The principle of the pressure steam sterilizer is: in a closed steamer, the steam in it cannot escape, and the pressure continues to rise, so that the boiling point of the water is continuously increased, and the temperature in the pot also increases accordingly. Under the pressure of 0.1MPa, the temperature in the pot reaches 121°C. At this steam temperature, all kinds of bacteria can be quickly killed and its highly heat-resistant principle.

For items that do not deteriorate after autoclaving by pressure steam sterilizer, such as sterile water, cultivation medium, and inoculation equipment, the sterilization time can be extended or the pressure can be increased. The culture medium must strictly abide by the holding time. It is necessary to maintain the pressure and prevent the components in the medium from deteriorating or reducing their effectiveness. The time cannot be extended arbitrarily. In short: the lower the sterilization temperature, the longer the sterilization time required; the higher the sterilization temperature, the shorter the sterilization time required. The time of pressure steam sterilization shall be calculated from the time when the sterilizer cabinet reaches the required temperature for sterilization until the sterilization is completed. Total time includes:

1. Heat penetration time

That is, the time required from reaching the sterilization temperature in the disinfection cabinet to reaching the sterilization temperature in the center of the sterilized item. The length of time depends on the nature of the sterilized items, the size of the package, the placement location, the degree of air evacuation in the pressure cooker and the type of sterilizer.

2. Disinfection maintenance time

That is, the time required to kill microorganisms is generally expressed by the time required to kill thermophilic bacteria spores. It takes 30 minutes at 115°C, 12 minutes at 121°C, and 2 minutes at 132°C.

3. Safety time

Generally, it is half of the maintenance time, and its length depends on the disinfection items. For the sterilization of heat-conducting metal equipment, no safety time is required.