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Cleanroom ISO Standards

Selected ISO 14644-1 airborne particulate cleanliness classes for cleanrooms and clean zones

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ISO Classification Number Maximum concentration limited (particles/m3 of air) for particles equal to and larger than the considered sizes shown below
  ≥0.1µm ≥0.2µm ≥0.3µm ≥0.5µm ≥1µm ≥5.0µm
ISO Class 1 10 2        
ISO Class 2 100 24 10 4    
ISO Class 3 1 000 237 102 35 8  
ISO Class 4 10 000 2 370 1  020 352 83  
ISO Class 5 100 000 23 700 10 200 3 520 832 29
ISO Class 6 1 000 000 237 000 102 000 35 200 8 320 293
ISO Class 7       352 000 83 200 2 930
ISO Class 8       3 520 000 832 000 29 300
ISO Class 9       35 200 000 8 320 000 293 000
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Comparison between selected equivalent classes of FS 209 and ISO 14644-1

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ISO 14644 Classes Class 3 Class 4 Class 5 Class 6 Class 7 Class 8
FS 209 Classes Class 1 Class 10 Class 100 Class 1 000 Class 10 000 Class 6 100 000
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If a room is empty, a very low particle concentration can be achieved, this closely reflecting the quality of air supplied.  If the room has production equipment in it that is operating, these should be greater particle concentration, but the greatest concentration occurs when the room is in full production.  This classification of the room may therefore be carried out in these different occupancy states.

The occupancy states defined in ISO 14644-1 are as follows:

As built: the condition where the installation is complete with all services connected and functioning, but with no production equipment, materials or personnel present.

At-rest: The condition where the installation is complete with equipment installed and operating in a manner agreed between the customer and supplier, but with no personnel present.

Operational: The conditional where the installation is functioning in the specified manner, with the specified number of personnel present and working in the manner agreed upon.