Any such laboratory, especially the medical field related one has the use of numerous glassware’s and other apparatus. These equipment’s (test tubes, petri dish, flasks, measuring cylinders, pipettes, tongs, dissection tools, etc.) may easily comes in contact with microbes that can be highly infected viruses or bacteria on the regular basis.
Rinsing it with normal detergents, soaps and water cannot guarantee the removal of these microbes, they can still persist on the surface of the glass wares, therefore, the autoclaving is considered to be the best way to get rid of such infectious microorganisms. To ensure that the contaminants are properly killed, the scientific equipment’s are subjected to the heat and pressure up to certain time and temperature.
In the previous articles we briefly described the autoclave machine and its working, this article will continue to elaborate on the autoclave principles, types and its uses.
Working Principles
The autoclave is a machine that is just the advanced version of the pressure cooker, and is also known by the name steam sterilizer. The machine that provides artificial heat and pressure with a purpose of making the laboratory equipment’s microbes free. The autoclave machine uses high-pressure of 121 °Celsius or 250 ° Fahrenheit for about 15 minutes and the process is commonly known as ‘autoclaving to sterilize the stuff kept inside it’.
Components or Parts of an Autoclave
An autoclave machine is made up of few small though important parts, without which it cannot work properly. Lets discuss and understand the significance of such components.
1. Lid or Door – As the name says, it is the cover of the autoclave that seal the machine and thereby crucial in creating and maintain the temperature and pressure for the sterilization. Generally, the lid is made up of the asbestos washer, and screw clamp that makes is air tight.
2. Pressure Gauge – The role of the pressure gauge is to indicate the pressure generated in the autoclave machine during the sterilization process. The significance of pressure gauge is to assure the safety and the working of the autoclave while its working.
3. Release Valve – Also known as ‘whistle or pressure releasing valve, which is found at the lid of the autoclave machine. The role of the whistle is same as the whistle of the pressure cooker, as it releases the vapor that is created inside the machine by lifting itself and thereby controls the pressure.
4. Safety Valve – This is also present on the lid of the autoclave, and it maintains the pressure inside the autoclave either when autoclave machine is not able to create the required amount of pressure or in case if extra pressure is created in the machine. Therefore, it helps in sudden bursting of the machine. This valve consist of a thin layer of rubber and that gets burst to release the pressure.
5. Steam Generator – Also known as electrical heater or boiler, is present underneath the chamber and is connected to the electrical supplies as this is an electrical heating system. The role is create the heat and steam in the inner and outer chamber of the machine. Noticeable thing is that, the consistency or the level of the water in the inner chamber should be maintained as it prevent the burning of the heating system. Even, more amount of the water than the required one may leads to get interfere with the components and tray present within the chamber .
6. Wastewater Cooler – This system is related to the cooling feature of the machine, as the system of an autoclave is designed in such a way that allow it cool down before entering into the draining pipe. Therefore, the significance of the wastewater cooler is to prevent the damage caused due to hot water and steam, that will be sent out of the after the process is completed.
7. Vacuum generator ( if present) – In certain types of the autoclaves the separate vacuum generator is provided, and this function in pulling out the air form the inner chamber and creates a vacuum over there ( inside the chamber). it is been observed that presence os some air pockets within the inner chamber, supports the growth of the other microorganisms.
8. Pressure Chamber – The most crucial part of the steam autoclave is the pressure chamber that is made up of the inner chamber and the outer jacket. The inner chamber is made up the stainless steel or gunmetal, while the outer jacket is made up of iron case. In the inner chamber the equipment’s that are needed to be sterilized are kept, while the outer jacket maintains the temperature of the inner and outer environment. The inner chamber may vary in size and ranges from 100 L to 3000 L.
Types of Autoclaves
Following are the different types of autoclaves that are used according to the requirement of the place.
Laboratory Benchtop/ Pressure Cooker type Autoclaves (N-type)
These types are similar to the large pressure cookers used domestically in numerous parts of the world, and in small clinics and laboratory. These autoclaves are sealed with a rubber gasket and has a metal chamber with a metal lid. It consist of other parts such as safety valve, pressure gauge and steam discharge tap. Even few of them has the electric immersion heater at the bottom of the container.
Gravity Displacement Autoclave
The most common type of autoclave used in laboratories, in this type the steam is been generated inside the chamber through an heating equipment and then it moves around the chamber for sterilization. This is cheaper one one among all and so is in use also. Therefore, can be used in in school, colleges also to perform the small experiments,
B-type Autoclave (Positive Pressure Displacement)
In this type, the steam generator is used separately to generate the steam which is then transferred to the autoclave, however it takes less time than the other autoclave as the steam is generated within a few seconds. This type of autoclave is the advanced version of the gravity displacement type.
S-type Autoclave (Negative Pressure Displacement)
This type of an autoclave is the most advanced of all and consist of the steam and vacuum generator as well. As the role of vacuum generator is to pull the unwanted air from the inner chamber of an autoclave whereas steam generator creates the steam at high speed, which is then passed into an autoclave.
This is highly preferable and recommended one to get the accurate and high level of sterility level, but it is quite expensive too.
Other Types of Autoclaves
The other types of autoclaves are also seen in the market and at different places that are of different shapes and size. For instance, there comes the horizontal as well as the vertical autoclaves, while some are compact like microwave and soe looks like a cabin-size vault.
Uses of Autoclaves
So far, we came to know the working and types of the autoclave machine, so lets dig more to get the use of autoclave machine:
- First and foremost use of an autoclave machine for the sterilizing the equipment’s, that are used in laboratories and other clinical purposes.
- They are used to decontaminate the certain biological waste to sterilize the labware’s, instruments, and sterilize media.
- Before the disposal of the medical waste, it is suggested to sterilize such things as it may contain the infectious microorganisms, for this autoclave is the best way.
- In case of medical labs, the autoclaves are used to sterilize the glassware’s, surgical instruments, medical equipment’s and other medical wastes.
- Moreover, autoclaves are even used for the sterilization of the autoclavable containers, culture media, pipettes, plastic tubes, test tubes, etc.
