UNI EN 13060 classifies small steam autoclaves into three classes: Class B (all load types — solid, porous, hollow, wrapped), Class S (specific loads defined by the manufacturer), Class N (solid unwrapped loads only). For dental practices, Class B is mandatory for sterilizing turbines and handpieces (hollow instruments). Class B is also the standard professional choice for tattoo and podiatry. This guide describes the technical and operational differences and helps you select the correct class for your practice.
The European standard EN 13060, adopted in Italy as UNI EN 13060, classifies small steam sterilizers into three classes based on their steam-penetration capability and the load types they can process. This classification determines what each autoclave can sterilize and, therefore, which class is appropriate for each profession. EU Regulation 2017/745 (MDR) applies directly in Italy and reinforces the obligation to use equipment that complies with harmonized standards. UNI EN ISO 17665-1 defines performance qualification for moist-heat sterilization processes.
Class B (Big autoclave, small sterilizer) is the most versatile. It uses a fractionated pre-vacuum system that removes air from the chamber before steam injection, ensuring that steam penetrates hollow instruments (dental turbines, contra-angles, cannulas), wrapped loads in pouches, and textiles. It is the only class that can reliably sterilize every type of instrument used in a dental or podiatry practice.
In Italy, Class B is mandatory for dental practices that sterilize hollow instruments (turbines, handpieces) under UNI EN 13060. The most structured regional tattoo and piercing laws (Lombardia L.R. 13/2021 + DGR XI/5796) require a Class B autoclave. For studios that process only solid, unwrapped instruments (steel grips with no internal channels), Class S could technically suffice, but Class B offers a wider safety margin and more flexibility.
Class N (Naked) can only process solid, unwrapped instruments, placed directly on the autoclave tray. It does not perform pre-vacuum — air displacement happens by gravity, which is insufficient for hollow instruments or wrapped loads. Instruments sterilized in a Class N autoclave must be used immediately after the cycle, since without packaging they lose sterility as soon as they contact ambient air.
In Italian clinical practice, Class N has very limited use: it does not allow sterilization of wrapped instruments (no use-by date possible), it cannot process hollow instruments, and it does not generate the traceability required by the ISPESL Linee Guida. Its use is limited to immediate sterilization of emergency instruments.
Class S (Specified) is an intermediate category defined by the manufacturer's specifications. The manufacturer declares which load types its Class S autoclave can process (for example, "wrapped solid instruments" or "type A hollow instruments"). The available cycles and permitted loads vary from one model to another — there is no single standard for Class S.
Before purchasing a Class S autoclave, it is essential to verify that the cycles declared by the manufacturer cover the specific needs of your practice. When in doubt, Class B is always the safer choice: it covers every possible load and avoids the risk of running an inadequate cycle for a specific instrument type.
Regardless of class, every autoclave must undergo periodic checks: daily Bowie-Dick or Helix test before the first load (mandatory for Class B and Class S with pre-vacuum), Class 1 chemical indicators (UNI EN ISO 11140-1) on every load, periodic biological controls with Geobacillus stearothermophilus spores at intervals based on risk analysis, periodic vacuum leak test (Class B), annual performance qualification per UNI EN ISO 17665-1, and maintenance per the manufacturer's instructions. For more on these controls, see the biological-controls guide.
Dental practices: Class B mandatory — rotary instruments (turbines, contra-angles) are hollow and must be wrapped. The standard cycle is 134°C for 18 minutes (prion cycle). D.Lgs 81/2008 does not specify the class, but compliance with the ISPESL Linee Guida and UNI EN 13060 for the sterilization of wrapped hollow instruments requires Class B.
Tattoo, piercing, and permanent makeup: Class B required by the most structured regional laws (Lombardia L.R. 13/2021 + DGR XI/5796 mandates an autoclave for reusable instruments). In regions where the law does not specify the class, Class B remains the practical recommendation — it allows wrapping the instruments and assigning a use-by date.
Podiatry: Class B recommended. Instruments used in the podiatry practice (scalpels, gouges, nippers) must be sterilized wrapped to maintain sterility until the moment of use. For more on the traceability sheet, see the traceability-sheet guide.
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For a complete schedule of daily, weekly, monthly, quarterly, and yearly autoclave maintenance tasks, see our Autoclave maintenance guide.