The Misapplication of "Composite Correlation of Cleanliness Levels"
COMPUTATIONAL SYSTEMS INC KNOXVILLE TN
Pagination or Media Count:
Contamination control for hydraulics and lubricants is a proactive approach to achieve extended machine life. Particle counting is a proven contamination monitoring method and is an essential part of contamination control. Many particle counting standards have been developed and are in widespread use. Some include ISO 4406 code, particles per ml 10 micron, gravimetric method mgL, MIL STD 1246a, NAS 1638 code, and SAE code Disavowed. The table, Composite Correlation of Cleanliness Levels, has been used in many referenced publications to show equivalent relationships between all of these standards. In its correct application, this table shows the equivalence between these standards when using air cleaner fine test dust ACFTD standard contaminant. A frequent misapplication of this chart is to assume incorrectly that it describes equivalence when testing used hydraulic and lubricant oil samples instead of ACFTD standard contaminant. This paper shows the extent to which particle count data collected from actual samples does not comply with this table. It shows how one can be led to incorrect condition monitoring analysis and wrong recommended actions by using this table to translate particles per ml 10 microns into ISO and NAS code levels. It shows the importance of actually counting particles at multiple sizes rather than assuming the size distribution of ACFTD standard contaminant.
- Lubricants and Hydraulic Fluids