Particle counting is a valuable part of any oil analysis program as the use of clean oil cannot be emphasized enough. This test employs a laser particle count instrument that counts the number of particles in a specific size range per a given volume of sample.
Particle count calibration techniques and reporting of results standards have been developed to assist in obtaining consistent results and meeting targeted cleanliness levels. ISO 11171 defines the proper techniques for instrument calibration while ISO 4406 simplifies reporting of particle count data by assigning cleanliness codes based on the total number of particles in three given size ranges – for example 22/20/16.
The first cleanliness code corresponds to the number of particles greater than 4um, the second cleanliness code corresponds to the number of particles greater than 6um, and the third to particles greater than 14um. Abnormal particle contamination levels are associated with increased wear, fluid contamination or degradation and loss of filter efficiency.