How are particle count measurements taken?

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Particle count measurements are typically performed on 10 mL of oil with results averaged to 1 mL. Prior to counting, particles in the sample must be homogenized which is done by shaking, sonication, de-gassing, etc. Consistency is key when preparing samples. When a sample is ready, it is loaded into a syringe and the sample passes through a laser sensor at a controlled flow rate to ‘count’ the number of particles at various size ranges during the test period.