What distinguishes a 'B'-type autoclave from an 'N'-type autoclave?

A 'B'-type autoclave is characterized by its use of a vacuum to remove air before the steam enters the chamber, which enhances the efficiency of the sterilization process. This vacuum ensures that steam can penetrate and contact the instruments being sterilized more effectively, particularly if they are wrapped or packaged.

In contrast, an 'N'-type autoclave typically does not utilize a vacuum and relies on gravity to displace air. This distinction is important in practice because it affects the types of materials and instruments that can be successfully sterilized. B-type autoclaves are generally more versatile, allowing for the sterilization of porous loads and wrapped items, while N-type units are more suitable for non-porous items that do not require the same degree of penetration.

Thus, the presence of a vacuum in a 'B'-type autoclave is what significantly differentiates it from an 'N'-type, making it capable of achieving sterilization under conditions that require thorough steam penetration.