How are cleanrooms classified?
Before we discuss the different classes of cleanrooms, let’s talk about the meaning of the word “particle”. Airborne particles range in different sizes, and are measured in microns. For example, a human hair is 100 microns, and dust is equal to 25 microns. Cleanrooms are classified based on the number of particles that flow through the room. The classification is based upon particles .5 microns and larger per cubic foot of air. Table I illustrates the different classes of cleanrooms. The standard for cleanrooms does not correlate with standards for cleanroom apparel. Testing for apparel is conducted with a Helmke Drum Test. Table II illustrates the results of this test. Another standard that regulates manufacturers is ISO (International Standards Organization). The ISO 9000 series is a set of generic standards that provide quality management guidance and identify generic quality system elements necessary to achieve quality manufacturing.
