The newly published ISO 14644 part 21 provides clarification on the application of sound airborne particle sampling techniques in support of ISO 14644-1:2015 for classification of cleanrooms and clean zones, and ISO 14644-2:2015 for airborne particle monitoring, to provide evidence of cleanroom performance related to air cleanliness by particle concentration.
It addresses a potential misinterpretation of the use of ISO 14644-1:2015, C.4.1.2 in informative Annex C, which suggests the use of limited tubing length for sampling macroparticles. This document also provides extra clarity on the use of the M Descriptor in ISO 14644-1:2015, Annex C, specifically in relation to consideration of >5,0 µm alongside ISO Class 5 (EU-PIC/S GMP Grade A and B at rest). It provides information on the uncertainty associated with sampling particles ≥5,0 µm and macro-particles, and steps to reduce that uncertainty.
It reviews the following aspects:
• for classification, the quality of the sample is the most important factor;
• for monitoring, the quality of the data is the most important factor;
• Sample tubing applications and limitations on the accuracy implications of using tubing at a significant or critical location;
• to reduce sampling loss in tubing, this tubing is as short and straight as possible;
• a sampling system is evaluated using a flow diagram to assess the impact of any tubing or valves used.