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How does an autoclave work?

Last Updated: 06.12.21


If at first glance an autoclave might seem like a complicated device, the way in which it works is quite straightforward. While most people tend to associate this nifty device with hospitals, it is also essential in tattoo shops, dentist offices, veterinarians, beauty and barber shops, and many other fields.

The autoclave is a pressure chamber that works very similarly to a pressure cooker. It uses high temperatures and pressures to sterilize equipment and supplies. When items are placed inside a quality autoclave sterilizer, they are exposed to high-temperature steam which is usually around 132 degrees Celsius or 270 degrees Fahrenheit, for about twenty minutes.

The time can vary depending on what items you want to sterilize, their physical size or the amount. The hot steam used in this device is capable of killing germs that no simple detergent or boiling water could.

The parts of the autoclave

The large cylindrical chamber is the part of the device that users will interact with the most. Contaminated items are loaded in it, and there may be mountings inside the chamber for trays and shelving. Once you are done loading items, you can seal the door off.

For safety reasons, most options feature a manual lock to keep the door sealed shut so that the contents inside remain secure and no leakage occurs. Apart from the door seal, there are also several other gaskets and seals, including generator gaskets and bed-pan seals.

These will prevent the moisture from getting out of the autoclave and will protect the contents from the outside atmosphere. On every unit, there is a high-quality thermometer that will wait for the thermal sweet point of 268-273 degrees Fahrenheit.

It is also important not to add contents inside the sterilizer that are not clean and free from debris, organic tissues, and blood. People might not consider this detail, but the autoclave is only meant to destroy the germs, not clean the items from dirt and debris.

Before you add an object to be sterilized, doctors, barbers, or tattoo artists will need first to use an effective ultrasonic cleaner to help with the cleaning process.


The autoclave cycle

As mentioned above, the autoclave works very similarly to a pressure cooker in the sense that it forces the moist heat inside of the food to cook it. The difference is that instead of food, you have surgical supplies which need to be sterilized. Placing them inside the cylindrical chamber and running a cycle will force moist heat into all the possible crevices of the equipment.

Thus, for a better understanding of how an autoclave cycle works, we will present you with the steps that the device needs to take when you place items into it all the way until you have to cool the load and open the autoclave door.

The first step that the autoclave will take is to heat up water to the boiling temperature. As the steam will enter the chamber, the air is removed to allow the steam to expand. The air will either be removed by a vacuum process or by a displacement process.

Once the air is removed, the temperature and the pressure are increased even further by closing the chamber exhaust valve. The temperature will continue to rise until it hits 268-273 degrees Fahrenheit. Once this is done, the sterilization time begins, and this might take anywhere between 3 to 20 minutes depending on the size and contents of the load.

When the sterilization process is complete, the pressure inside the unit will be reduced, and the exhaust valve will open and release steam. The final step is to let the load cool down, so that it is safe to handle when you open the door.


Ioana Moldovan

Ioana’s professional experience in the optics field has helped her understand the value of passing her knowledge forward. Her curious personality helps her gather useful information for her readers and her goal is to make technical information fun and accessible to everyone.

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