Understanding ISO Standards for Cleanrooms

Although the revised ISO cleanroom standards have been in place for quite some time – well over 10 years, in fact – there remains the potential for confusion over terminology and nomenclature. In addition, it’s also important to keep in mind that, as with any specification or measurement, there are limitations with these standards.

As a quick refresher, what exactly are the ISO standards and what do they mean?  ISO 14644-1 classification of air cleanliness and ISO 14644-2 deal with particle size and particle count, Shoe Coverestablishing a cleanroom rating of ISO 1-9 based on those factors.  As you know, cleanroom users and engineers will typically refer to a room as an “ISO 4,” “ISO 5,” and so on. While lower numbered ISO specs require the full complement of coveralls, shoe covers, and similar garments, higher numbered rooms like an ISO 9 can be entered in garments like a frock covering everyday clothes.

On to the more important point: what are the limitations of these cleanroom measurements? They require less information about the cleanroom than Federal Standard 209 did, and allow for fewer tester locations for cleanliness.  The ISO standards establish 0.1 micron as the standard particle diameter, create three new cleanliness classes, and aren’t as concerned with airflow velocity, room pressure, room temperature, and the distance from the floor or the filter face when taking an air sample for a particle count. This variability can lead to fluctuations in particulate levels and thus, in ISO classifications.

Because of these limitations, it’s important to be aware of at what state testing was done: at rest, as built, or in operation, and to keep all factors in mind.  When you work with Liberty for your cleanroom needs, you can be sure you’re dealing with experts who know exactly what makes for the best possible cleanroom.  You can trust that we are aware of everything that’s crucial to the process, and know your cleanroom will be the best possible.

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