How Sterilisation in an Autoclave Works

An autoclave is a steel vessel in which equipment is placed and is sterilized by steam and high pressure. Autoclaves are used in several industries (such as the medical industry) to clean equipment and keep them bacteria-free. Operating in a similar manner to a pressure cooker, the autoclave is able to clean much more thoroughly than simply using detergents and hot water.

The autoclave itself is a cylindrical chamber in which steam is circulated at high pressure and temperature. Contaminated items are loaded in the front and the door is then shut creating a seal. Several types of seals and gaskets are used in the construction of the autoclave, from door seals to generator gaskets. Made from quality grade silicone, these seals keep moisture etc. from escaping the autoclave, as well as protecting the contents from the outside atmosphere. Some seals will need to be graphited before fitting.

The seals in an autoclave are mainly round either a cord or tube joined to make an endless ring, but in today’s market, the seals are varied and many.

Some of the main manufacturers are listed below:
• BMM
• Getinge
• Tuttnauer
• S.E.C
• Boxer
• MMM

The Sterilisation Process

Autoclaves are used to sterilize equipment by producing high-pressure steam to clean and kill off bacteria. The front door to the autoclave is locked by a manual lock and door seal. Steam is fed into the chamber at a higher atmospheric through a pipe at the bottom. The increased pressure in an autoclave means that the temperature is 20 degrees higher than the normal boiling point of water. A safety valve is fitted to stop the pressure exceeding the permitted maximum.

Once the required temperature has been reached inside the autoclave, a thermostat starts a timer, which generally lasts for 15 – 20 minutes before finishing the sterilization process. The timing depends on the amount of contamination the items inside have previously been subjected to, and how the items have been loaded into the autoclave.