CYLINDER AS-HYDRAULIC 3621915 - Caterpillar

Table 1
Filter Efficiency % =     Number of Particles Captured     x 100    
Number of Particles Entering Note: Early plugging of a filter does not indicate a "bad quality" filter. Early plugging can indicate higher than usual debris in the fluid. Early plugging indicates that the filter is performing as designed and capturing contaminants. Early plugging may occur in early hours of operation. If early plugging occurs inspect the system for potential causes.
When installing a new fluid filter, never add the used fluid into the new filter to help the engine or the machine compartment start. The dirty fluid is added at the clean side of the filter and will contaminate the engine or machine compartment with dirty fluid. Follow all the instructions for filter installation that are printed on the filter can or as described in your Operation and Maintenance Manual.