Specifications

67
Guide to Contamination Standards
This guidebook is aimed at engineers, technicians and quality control personnel involved
in contamination control. Its purpose is to make available accepted and widely-used
cleanliness speci cation levels for liquid samples.
The tables in this guide allow users of using automatic portable particle counters to see the
relationship between raw particle counts at various sizes and the reporting code numbers of
various contamination standards.
A NOTE ON THE FIGURES USED
Note that some of the table entries are de ned as cumulative counts (e.g. “> 6µm”) and
others are de ned as differential counts (e.g. 6–14µm”).
Instances of particle sizes given as “µm” refer to ACFTD (i.e. Air Cleaner Fine Test Dust)
distributions. Instances of particle sizes given as “µm(c)” refer to MTD (i.e. ISO Medium Test
Dust) distributions.
All standards are in counts per volume, and provide easy methods for converting particle
counts into limits that are simple to interpret. By noting the requirements of the standard,
particle counts can be accurately converted to contamination levels.