Application

This guide describes standardized procedures for determination of the concentration of airborne particles in the ultrafine size range (i.e., particles with a size distribution having a threshold [lower limit] particle size smaller than 0.1 µm). The numerical value of the concentration of such particles, expressed in terms of particles per cubic meter, is the U descriptor. This term may refer to a specified concentration of ultrafine particles or to measurement of the concentration of ultrafine particles in a given sample of air.

The procedures described herein are suitable for use in conjunction with related cleanroom standards, such as ISO 14644-1 for determination of airborne particulate cleanliness, and ISO 14644-2 for monitoring. The procedures are applicable to cleanrooms and clean zones in any of three occupancy states, as defined in ISO 14644-1.

This document is most appropriate for use with cleanroom and clean zone environments that qualify as ISO Class 4 or cleaner, as defined in ISO 14644-1.