NEN-EN 13060 defines three classes of small steam sterilizers. The KNMT guideline on infection prevention and the NVvP practice guideline 2021 identify class B (vacuum process) as the standard for hollow- and porous-load instruments — the majority of dental and podiatry instruments. For tattooing and piercing, class B is likewise the state of the art under NEN-EN 17169:2020. Choosing the wrong class means your instruments may not be sterilized — regardless of what the cycle report says.
NEN-EN 13060, the Dutch adoption of the European standard 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 which instruments each autoclave can sterilize and, therefore, which class is appropriate for each profession. The Wkkgz (Care quality, complaints and disputes act) Articles 2 and 3 and the KNMT guideline on infection prevention require the use of standards-compliant reprocessing equipment -- application of the harmonized NEN-EN standards provides the basis for demonstrating the state of the art.
Class B (Big autoclave, small sterilizer) is the most versatile class. It features a fractionated pre-vacuum system that evacuates air from the chamber and from the internal channels of hollow instruments (dental turbines, contra-angle handpieces, cannulae) before steam injection. Only class B can reliably sterilize wrapped loads, hollow instruments, and textiles.
In the Netherlands, class B is effectively mandatory for dental practices: critical-B instruments -- those with lumens -- require a class B autoclave and prior machine cleaning and disinfection in a washer-disinfector per NEN-EN-ISO 15883, as specified by the KNMT guideline on infection prevention in dental practices. The KNMT guideline recommends class B as the standard for all dental offices. For tattoo studios using hollow instruments, class B is likewise the only safe choice (NEN-EN 17169:2020, Stcrt. 2022, 4132).
Class N (Naked) can only process solid, unwrapped, non-hollow instruments. There is no pre-vacuum -- air displacement occurs 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, as they lose sterility upon contact with ambient air without packaging.
In Dutch practice, class N has very limited application: it does not allow sterilization of wrapped instruments (no use-by date possible), cannot process hollow instruments, and does not provide the traceability required by the KNMT guideline and the NVvP practice guideline on hygiene and infection prevention 2021. Its use is restricted 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 their class S autoclave can process (e.g., "solid wrapped instruments" or "hollow type A instruments"). The available cycles and permitted loads vary from model to model -- there is no single standard for class S.
Before purchasing a class S autoclave, it is essential to verify that the manufacturer's declared cycles cover the specific requirements of your practice. When in doubt, class B is always the safest choice: it covers all load types and avoids the risk of using an unsuitable cycle for a particular instrument type.
Regardless of class, every autoclave must undergo regular controls: a daily Bowie-Dick or helix test before the first load (mandatory for class B and class S with pre-vacuum, per the KNMT guideline on infection prevention), chemical indicators in every load, weekly biological indicators (spore tests with Geobacillus stearothermophilus), a weekly vacuum leak test (class B), and maintenance per the manufacturer's instructions. For details on mandatory controls, see the biological controls guide.
Dental practices: class B effectively mandatory -- rotary instruments (turbines, contra-angle handpieces) are hollow and must be sterilized wrapped. The standard cycle is 134 degrees C for 18 minutes (prion cycle). The KNMT guideline additionally requires machine pre-cleaning in a washer-disinfector for critical-B instruments.
Tattoo, piercing, and permanent makeup: class B recommended per NEN-EN 17169:2020 and the LCHV hygiene guideline. The Warenwetbesluit on tattooing and piercing (BWBR0021605) requires sterilization of reusable instruments -- class B enables wrapping and assignment of a use-by date.
Podiatry: class B recommended for all invasive instruments. Surgical instruments (scalpels, curettes, gouges) must be sterilized wrapped to maintain sterility until use -- a requirement of the NVvP practice guideline on hygiene and infection prevention 2021. For details on load documentation requirements, 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.