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ISO Cleanroom Classification
Cleanrooms are classified by cleanliness, measured by the number and size of particulates in the air. The International Standards Organization (ISO) has established a classification system specifically for cleanroom environments. The ISO 14644-1 cleanroom standards are composed of nine classifications for cleanrooms based on the maximum number and size of particulates that exist per cubic meter. A Class 1 designation indicates the highest level of cleanliness with the least number of particulates, while Class 9 indicates the lowest level of cleanliness with the maximum number of particles in the air. For more detailed information, see the chart below.
ISO 14644-1:2015 Cleanroom Standard – This chart details for each classification the maximum number of particles in micrometers (µm) permitted per cubic meter of air.
|Class||Maximum Particles per m3|
|≥0.1 μm||≥0.2 μm||≥0.3 μm||≥0.5 μm||≥1 μm||≥5 μm|
Different industries require different standards of cleanliness in their cleanrooms. We work with you to ensure your space meets the requirements for your specific application.
- Cleanrooms with this classification can have a maximum of 1,000 particles under size 0.1 µm present per cubic meter of air. ISO Class 3 cleanrooms allow up to eight particles 1 µm in size and do not allow any particles larger than 1 µm.
- Class 4 cleanrooms allow slightly more flexibility with up to 10,000 of the smallest measured particles present per cubic meter and additional particle counts of larger sizes. This classification does not allow any particles larger than 1 µm and allows a maximum of 83 particles of size 1 µm.
- These cleanrooms allow for bigger particles than Class 3 or Class 4 cleanrooms, with up to 832 particles that are less than 1 µm and up to 29 particles that are less than 5 µm. This classification also permits up to 100,000 particles less than 0.1 µm in size. Class 5 cleanrooms are often used for Grade A production, a classification frequently required by aseptic preparation and filling applications.
- Class 6 cleanrooms allow particles of all six size classifications, with up to 1,000,000 particles smaller than 0.1 µm allowed per cubic meter of air. These cleanrooms also allow a maximum of 293 particles at or under 5 µm.
- This classification no longer counts particles under 0.3 µm separately and allows up to 352,000 particles at or under 0.5 µm per cubic meter. Class 7 cleanrooms may also have up to 2,930 particles less than 5 µm. These cleanrooms are also classified as Grade C, which means that during operation, 3,500,000 particles smaller than 0.5 µm may be present at any given time. Class 7 cleanrooms are commonly used in pharmaceutical applications.
- ISO Class 8 cleanrooms are slightly cleaner than room air, with up to 3,520,000 particles less than 0.5 µm and up to 293,000 particles smaller than 5 µm allowed. This classification is also commonly associated with Grade D cleanrooms, which are typically used to carry out less critical stages in the manufacture of sterile products.
STERIS offers modular cleanrooms, cleanroom certification and biodecontamination services to help you achieve the cleanroom classification you require.