201.028 REV 1 Date of Issue: 18 June 2018
Furthermore, without the benefits of significant research material and the existence of standard contaminant
sensitivity tests, manufacturers who publish recommendations that are cleaner than competitors may be viewed
as having a more sensitive product.
Hence there may be a possible source of conflicting information when comparing cleanliness levels recommended
from different sources.
The table gives a selection of maximum contamination levels that are typically issued by component
manufacturers. These relate to the use of the correct viscosity mineral fluid. An even cleaner level may be needed
if the operation is severe, such as high frequency fluctuations in loading, high temperature or high failure risk.
11.8 Hydraulic System Target Cleanliness Levels
Where a hydraulic system user has been able to check cleanliness levels over a considerable period, the
acceptability, or otherwise, of those levels can be verified.
Thus if no failures have occurred, the average level measured may well be one which could be made a bench
mark. However, such a level may have to be modified if the conditions change, or if specific contaminant-sensitive
components are added to the system. The demand for greater reliability may also necessitate an improved
cleanliness level.
The level of acceptability depends on three features:
• The contamination sensitivity of the components
• The operational conditions of the system
• The required reliability and life expectancy
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