Overview
ISO 14644-8:2022 - "Cleanrooms and associated controlled environments - Part 8: Assessment of air cleanliness by chemical concentration (ACC)" defines a standardized approach to assess air chemical cleanliness (ACC) in cleanrooms and controlled environments. The standard establishes an ISO-ACC grading scale (ISO-ACC Level N) and a descriptor format to specify the maximum allowable airborne concentration of a chemical species, group or category. It applies where airborne chemical substances present a risk to product, process or equipment and is explicit that it does not classify surface chemical contamination.
Key topics and technical requirements
- ISO-ACC descriptor format: Use the format “ISO-ACC Level N (X)” where N is the logarithmic index of concentration (range from 0 to −12) and X identifies the chemical species, group or contaminant category (e.g., acids, bases, organic, oxidant, dopant, condensable, corrosive, biotoxic or named compounds).
- ACC grading levels: Levels map to maximum airborne concentrations expressed in grams per cubic metre. N = log10(c) where c is concentration (g/m3). Example designations in the standard include “ISO-ACC Level −6 (NMP)” and “ISO-ACC Level −4 (TOC)”.
- Testing and monitoring: The document prescribes how to specify testing and monitoring by ACC descriptor, and provides protocols for test selection, sampling periods, time-weighting factors and reporting to demonstrate compliance.
- Demonstration of compliance: Compliance is shown by performing agreed test procedures and documenting results, conditions and analysis methods.
- Informative annexes: Annex A - parameters to consider; Annex B - typical contaminants; Annex C - typical measurement and analysis methods; Annex D - considerations for separative devices.
- Scope limits: Intended only where airborne chemical contamination is a risk; it does not describe contaminant chemistry in detail nor classify surface contamination.
Practical applications and who uses it
ISO 14644-8 is used to specify, test and document chemical cleanliness in environments where trace airborne chemicals can damage products or processes. Typical applications include:
- Pharmaceuticals and medical devices - preventing chemical contamination during sensitive manufacturing and packaging.
- Microelectronics and semiconductors - controlling dopants, organic vapours and condensables that affect yields.
- Optics, displays, photovoltaics and coatings - protecting sensitive surfaces from corrosives or condensables.
- Aerospace, automotive, vacuum technology, instrumentation, food and healthcare - where airborne chemicals can impair performance or safety.
Users: contamination-control engineers, cleanroom designers, quality assurance managers, suppliers, test laboratories and regulatory/compliance teams.
Related standards
- ISO 14644 series (airborne particulate classification and cleanroom design), notably ISO 14644-1 for particle-based classification.
- ISO 14698 series for biocontamination control and related guidance.
Keywords: ISO 14644-8:2022, air chemical cleanliness, ACC, ISO-ACC, cleanrooms, controlled environments, chemical contamination, testing and monitoring, clean-zone compliance.
Open preview (PDF)Cleanrooms and associated controlled environments — Part 8: Assessment of air cleanliness by chemical concentration (ACC)