What are the acceptable error ranges of repeatability?

According to ISO 13320: 2020, six consecutive measurements should be carried out to satisfy the repeatability test. The average values of D10, D50, and D90 should be calculated, and the acceptable error ranges are:

♦ D10

Each measured value of D10 should not be deviated from the average value by more than ±2%.

♦ D50

Each measured value of D50 should not be deviated from the average value by more than ±1.5%.

♦ D90

Each measured value of D90 should not be deviated from the average value by more than ±3%.

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