Autoclaves: Principles, Uses, Types and Procedures

Autoclaves: Principles, Uses, Types and Procedures
Authored By Tom Toi

Have you ever heard of an autoclave? An autoclave is a sterilisation device that is widely used in a range of settings, from hospitals and laboratories to even tattoo studios and beauty salons. 

In this article, we’ll be talking all about autoclaves: the principles, the uses, the types, and the procedures for using it.

What Is An Autoclave, And What Principle Does It Follow?

An autoclave is a device that works on the principle of moist heat sterilisation, wherein saturated steam is generated under pressure in order to kill microorganisms such as bacteria, viruses, and even heat-resistant endospores from various types of instruments. This is done by heating the instruments within the device to temperatures surpassing the boiling point of water.

This process is also embodied by gas laws, which basically states that the higher the pressure is within the device, the higher the temperature increases. In other words, pressure and temperature are directly proportional to each other.

It is also important to note that it is the temperature that kills the microorganisms, not pressure. Rather, higher pressures are capable of increasing the boiling point of water, which thus increases the temperature of sterilisation. High pressure also helps heat to rapidly spread within the material.

Steam sterilisation is effective because the moisture of the steam helps coagulate the proteins that microbes thrive on. Coagulating the proteins disables the microbes and eventually kills them. 

Autoclaves typically yield a temperature of about 121 degrees Celsius, taking about 15-20 minutes to complete the sterilisation process. However, autoclave cycles may be adjusted accordingly by the working technician. 

We see here that autoclaves are grounded on three factors, namely: pressure, temperature, and time. These three factors all work together to create saturated steam, within a particular time frame, that can kill all signs of microbial life, whether they are in vegetative or spore form.

Autoclaves Principles Uses Types Procedures

What Are The Uses Of Autoclaves?

Autoclaves are capable of sterilising solids, liquids, hollows, and other instruments that come in varying shapes and sizes. Some examples of this may include surgical equipment, pharmaceutical objects, laboratory instruments, and many others.

Other examples of what autoclaves can sterilise include culture media, autoclavable plastic materials, solutions and water, selective glassware, pipette tips, plastic tubes, and biohazardous waste. 

Since autoclaves are effective at killing all signs of microbial life, they are used in all types of settings. In fact, even tattoo studios and beauty salons have autoclaves to sterilise their equipment.

Autoclaves are trusted sterilisation devices because they are capable of killing microorganisms that are resistant to boiling water and other powerful detergents. 

What Are The Types Of Autoclaves?

Though there are different types of autoclaves, all of them operate the same way. The type of autoclave depends on what setting they will be used in. Here are some of them:

1). Pressure Cooker Type/Laboratory Bench Autoclaves (N-type): This autoclave is commonly used around the world. It contains an air and steam discharge tap, a safety valve, and a pressure gauge. It also contains an electric immersion heater located at the bottom of the chamber.

2). Gravity Displacement Autoclave: These are commonly used in laboratories. This autoclave generates steam inside the chamber through a heating unit, which can move within the chamber for optimal sterilisation. It is also relatively cheaper compared to other autoclaves.

3). Positive Pressure Displacement Autoclave (B-type): This type of autoclave generates steam in a separate steam generator unit, which then transfers the steam into the autoclave. It is known to be faster since steam can be generated in just seconds. 

4). Negative Pressure Displacement Autoclave (S-type): Negative pressure displacement autoclaves have both a steam generator and a vacuum generator. The vacuum generator sucks out all the air within the autoclave, while the steam generator, like the positive pressure displacement autoclave, generates heat and passes it into the autoclave. This autoclave is the most recommended, but also the most expensive. 

Autoclaves Principles Uses Types Procedures

What Is The Procedure For Operating An Autoclave?

So, how do you actually use an autoclave? Here is a helpful step-by-step guide:

1). Check if there are previous instruments contained within the chamber.

2). Put water in the chamber and make sure it is the right amount.

3). Place the instruments inside the chamber.

4). Close the lid and tighten the screws then switch on the electric heater.

5). Adjust the safety valves to maintain the required pressure level within the chamber.

6). Once the water within the chamber begins to boil, the air-water mixture can escape through the discharge tube in order to displace all the air inside. Complete displacement is evident when no more water bubbles come out from the pipe.

7). Close the drainage pipe and let the steam reach the desired level.

8). Once the pressure level has been reached, blow the whistle to remove all the excess pressure within the chamber.

9). Let the autoclave run for the set time period after the whistle.

10). Switch off the electric heater and let the autoclave cool until the pressure within the chamber has lowered down to the atmospheric pressure.

11). Open the discharge pipe to allow air from outside the autoclave to enter. 

12). Open the lid and remove the instruments from the chamber.


Autoclaves make use of steam sterilisation that is grounded in pressure, temperature and time, all of which work together to kill all signs of microbial life, especially those that are resistant to boiling water and powerful detergents.

Steam sterilisation is used to disinfect instruments, solid, hollow, or liquid, from all types of backgrounds and settings. 

There are various types of autoclaves, but they all function the same way. Take all the necessary precautions when carrying out autoclaving procedures, and make sure that you have an experienced technician to help guide you through this process.

MES Medical Equipment Services has been Australia’s leading provider of autoclaves and other medical equipment and equipment services since 1952. 

We were originally established to provide electro-medical products to healthcare professionals across the country. 

Our products range from sterilisation, dental systems, dental imaging, electrosurgical equipment, medical consumables,  dental lasers, and equipment service maintenance.

We sell only top of the line equipment and machines produced by the leading manufacturers in the world. Our integrity and standards are your guarantees!

If you are searching for the best autoclave supplier in Australia, then look no further than Medical Equipment Services Australia

For all your medical and dental supply requirements, please call us today on 1300 342 013 or contact us through our website.

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