Steam sterilisation criteria according to EN 285:2015
J.P.C.M. van Doornmalen Gomez Hoyos*, R.A.C. van Wezel, T. Onsea, H. Oussoren, K. Henrotin, K. Kopinga
Background: Steam sterilisation conditions are not unambiguously quantified in the literature and standards. In practical situations, it would be helpful if a set of criteria to assess the actual surface steam sterilisation conditions would be available.
Aim: To define numerically quantified steam sterilisation conditions based on the literature and standards. This means that the combinations of temperature, water vapour fraction, and time are specified in terms of numerical values, including their possible inaccuracies.
Methodology: A review of the literature and standards is performed. Results from this review, combined with basic physical calculations, are used to determine numerically quantified steam sterilisation conditions.
Results: Steam sterilisation conditions can be specified in terms of quantified physical parameters. For example, to comply with European standard EN 285:2015 these parameters are a holding time of 3 minutes or more, at measured temperatures between 134.5 and 136.5 °C, and a minimum water vapour fraction depending on load temperature and pressure.
Conclusion: The standard EN 285:2015 allows parameter regions where sterilisation conditions are not met, even in the absence of non-condensable gases. If the inaccuracies in the temperature measurements are properly taken into account and the water vapour fraction is measured, sterilization conditions can be guaranteed.
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