Particle Count

ISO 11171: A count of the number of particles present greater than given micron sizes per unit volume of fluid. The results reflect the solid contaminants present and are applied to assess fluid cleanliness and filtration efficiency. Cleanliness levels are also represented by the ISO 4406 classification system to classify the particles larger than 4-μm, 6-μm, and 14-μm per milliliter of fluid (for example: 18/16/14).