BS ISO 11500:2008

1   Scope This International Standard specifies an automatic particle counting procedure for determining the number and sizes of particles present in hydraulic-fluid bottle samples of clear, homogeneous, single-phase liquids using an automatic particle counter (APC) that works on the light-extinction principle. This International Standard is applicable to the monitoring of

       a)  the cleanliness level of fluids circulating in hydraulic systems, 
   
   
     
       b)  the progress of a flushing operation, 
   
   
     
       c)  the cleanliness level of support equipment and test rigs, 
   
   
     
       d)  the cleanliness level of packaged stock. 
   
 


 
   NOTE 1  Measurements can be made with particles suspended in the original liquid or in a sample of the liquid diluted with a compatible liquid to reduce coincidence error. 


 
   NOTE 2  The presence of a fluid interface obstructs the light beam and gives false signals.