Autoclave Sterilization Process – A Guide for Technicians

Autoclave sterilization process has to be done systematically and with strict adherence to laid out guidelines if the objects being sterilized, in almost all cases, medical equipment and tools, are to be certified as medically safe to be used on new patients. While it is possible for autoclave technicians to operate the machinery without having the in-depth knowledge about how autoclaves work, this is not ideal. Having a proper understanding of the autoclave sterilization process will help you to become a better operator of the machinery.Autoclave Sterilization Process

Autoclave Sterilization Process in Medical Facilities

Many medical facilities, even when they offer just minor surgical services, own some type of autoclave. For smaller facilities, the autoclave is no larger than a tabletop microwave oven. However, large hospitals where there is constant demand for sterile equipment to be used in multiple operating theaters and emergency rooms require what is known as a large or horizontal autoclave. Such a huge piece of equipment is capable of sterilizing a large collection of surgical instruments.

The Autoclave Steam Sterilization Cycle

Irrespective of the size or application area, the autoclave sterilization process takes the form of four steps. These are namely:-

1. Loading the autoclave

2. Air removal

3. Sterilizing

4. Steam evacuation and drying


1. Loading the Autoclave

Loading the autoclave with the instruments or surgical ware is just as important as the actual sterilization. The objects being sterilized must be loaded in such a way that facilitates the steam to be directly in contact with the surface requiring sterilization.

2. Air Removal

Before the pressure chamber is pumped full of superheated, high pressure steam; the air in it must be vacuumed out. Indicator strips are used to monitor the effectiveness of the air removal stage of the autoclaving process.

3. Sterilizing

The sterilizing stage is carried out with special regard to the sort of objects being sterilized. The amount of pressure in the chamber, the temperature and the length of the cycle will change depending on the type of objects being sterilized. There are different sterilization regimens for:

a. Fabrics

b. Assembled filter units

c. Laboratory plastic and glassware

d. Discard loads

Two important factors are crucial in determining the efficiency of the sterilization. The first one is the thermal death time. This refers to the amount of time required to kill microbes when you expose them to certain high temperatures. The second crucial factor in sterilization is the thermal death point. This is the temperature at which all microbes are killed in the high pressure autoclaving chamber.

4. Steam Evacuation and Drying

After effective sterilization has been done, the high pressure steam in the autoclaving chamber must be gradually lowered. Subsequently, the objects must be allowed to cool down and then dried so that they are ready to be reused on the next patients.


Autoclave sterilization process monitoring and control is very crucial in ensuring that nothing is left to chance when sterilizing instruments and other medical laboratory-ware. A knowledgeable and proficient autoclave technician is better placed to ensure that the equipment under their care and control is used in just the right way to ensure that the objects being treated are completely sterile and ready for the next cycle. While this guide if only elementary, it touches on all the important factors and steps necessary for effective sterilization to take place in an autoclave.