Impact of Test Dust Changes on Particle Size, Particle Count, and Fluid Cleanliness Classes

摘要

For several decades, AC Fine Test Dust (ACFTD) has been utilized for a number of purposes in the area of hydraulic and lubrication contamination control. It was used for primary calibration of automatic optical particle counters, utilized in laboratories to measure the particle size distribution of a fluid sample, either on-line or collected from the operating system in a sample bottle. ACFTD is no longer being produced and many standards organizations are now selecting replacement dusts, most notably ISO 12103-A3, for calibration and testing purposes. Because none of the replacement dusts has identical particle size distribution characteristics to ACFTD, all associated test results are somewhat different. This paper presents typical changes found with the new dusts including the impact on automatic particle counter calibration, resultant particle sizes, particle counts, and fluid cleanliness classes and codes defined in fluid cleanliness standards commonly used in the industry. It should be pointed out that, although the particle sizes defined by the new calibration, and hence, fluid cleanliness codes or classes, will be changing, this is an artifact of the measurement, and actual contamination levels in the field will remain the same as before.