OIL ANALYSIS TESTS

NAS 1638 Particle Count

The sample is pumped through a sensor, which counts and sizes the particles. A 100ml of sample is counted and the particles are grouped into various size ranges. The results are assessed against NAS 1638 to give ratings which determine the cleanliness of the fluid.

Hydraulic systems are sensitive to the presence of solid particulate matter or 'dirt'. Dirt particles interact with moving surfaces that accelerate wear. If they are not removed or at least diluted, loss of operating efficiency and eventual breakdown is more likely. Sizing and counting of particulate contamination in hydraulic fluids are measured by a Particle Size Analyzer. Counts are recorded as particles per 100 ml in the ranges 5-15, 15-25, 25-50, 50-100, 100+ microns. Limits are set by the manufacturers.

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