Summary of FS 209E and ISO 14644-1 and ISO 14644-2

The cleanliness classification levels defined by FS209E and ISO 14644-1 are approximately equal, except the new ISO standard uses new class designations, a metric measure of air volume and adds three additional classes - two cleaner than Class 10 and one beyond than Class 100,000. The second new ISO standard, ISO 14644-2, gives requirements for monitoring a clean-room or clean zone to provide evidence of its continued compliance with ISO 14644-1.

The following table compares FED STD 209E to the new ISO 14644-1 classifications.

The ISO standard also requires fewer sample locations, especially as the clean-room/area size increases; however, the ISO standard does require minimum one minute samples, whereas the Federal Standard allows shorter samples, especially at smaller particle sizes.

For example, to certify an FS Class 10 clean-room (ISO class 4), with 250 square feet (7.08 square meters), classified at 0.3 micron with a 1 cf/m flow rate particle counter, the required number of sample locations, sample volumes, and sample times would be as follows:

FS209E requires 10 sample locations, 19.6 liter minimum sample volume (0.85 cf), and a sample time of 51 seconds. This yields a total minimum sample time of 510 seconds and 10 equipment moves.

ISO 14644-1 requires 3 sample locations, 19.6 liter minimum sample volume (0.85 cf ), but also a minimum sample time of one minute yielding three samples of one cubic foot. This yields a total sample time of 180 seconds and three equipment moves.

The precise count levels required by ISO 14644-1 for each classification, by particle size, are given below.

ISO 14644-2 determines the type and frequency of testing required to conform with the standard. The following tables indicate which tests are mandatory and which tests are optional.