N-type bare instruments, B-type is pre-vacuum, S-type is lower exhaust.
N-type pressure steam sterilizer: there is no vacuum process in the sterilizer before steam sterilization, i.e., the sterilizer cannot be pre-vacuumed, and it is only suitable for sterilizing general solid metal instruments.
S-type pressure steam sterilizer: before steam sterilization, the space inside the pot for a vacuum process, and then enter the disinfection process of high-pressure steam sterilization pot, can be used for oral cavity, five senses, ophthalmology, gynecology, and other solid instruments, appliances sterilization.
Pressurization and depressurization
The basic principle of exhaustion is the same for both, both are due to the pressure and temperature inside the sterilization chamber is higher than that outside the chamber, and the colder air is discharged to the outside of the chamber. Vacuum sterilizers use a vacuum pump to lower the pressure outside the sterilization chamber in order to move air from the high-pressure sterilization chamber to the outside of the lower-pressure vacuum pump. Pressure steam sterilizers, on the other hand, create an internal and external pressure differential by increasing the pressure inside the sterilization chamber. The difference is that the vacuum, which creates a negative pressure below atmospheric pressure inside the sterilization chamber, pulls the air out.
Reference for the above: Baidu Encyclopedia-Pressure Sterilizer