The ISO 4406:1999 (International Standards Organization) cleanliness level standard has gained wide acceptance in most industries today. This standard references the number of particles greater than 4, 6, and 14 micrometers in a known volume, usually 1 milliliter or 100 milliliters. The number of 4+ and 6+ micrometer particles is used as a reference point for “silt” particles. The 14+ size range indicates the quantity of larger particles present which contribute greatly to possible catastrophic component failure. Please refer to the following explanation:
An ISO classification of 19/16/13 can be defined as following:
