Autoclave class B, N, S in Malta: which one does your practice need?

The three EN 13060 classes

The European standard 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.

Class B: the standard for dental practices

The Standards for Dental Clinics (March 2024) specifies a Class B steriliser (small / portable / bench-top) or evidence-based equivalent for Maltese dental clinics. In practice, Class B is the only choice for sterilising wrapped and hollow instruments — turbines, contra-angle handpieces, ultrasonic scaler tips — that are routine in dental work. Thermal validation follows EN ISO 17665-1.

Where unwrapped instruments are processed, they must be used promptly and not stored — wrapped processing in Class B pouches is the universal route for any clinic that needs to store sterilised instruments, which is virtually all dental practices.

Class N: limited to solid unwrapped instruments

Class N autoclaves sterilise only solid, unwrapped, non-hollow instruments. Instruments must be used immediately after the cycle — they cannot be stored in pouches. For dental practices, this is insufficient under the Standards for Dental Clinics. 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 alongside single-use sterile needles.

Class S: check the manufacturer's specifications

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.

How to verify your autoclave is working correctly

The Standards for Dental Clinics expects daily Bowie-Dick or Helix tests before the first load. The Bowie-Dick test verifies steam penetration for Class B autoclaves. The Helix test is specifically designed to validate sterilisation of hollow instruments. Weekly tests — vacuum leak, door seal, and automatic control checks — are also expected. 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.

Summary by profession

Dental practice: Class B required in practice under the Standards for Dental Clinics (hollow instruments, wrapped storage). Podiatry: Class B recommended for invasive procedures with hollow instruments and for surgical podiatry under the CPCM scope of practice. Tattoo artist and piercer: Class B is the practical standard for any reusable instruments under the Standards for Tattoo and Body Piercing (January 2025), alongside single-use sterile needles. Semi-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.