Autoclaves commonly sterilise by exposing its items to elevated temperatures of 121 to 134ºC under pressure of 15 to 30 psi, for a holding time of anywhere between three to 30 minutes. The combination of the time, temperature and steam, deliver a powerful kill rate which even the hardest of bacteria find hard to survive. This effective and yet clean method of lethality is unmatched by any of the other methods of sterilization.
However, if there is residual air in the chamber and load, it will interfere with steam-instrument contact and may compromise sterilisation. This residual air can prevent penetration of steam to the depths of the instruments leaving your sterilisation incomplete. When you load the autoclave with instruments and close the lid, there is already a lot of stale air trapped inside. For sterilisation to take place, this air needs to be effectively purged and replaced with saturated steam. To resolve this problem of purging entrapped air, normal autoclaves have a manually operated valve open till about 100ºC. Once it is closed, the pressure and temperature begins to rise. It is presumed that by this time, the entire entrapped inner air has been purged. However, tests have shown that this is not an effective method for vials, wrapped items, implants, garments and certain types of hollow ware. You can never be assured of efficient penetration of steam right inside, if you are using a regular autoclave. Even a small volume of entrapped air can compromise your sterility assurance level simply because ordinary entrapped air is a very bad conductor of heat and moisture. These pockets of air cannot conduct heat to the load with the same vigour as steam and therefore cold spots remain within the load.
The regular (type N) is suitable for sterilizing only unwrapped and solid instruments. The major concern with the N-cycle sterilizers is the non-removal of trapped air, especially air pockets in difficult-to-access areas of the instruments during displacement. Errors in packaging or overloading the sterilizer chamber can result in cool air pockets where items are not sterilized.
The type B sterilization cycle is used to process loads that can retain air. It can sterilize solid, hollow, and porous instruments, be they wrapped or unwrapped. B-cycle involves the use of active (forced) air removal, usually by using an inbuilt vacuum pump. These pre-vacuum or Class-B sterilizers create a vacuum, thus removing air from the load prior to the chamber being pressurized with steam. This can be done from one to three times, depending on the cycle selected. This technique allows faster and more effective steam penetration throughout the entire instrument load than the regular autoclaves. You are assured of 100% safety with our sterilization technique!