What is the primary purpose of sub-dividing powder samples?

To obtain a small, manageable test aliquot that accurately represents the true particle size distribution of the entire bulk gross sample without segregation.

How wide should the chutes be on a sample splitter?

The chute width should be at least three times the maximum particle size of the powder to prevent blockage and bridging.

Which sub-division method is considered the most accurate?

A rotary sample divider (spinning riffler) generally provides the most statistically representative sub-samples by taking many small increments over time.

IS 4879

: 1968

Method of sub-division of a gross sample of powder used for determination of particle size

CurrentSpecializedTesting MethodMaterials Science · Sieves, Sieving and Other Sizing Methods

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This standard provides uniform procedures for accurately sub-dividing a gross bulk sample of powder into smaller, representative test portions for particle size determination, minimizing size segregation and operator bias.

Method of sub-division of a gross sample of powder used for determination of particle size

Quick Reference Values

Minimum chute width for riffler3 times the maximum particle size

Moisture condition of sampleCompletely dry to prevent agglomeration

Recommended subdivision method for highest accuracyRotary sample division

Practical Notes

Always ensure the powder is thoroughly mixed and completely dry before sub-division to prevent agglomeration and unequal splitting.

When using a chute riffler, feed the powder evenly along the entire length to prevent size segregation bias.

Coning and quartering is highly dependent on operator skill; mechanical dividers like spinning rifflers are preferred for higher precision.