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ISO 14644 Cleanroom Classes Explained

What is ISO 14644?

ISO 14644-1 is the international standard that classifies the cleanliness of air in cleanrooms and controlled environments by the maximum allowed concentration of airborne particles. It replaced the older US Federal Standard 209E (Class 100, 1000, etc.).

The ISO classes

ISO 14644-1 defines classes from ISO 1 (cleanest) to ISO 9. In practice, most pharmaceutical, biotech and electronics work uses ISO Class 5 to ISO Class 8. ISO Class 5 allows a maximum of 3,520 particles ≥0.5µm per cubic metre — the level provided by a laminar flow hood or a Grade A zone.

How to choose your class

The required class depends on your process. Sterile compounding and aseptic filling typically need ISO 5 at the point of work; surrounding areas may be ISO 7 or 8. Our team helps you specify the right class for each zone. See our modular cleanrooms and laminar flow hoods.

Frequently Asked Questions

What is the cleanest ISO class?
ISO Class 1 is the cleanest under ISO 14644-1, but most real-world applications use ISO 5 to ISO 8.
Is ISO Class 5 the same as Class 100?
Yes — ISO Class 5 corresponds to the former US Federal Standard 209E "Class 100".

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