Frequently Asked Question - Cleanroom Section

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      Comparison between selected equivalent classes of FS 209 and ISO 14644-1

ISO 14644-1 Classes	Class 3	Class 4	Class 5	Class 6	Class 7	Class 8
Federal Standard	Class 1	Class 10	Class 100	Class 1000	Class 10000	Class 100000

It should be appreciated that the airborne particle concentration of a given cleanroom is dependent on the particle generating activities going on in the room. 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 in it production equipment that is operating, there should be a greater particle concentration, but the greatest concentration occurs when the room is in full production. The 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 condition where the installation is functioning in the specified manner, with the specified number of personnel present and working in the manner agreed upon.

The ISO 14644-1 standard also gives a method by which the classification of a cleanroom is ascertained. The method is for determining the number of sampling locations, the sampling volume and counting the number of airborne particles.