressure from the chamber after reaching the limit.
5. Steam maker/generator
It is an electrical unit that is present under the chamber and acts as a boiler to boil water and generate steam.
6. Safety Valve
This is used during an emergency situation, when an autoclave fails and increases the pressure uncontrollably. Then the pressure is released out of the safety valve by bursting itself.
Procedure
- Clear any remnants or previously sterilized utensils left in the chamber before beginning.
- The required amount of water is loaded into the chamber.
- Materials required to get sterilized are loaded in the chamber. Some materials like specific glassware require to get wrapped with wrapping paper for sterilization.
- After loading the lid of the chamber is closed and tightened with screwes in it to ensure airtight condition as well as safety.
- Then the power is on for activating the heater and the pressure valves are adjusted.
- When the chamber containing water boils, through the discharge outlet, the mixture of water containing air will be discharged. After a sufficient amount of outflow, the outlet is closed to ensure sufficient pressure in the chamber.
- The steam is allowed at 15 psi in the chamber. The whistle valve blows once the pressure exceeds the limit and removes excess pressure.
- The power is turned off after the required time and pressure. Allow the system to cool.
- Ensure the pressure is below the atmospheric pressure in the pressure gauge.
- The lid is opened and sterilized utensils/materials are taken out.
Types
1. Vertical autoclaves:
These autoclaves are opened by the topmost lid. It is suitable for small-scale uses including clinics and small test laboratories.
2. Horizontal autoclaves
3. Gravity displacement autoclaves
5. Pre-vaccum autoclaves
This type of autoclave uses a vacuum pump to remove all the air from the autoclave’s chamber, helping in better steam penetration and sterilization of heavy loads of materials.
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Graduated from the University of Kerala with B.Sc. Botany and Biotechnology. M.Sc. Biotechnology from the University of Kerala. Attended certificate course in Artificial Intelligence for Everyone from Deeplearning.AI, Influenza Prevention and Control from World Health Organization. Attended workshops related to Bioinformatics at the University of Kerala. 3 years of experience in website management. Experience in WordPress, Blogger, Google Analytics, and Google Search Console.
