BS EN 13060 defines three classes of small steam sterilisers. HTM 01-05 notes that Type B (vacuum) sterilisers are recommended for wrapped and hollow instruments, including dental handpieces. Type N (non-vacuum) sterilisers are suitable for simple, solid, unwrapped instruments only. Choosing the wrong class means your instruments may not be sterilised — even if the autoclave report says the cycle passed.
The European standard EN 13060, adopted by BSI as BS EN 13060, defines three classes of small steam sterilisers based on their ability to process different load types. Class B (Big autoclave) handles all loads: solid, wrapped, hollow, and porous instruments. Class N (Naked) handles only solid unwrapped instruments. Class S (Specified) handles specific loads defined by the manufacturer — its capabilities vary from model to model.
The fundamental difference is the vacuum system. Class B autoclaves use a fractionated pre-vacuum that evacuates air from the chamber and from internal channels of hollow instruments before injecting steam. Without this pre-vacuum, steam cannot penetrate the lumens of hollow instruments (turbines, contra-angle handpieces, cannulae) — trapped air creates unsterilised pockets.
HTM 01-05 recommends Type B vacuum sterilisers for wrapped and hollow instruments, including dental handpieces. A Type B steriliser with a fractionated pre-vacuum cycle is the only class that reliably sterilises the internal channels of hollow instruments and allows storage of wrapped loads. For dental practices processing turbines, contra-angles, and ultrasonic scaler tips, Class B is the practical necessity.
HTM 01-05 also notes that unwrapped instruments must be used on the day of sterilisation — storage of unwrapped instruments is not allowed. This effectively eliminates Class N for any practice that needs to store sterilised instruments, which is virtually all dental practices.
Class N autoclaves sterilise only solid, unwrapped, non-hollow instruments. HTM 01-05 notes that Type N is suitable for simple, solid, unwrapped instruments only. Instruments must be used immediately after the cycle — they cannot be stored in pouches. For dental practices, this is insufficient under HTM 01-05. For tattoo or piercing studios using only solid instruments without pouches, Class N may be technically acceptable as a minimum, though Class B remains the professional standard.
Class S autoclaves have capabilities defined by the manufacturer. Some models handle wrapped loads but not hollow instruments. Others handle certain types of hollow loads. It is essential to check the exact manufacturer specifications and ensure they cover the instrument types used in your practice. When in doubt, Class B is the safe choice.
HTM 01-05 requires a daily steam penetration test (Helix or Bowie-Dick) before the first load for Type S and Type B vacuum sterilisers, plus an automatic control test for all benchtop sterilisers. Periodic testing — including vacuum leak tests, safety device checks, and steam penetration verification — should be carried out according to the manufacturer's instructions. A failed test means the load is not sterilised, regardless of what the cycle report shows.
For details on testing requirements, see the biological controls guide. SecuSteri tracks cycles from all autoclave brands (W&H, Melag, Euronda, Castellini, Tuttnauer, and others) — regardless of class.
Dental practice: Class B recommended by HTM 01-05 (hollow instruments, wrapped storage). Podiatrist: Class B recommended for invasive procedures with hollow instruments. Tattoo artist and piercer: Class B recommended as best practice, Class N minimum if only solid unwrapped instruments. Permanent makeup: Class B recommended (handpieces with hollow components).
To understand what your traceability record should contain after each cycle, see the traceability sheet guide.
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